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297 tm march 1997 82c85 cmos static clock controller/generator features ? generates the system clock for cmos or nmos microprocessors and peripherals ? complete control over system operation for very low system power - stop-oscillator - low frequency - stop-clock - full speed operation ? dc to 25mhz operation (dc to 8mhz system clock) ? generates 50% and 33% duty cycle clocks (synchronized) ? uses a parallel mode crystal circuit or external frequency source ? ttl compatible inputs/outputs ? 24 lead slimline dual-in-line or 28 pad square lcc package options ? single 5v power supply ? operating temperature range - c82c85 . . . . . . . . . . . . . . . . . . . . . . . . . . 0 o c to +70 o c - i82c85 . . . . . . . . . . . . . . . . . . . . . . . . . -40 o c to +85 o c - m82c85 . . . . . . . . . . . . . . . . . . . . . . . -55 o c to +125 o c pinouts 24 lead cerdip top view description the intersil 82c85 static cmos clock controller/genera- tor provides complete control of static cmos system oper- ating modes and supports full speed, slow, stop-clock and stop-oscillator operation. while directly compatible with the intersil 80c86 and 80c88 16-bit static cmos microproces- sor family, the 82c85 can also be used for general system clock control. for static system designs, separate signals are provided on the 82c85 for stop (s0, s1, s2/stop ) and start (start) control of the crystal oscillator and system clocks. a single control line (slo /fst) determines 82c85 fast (crystal/efi frequency divided by 3) or slow (crystal/efi frequency divided by 768) mode operation. automatic maximum mode 80c86 and 80c88 software halt instruction decode logic in the 82c85 enables software- based clock control. restart logic insures valid clock start- up and complete synchronization of system clocks. the 82c85 is manufactured using the intersil advanced scaled saji iv cmos process. in addition to clock control circuitry, the 82c85 also contains a crystal controlled oscillator (up to 25mhz), clock generation logic, complete ?ready? synchronization and reset logic. this permits the designer to tailor the system power-performance product to provide optimum performance at low power levels. 28 lead plcc, clcc top view ordering information part number package temp. range pkg. no. cs82c85 28 ld plcc 0 o c to +70 o cn28.45 is82c85 -40 o c to +85 o cn28.45 cd82c85 24 ld cerdip 0 o c to +70 o c f24.3 id82c85 -40 o c to +85 o c f24.3 md82c85/b -55 o c to +125 o c f24.3 mr82c85/b 28 pad clcc -55 o c to +125 o cj28.a csync pclk aen1 rdy1 ready rdy2 aen2 clk gnd clk50 start slo /fst v cc x2 async efi f/c res s2 /stop s1 s0 x1 osc reset 1 2 3 4 5 6 7 8 9 10 11 12 16 17 18 19 20 21 22 23 24 15 14 13 23 24 25 22 21 19 11 3 2 1 4 14 15 16 17 18 12 13 28 27 26 10 5 6 7 8 9 rdy1 ready rdy2 aen2 clk gnd nc nc async efi f/c osc res reset clk50 start slo /fst nc s0 s2 /stop s1 aen1 pclk csync nc v cc x2 x1 20 fn2976.1 caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. 1-888-intersil or 321-724-7143 | intersil (and design) is a trademark of intersil americas inc. copyright ? intersil americas inc. 2002. all rights reserved
298 pin descriptions symbol dip pin number type description x1 x2 23 22 i o crystal connections: x1 and x2 are the crystal oscillator connections. the crystal frequency must be 3 times the maximum desired processor clock frequency. x1 is the oscillator circuit input and x2 is the output of the oscillator circuit. if the crystal inputs are not used, x1 must be tied to v cc or gnd, and x2 should be left open. efi 20 i external frequency in: when f/c is high, clk is generated from the efi input signal. this input signal should be a square wave with a frequency of three times the maximum desired clk output frequency. if the crystal inputs are not used. xi must be tied to v cc or gnd, and x2 should be left open. f/c 19 i frequency/crystal select: f/c selects either the crystal oscillator or the efi input as the main frequency source. when f/c is low, the 82c85 clocks are derived from the crystal oscillator circuit. when f/c is high, clk is generated from the efi input. f/c cannot be dynamically switched during normal operation. start 11 i a low-to-high transition on start will restart the clk, clk50 and pclk outputs after the appro- priate restart sequence is completed. when in the crystal mode (f/c low) with the oscillator stopped. the oscillator will be restarted when a start command is received. the clk, clk50 and pclk outputs will start after the oscillator input signal (x1) reaches the schmitt trigger input threshold and 8k internal counter reaches termi- nal count. if f/c is high (efi mode), clk, clk50 and pclk will restart within 3 efi cycles after start is recognized. the 82c85 will restart in the same mode (slo /fst) in which it stopped. a high level on start disables the stop mode. so s1 s2 /stop 13 14 15 i i i s2 /stop , s1, so are used to stop the 82c85 clock outputs (clk, clk50, pclk) and are sampled by the rising edge of clk, clk50 and pclk are stopped by s2 /stop , s1, so being in the lhh state on the low-to-high transition of clk. this lhh state must follow a passive hhh state occurring on the previous low-to-high clk transition. clk and clk50 stop in the high state when f/c is low and may stop in either the high or low state when f/c is high. pclk stops in its current state (high or low). when in the crystal mode (f/c ) low and a stop command is issued, the 82c85 oscillator will stop along with the clk, clk50 and pclk outputs. when in the efi mode, only the clk, clk50 and pclk out- puts will be halted. the oscillator circuit if operational, will continue to run. the oscillator and/or clock is restarted by the start input signal going true (high) or the reset input (res ) going low. slo /fst 12 i slo /fst is a level-triggered input. when high, the clk and clk50 outputs run at the maximum frequency (crystal or efi frequency divided by 3). when low, clk and clk50 frequencies are equal to the crystal or efi frequency divided by 768. slo /fst changes are internally synchronized so proper clk and clk50 phase relationships are maintained and minimum pulse width specifica- tions are met. start and stop control of the oscillator or efi is available in either the slow or fast frequency modes. the slo /fst input must be held low for at least 195 osc/efi clock cy- cles before it will be recognized. this eliminates unwanted frequency changes which could be caused by glitches or noise transients. the slo /fst input must be held high for at least 6 osc/efi clock pulses to guarantee a transition to fast mode operation. clk 8 o processor clock: clk is the clock output used by the 80c86 or 80c88 processor and other peripheral devices. when slo /fst is high, clk has an output frequency which is equal to the crys- tal or efi input frequency divided by three. when slo /fst is low, clk has an output frequency which is equal to the crystal or efi input frequency divided by 768. clk has a 33% duty cycle. clk50 10 o 50% duty cycle clock: clk50 is an auxiliary clock with a 50% duty cycle and is synchronized to the falling edge of clk. when slo /fst is high, clk50 has an output frequency which is equal to the crystal or efi input frequency divided by 3. when slo /fst is low, clk50 has an output fre- quency equal to the crystal or efi input frequency divided by 768. pclk 2 o peripheral clock: pclk is a peripheral clock signal whose output frequency is equal to the crystal or efi input frequency divided by 6 and has a 50% duty cycle. pclk frequency is unaffected by the state of the slo /fst input. osc 18 o oscillator output: osc is the output of the internal oscillator circuitry. its frequency is equal to that of the crystal oscillator circuit. osc is unaffected by the state of the slo /fst input. when the 82c85 is in the crystal mode (f/c low) and a stop command is issued, the osc output will stop in the high state. when the 82c85 is in the efi mode (f/c high, the oscillator (if operational) will continue to run when a stop command is issued and osc remains active. 82c85
299 functional block diagram res 17 i reset in: res is an active low signal which is used to generate reset. the 82c85 provides a schmitt trigger input so that an rc connection can be used to establish the power-up reset of proper duration. res starts crystal oscillator operation. reset 16 o reset: reset is an active high signal which is used to reset the 80c86 family processors. its timing characteristics are determined by res . reset is guaranteed to be high for a minimum of 16 clk pulses after the rising edge of res . csync 1 i clock synchronization: csync is an active high signal which allows multiple 82c85 and 82c84a to be synchronized to provide multiple in-phase clock signals when csync is high, the internal counters are reset and force clk, clk50 and pclk into a high state. when csync is low, the internal counters are allowed to count and the clk, clk50 and pclk outputs are active. csync must be externally synchronized to efi. aen1 aen2 3 7 i i address enable: aen is an active low signal. aen serves to qualify its respective bus ready signal (rdy1 or rdy2). aen1 validates rdy1 while aen2 validates rdy2. two aen signal inputs are useful in system configurations which permit the processor to access two multi-master system buses. rdy1 rdy2 4 6 i i bus ready: (transfer complete). rdy is an active high signal which is an indication from a de- vice located on the system data bus that data has been received, or is available rdy1 is qualified by aen1 while rdy2 is qualified by aen2 . async 21 i ready synchronization select: async is an input which defines the synchronization mode of the ready logic. when async is low, two stages of ready synchronization are pro- vided. when async is left open or high a single stage of ready synchronization is provided. ready 5 o ready: ready is an active high signal which is the synchronized rdy signal input. gnd 9 i ground v cc 24 i v cc : is the +5v power supply pin. a 0.1mf capacitor between v cc and gnd is recommended. pin descriptions (continued) symbol dip pin number type description stop logic sync logic peripheral clock (divide by 6) ready sync oscillator ready select speed select div 256 or div 1 restart logic clock (divide logic by 3) reset pulse conditioning logic reset clk clk50 pclk osc ready (16) (8) (10) (2) (18) (5) (17) (1) (12) (19) (23) (21) (11) (20) (22) (15) (14) (13) (4) (3) (7) (6) res start csync slo /fst f/c efi x2 x1 s2 /stop s1 s0 rdy1 aen1 aen2 rdy2 async restart sync master selected osc halt v cc (24) gnd (9) osc osc external freq. select 82c85
300 functional description the 82c85 static clock controller/generator provides sim- ple and complete control static cmos system operating modes. the 82c85 supports full speed, slow, stop-clock and stop-oscillator operation. while it is directly compatible with the intersil 80c86 and 80c88 cmos 16-bit static micropro- cessors, the 82c85 can also be used for general purpose system clock control. the 82c85 pinout is a superset of the 82c84a clock gener- ator/driver. 82c85 pins 1-9, 16-24 are compatible with 82c84a pins 1-9, 10-18 respectively. an 82c84a can be placed in the upper 18 pins of an 82c85 socket and it will operate correctly (without the ability to control the clock and oscillator operation.) this allows dual design for simple sys- tem upgrades. the 82c85 will also emulate an 82c84a when pins 11-15 on the 82c85 are tied to v cc . for static systems designs, separate signals are provided on the 82c85 for stop and start control of the crystal oscillator and clock outputs. a single control line determines 82c85 fast (crystal/efi frequency divided by 3) or slow (crystal/efi frequency divided by 768) mode operation. the 82c85 also contains a crystal controlled oscillator, clock generation logic, complete ?ready? synchronization and reset logic. automatic 80c86/88 software halt instruction decode logic is present to ease the design of software-based clock control systems and provide complete software control of stop mode operation. restart logic insures valid clock start-up and complete synchronization of clk, clk50 and pclk. static operating modes in static cmos system design, there are four basic operat- ing modes. the 82c85 static clock controller supports each of them. these modes are: fast, slow, stop-clock and stop-oscillator. each has distinct power and per- formance characteristics which can be matched to the needs of a particular system at a specific time (see table 1). keep in mind that a single system may require all of these operating modes at one time or another during normal opera- tion. a design need not be limited to a single operating mode or a specific combination of modes. the appropriate operating mode can be matched to the power-performance level needed at a specific time or in a particular circumstance. reset logic the 82c85 reset logic provides a schmitt trigger input (res ) and a synchronizing flip-flop to generate the reset timing. the reset signal is synchronized to the falling edge of clk. a simple rc network can be used to provide power-on reset by utilizing this function of the 82c85. when in the crystal oscillator (f/c = low) or the efi (f/c = high) mode, a low state on the res input will set the reset output to the high state. it will also restart the oscil- lator circuit if it is in the idle state. the reset output is guar- anteed to stay in the high state for a minimum of 16 clk cycles after a low-to-high transition of the res input. an oscillator restart count sequence will not be disturbed by reset if this count is already in progress. after the restart counter expires, the reset output will stay high at least for 16 periods of clk before going low. reset can be kept high beyond this time by a continuing low input on the res input. if f/c is low (crystal oscillator mode), a low state on res starts the crystal oscillator circuit. the stopped outputs remain inactive, until the oscillator signal amplitude reaches the x1 schmitt trigger input threshold voltage and 8192 cycles of the crystal oscillator output are counted by an inter- nal counter. after this count is complete, the stopped outputs (clk, clk50, pclk, and osc) start cleanly with the proper phase relationships. this 8192 count requirement insures that the clk, clk50 and pclk outputs will meet minimum clock requirements and will not be affected by unstable oscillator characteristics which may exist during the oscillator start-up sequence. this sequence is also followed when a start command is issued while the 82c85 oscillator is stopped. oscillator/clock start control once the oscillator is stopped (or committed to stop) or at power- on, the restart sequence is initiated by a high state on start or low state on res . if f/c is high, then restart occurs imme- diately after the start or res input is synchronized internally. this insures that stopped outputs (clk, pclk, osc and clk50) start cleanly with the proper phase relationship. if f/c is low (crystal oscillator mode), a high state on the start input or a low state on res causes the crystal oscil- lator to be restarted. the stopped outputs remain stopped, table 1. static system operating mode characteristics operating mode description power level performance stop-oscillator all system clocks and main clock oscillator are stopped maximum savings slowest response due to oscillator restart time stop-clock system cpu and peripherals clocks stop but main clock oscillator continues to run at rated frequency reduced system power fast restart-no oscillator restart time slow system cpu clocks are slowed while peripheral clock and main clock oscillator run at rated frequency power dissipation slightly higher than stop-clock continuous operation at low frequency fast all clocks and oscillators run at rated frequency highest power fastest response 82c85
301 until the oscillator signal amplitude reaches the x1 schmitt trigger input threshold voltage and 8192 cycles of the crystal oscillator output are counted by an internal counter. after this count is complete, the stopped outputs (clk, clk50, pclk, and osc) start cleanly with the proper phase rela- tionships. typically, any input signal which meets the start input tim- ing requirements can be used to start the 82c85. in many cases, this would be the int output from an 82c59a cmos priority interrupt controller (see figure 1). this output, which is active high, can be connected to both the 82c85 start pin and to the appropriate interrupt request input on the microprocessor. when the int output becomes active, the oscillator/clock cir- cuit on the 82c85 will restart. upon completion of the appro- priate restart sequence, the clk signal to the cpu will become active. the cpu can then respond to the still pend- ing interrupt request. if the 82c59a/82c85 restart combination is used in conjunc- tion with an 82c55a stop control, the 82c55a must be ini- tialized prior to the 82c59a after reset. the 82c59a interrupt output is driven high at reset, causing the 82c85 to remain in the start mode regardless of the state of the s2 /stop input. this will avoid stopping the 82c85 due to negative transitions on the s2 /stop input which may occur during a mode change on the 82c55a or during the opera- tion of any peripheral i/o device prior to initialization. another method of insuring proper operation of the start function upon reset or system initialization is to bias the s2 /stop input low with an external pull-down resistor. the s2 /stop input will remain low until driven high by the 82c55a port pin or by external logic. this insures that the 82c85 stop command (hhh prior to lhh requirement on the status inputs) will not be satisfied. to minimize power dissipation in this case (using a pulldown resistor), the s2 /stop input should be normally low and pulsed high to develop the necessary hhh-to-lhh stop sequence. in this manner, the output driving the s2 /stop input will be normally low and will not be driving to the opposite state of the pull-down resistor. fast mode the most common operating mode for a system is the fast mode. in this mode, the 82c85 operates at the maximum fre- quency determined by the main oscillator or efi frequency. 82c59a 82c85 start clk s0 s1 s2 /stop slo /fst 80c86/88 intr clk pa0 pa1 82c55a int v cc figure 1. cmos peripheral control of 82c85 stop, start and slow/fast operations table 2. typical system power supply current for static cmos operating modes fast slow stop-clock stop-osc cpu frequency 5mhz 20 khz dc dc xtal frequency 15mhz 15mhz 15mhz dc icc 82c85 24.7ma 16.9ma 14.1ma 24.4ma 80c88 23.8ma 173.0ma 106.6ma 106.6ma 82c82 1.7ma 6.5ma 1.0ma 1.0ma 82c86 1.4ma 14.0ma 1.0ma 1.0ma 82c88 3.5ma 14.3ma 3.8ma 3.8ma 82c52 151.2ma 72.0ma 1.0ma 1.0ma 82c54 943.0ma 915.0ma 3.5ma 1.0ma 82c55a 3.2ma 1.2ma 1.0ma 1.0ma 82c59a 580.0ma 520.0ma 1.0ma 1.0ma 74hcxx + other 2.9ma 10.0ma 90.0ma 90.0ma hm-6516 820.0ma 32.0ma 1.9ma 1.9ma hm-6616 6.3ma 52.5ma 12.0ma 12.0ma total 66.8ma 18.9ma 14.3ma 244.7ma all measurements taken at room temperature, v cc = +5.0v. power supply current levels will be dependent upon system configuration and frequency of operation. 82c85
302 fast mode operation is enabled by each of two conditions: ? the slo /fst input is high and a start or reset command is issued ? the slo /fst input is held high for at least 6 oscillator or efi cycles. alternate operating modes using alternate modes of operation (slow, stop-clock, stop- oscillator) will reduce the average system operating power dissipation in a static cmos system (see table 2). this does not mean that system speed or throughput must be reduced. when used appropriately, the slow, stopclock, stop-oscillator modes can make your design more power efficient while maintaining maximum system performance. stop-oscillator mode when the 82c85 is stopped while in the crystal mode (f/c low), the oscillator, in addition to all system clock signals (clk, clk50 and pclk), are stopped. clk and clk50 stop in the high state. pclk stops in it?s current state (high or low). with the oscillator stopped, 82c85 power drops to it?s lowest level. all clocks and oscillators are stopped. all devices in the system which are driven by the 82c85 go into the lowest power standby mode. the 82c85 also goes into standby and requires a power supply current of less than 100 a. stop-clock mode when the 82c85 is in the efi mode (f/c high) and a stop command is issued, all system clock signals (clk, clk50, and pclk) are stopped. clk and clk50 stop in the high state when f/c is low and may stop in either the high or low state when f/c is high. pclk stops in its current state (high or low). the 82c85 can also provide it?s own efi source simply by connecting the osc output to the efi input and pu lling the f/c input high. this puts the 82c85 into the external fre- quency mode using it?s own oscillator as an external source signal (see figure 2). in this configuration, when the 82c85 is stopped in the efi mode, the oscillator continues to run. only the clocks to the cpu and peripherals (clk, clk50 and pclk) are stopped. oscillator/clock stop operation three control lines determine when the 82c85 clock outputs or oscillator will stop. these are s0, s1 and s2 /stop . these three lines are designed to connect directly to the maximum mode 80c86 and 80c88 status lines or to be driven by external i/o signals (such as an 82c55a output port). in the maximum mode configuration, the 82c85 will auto- matically recognize a software halt command from the 80c86 or 80c88 and stop the system clocks or oscillator. this allows complete software control of the stop function. if the 80c86 or 80c88 is used in the minimum mode, the 82c85 can be controlled using the s2 /stop input (with s0 and s1 held high). this can be done using an external i/o control line, such as from an 82c55a or by decoding the state of the 80c86 minimum mode status signals. 82c85 status inputs s2 /stop , s1, s0 are sampled on the rising edge of clk. the oscillator (f/c low only) and clock outputs are stopped by s2 /stop , s1, s0 being in the lhh state on a low-to-high transition of clk. this lhh state must follow a passive hhh state occurring on the previous low-to- high clk transition. clk and clk50 will stop in the logic high state after two additional complete cycles of clk. pclk stops in it?s current state (high or low). this is true for both slow and fast mode operation. 80c86/88 maximum mode clock control the 82c85 stop function has been optimized for 80c86/88 maximum mode operation. in this mode, the three 82c85 sta- tus inputs (s2 /stop , s1, s0) are connected directly to the maximum mode status lines (s2, s1, s0) of the intersil 80c86 or 80c88 static cmos microprocessors (see figure 3). when in the maximum mode, the 80c86/88 status lines identify which type of bus cycle the cpu is starting to exe- cute. 82c85 s2 /stop , s1 and s0 control input logic will rec- ognize a valid maximum mode software halt executed by the 80c86 or 80c88. once this state has been recognized, the 82c85 stops the clock (f/c high) and oscillator (f/c low) operation. figure 2. stop-clock mode using 82c85 in efi mode with oscillator as frequency source x1 x2 efi f/c s2 /stop s1 s0 start osc v cc stop control start control mn/mx s0 s1 s2 s0 s1 s2 /stop 82c85 80c86/88 figure 3. 82c85 stop control using 80c86/88 maximum mode status lines 82c85
303 the 82c85 s2 /stop , s1 and s0 control lines were designed to detect a passive 111 state followed by a halt 011 logic state before recognizing the halt instruction and stopping the system clocks. in the maximum mode, the 80c86/88 status lines go into a passive (no bus cycle) logic 111 state prior to executing a halt instruction. the qualifi- cation of a passive no bus cycle logic 111 state insures that random transitions of the status lines into a logic 011 state will not stop the system clock. this is necessary since the status lines of the 80c86/88 transition through an unknown state during t3 of the bus cycle. once the halt instruction is decoded by the 82c85, either the oscillator is stopped (stop-oscillator mode f/c tied low) or the external frequency source is gated off inter- nally (stop-clock mode f/c high). when the halt instruction is decoded with f/c low, the clk and clk50 will be stopped in a logic high state after 2 additional cycles of the clock. pclk stops in it?s current state (high or low). this is true for both slow and fast mode operation. the halt instruction is detected in the same manner whether the 82c85 is in the slow or fast mode. independent stop control for minimum mode operation when the 80c86 and 80c88 microprocessors are config- ured in minimum mode (mn/mx pin tied high), their status lines s0, s1, and s2 assume alternate functions. the logic states and sequences (passive before a halt) necessary for automatic halt detect in the 82c85 do not occur as in the maximum mode. the 82c85 controller cannot use the microprocessor status lines to detect a software halt instruc- tion when operating in minimum mode. however, the negative edge-activated s2 /stop pin pro- vides a simple means for clock control in minimum mode 80c86 and 80c88 systems. s2 /stop can be used as an independent stop control when s1 and s0 are held in the logical high state. keeping the s0 and s1 inputs at a logic 1 level and transitioning s2 /stop from high to low will meet the passive 111 state prior to a 011 state requirement of the 82c85. this feature allows 82c85 operation with the 80c86 and 80c88 in the minimum mode, provides compatibility with other static cmos microprocessors and allows maxi- mum flexibility in a system. with s2/stop being used as a stand-alone stop com- mand line, system clocks can be controlled via an 82c55a programmable peripheral interface or other similar interface circuits. this is accomplished by driving the s2 /stop input with a port pin on the 82c55a (see figure 1). the 82c55a port pin should be configured as an output and must present a logic high to the s2 /stop input for at least one clk cycle, followed by a low state. this will meet the 82c85 status input requirement of 111 followed by a 011. when a logic 0 is written to a 82c55a port pin, the s2 / stop pin is pulled low, stopping the system clocks (clk, clk50, pclk). in essence, the 82c85 is software controlled via the 82c55a. as with the slo /fst interface, port c is a logical choice for this job since the individual bit set and reset com- mands available for this port make control of the s2 /stop input simple. a start command issued to the 82c85 will override a stop command and the 82c85 will begin normal operation. the low state of the negative-edge triggered s2 /stop input will not prohibit the clocks from restarting. after a start or res command, the 82c85 must see a passive (111) state followed by a halt (011) state to stop the system clocks. to accomplish this, the 82c55a port output must be brought high and then returned low again for the 82c85 to recognize the next stop command. external decode adds halt control ss0, io/m and dt/r can identify a minimum mode 80c88 halt execution. during t2 of the system timing (while ale is high), ss0, io/m , and dt/r go into a 111 state when the 80c88 is executing a software halt. these signals cannot be tied directly to the s2 /stop , s1 and s0 inputs since they are not guaranteed to go into a passive state prior to their 111 state. these signals can be decoded during the time ale is high to indicate a software halt execution. slow mode when continuous operation is critical but power consump- tion remains a concern, the 82c85 slow mode operation provides a lower frequency at the clk and clk50 outputs (crystal/efi frequency divided by 768). the frequency of pclk is unaffected. the slow mode allows the cpu and the system to operate at a reduced rate which, in turn, reduces system power. for example, the operating power for the 80c86 or 80c88 cpu is 10ma/mhz of clock frequency. when the slow mode is used in a typical 5mhz system, clk and clk50 run at approximately 20khz. at this reduced frequency, the aver- age operating current of the cpu drops to 200 a. adding the 80c86/88 500 a standby current brings the total current to 700 a. while the cpu and peripherals run slower and the 82c85 clk and clk50 outputs switch at a reduced frequency, the main 82c85 oscillator is still running at the maximum fre- quency (determined by the crystal or efi input frequency.) since cmos power is directly related to operating fre- quency, 82c85 power supply current will typically be reduced by 15-20%. clock slow/fast operation the slo /fst input determines whether the clk and clk50 outputs run at full speed (crystal or efi frequency divided by 3) or at slow speed (crystal or efi frequency divided by 768) (see figure 4). when in the slow mode, 82c85 stop-clock and stop-oscillator functions operate in the same manner as in the fast mode. internal logic requires that the slo /fst pin be held low for at least 195 oscillator or efi clock pulses before the slow mode command is recognized. this requirement eliminates unwanted fast-to-slow mode frequency changes which could be caused by glitches or noise spikes. to guarantee fast mode recognition, the slo/fst pin must be held high for at least 6 osc or efi pulses. the 82c85 will begin fast m ode operation on the next pclk 82c85
304 edge after fast command recognition. proper clk and clk 50 phase relationships are maintained and minimum pulse width specifications are met. fast-to-slow or slow-to-fast mode changes will occur on the next rising or falling edge of pclk. it is important to remember that the transition time for operating frequency changes, which are dependent upon pclk, will vary with the 82c85 oscillator or efi frequency. slow mode control the 82c55a programmable peripheral interface can be used to provide control of the slo /fst pin by connecting a port pin of the 82c55a directly to the slo /fst pin (see fig- ure 1). with the port pin configured as an output, software control of the slo /fst pin is provided by simply writing a logical one (fast mode) or logical zero (slow mode) to the corresponding port. port c is well-suited for this func- tion due to it?s bit set and reset capabilities. since pclk con- tinues to run at a frequency equal to the oscillator or efi frequency divided by 6, it can be used by other devices in the system which need a fixed high frequency clock. for example, pclk could be used to clock an 82c54 program- mable interval timer to produce a real-time clock for the sys- tem or as a baud rate generator to maintain serial data communications during slow mode operation. oscillator the oscillator circuit of the 82c85 is designed primarily for use with an external parallel resonant, fundamental mode crystal from which the basic operating frequency is derived. the crystal frequency should be selected at three times the required cpu clock. x1 and x2 are the two crystal input con- nections. the output of the oscillator is buffered and avail- able at the osc output (pin 18) for generation of other system timing signals. for the most stable operation of the oscillator (osc) output circuit, two capacitors (c1 = c2) are recommended. capaci- tors c1 and c2 are chosen such that their combined capaci- tance matches the load capacitance as specified by the crystal manufacturer. this insures operation within the fre- quency tolerance specified by the crystal manufacturer. the crystal/capacitor configuration and the formula used to determine the capacitor values are shown in figure 4. crys- tal specifications are shown in table 3. frequency source selection the f/c input is a strapping pin that selects either the crystal oscillator or the efi input as the source frequency for clock generation. if the efi input is selected as the source, the oscillator section (osc output) can be used independently for another clock source. if a crystal is not used, then crystal input x1 (pin 23) must be tied to v cc or gnd and x2 (pin 22) should be left open. if the efi mode is not used, then efi (pin 20) should be tied to v cc or gnd. table 3. crystal specifications parameter typical crystal specification frequency 2.4 to 25mhz type of operation parallel resonant, fund. mode load capacitance 20 or 32pf rseries (max) 35x (f = 25mhz, c l = 32pf) 66x (f = 25mhz, c l = 20pf) ct c1 c2 ? c1 c2 + ---------------------- (including stray capacitance) = (eq. 1) c 1 c 2 x2 x1 crystal 2.4 - 25mhz figure 4. 82c85 crystal connection figure 5. slo /fst timing overview efi or osc pclk slo /fst clk clk50 82c85
305 clock generator the clock generator consists of two synchronous divide-by- three counters with special clear inputs that inhibit the count- ing. one counter generates a 33% duty cycle waveform (clk) and the other generates a 50% duty cycle waveform (clk50). these two counters are negative-edge synchro- nized, with the low-going transitions of both waveforms occurring on the same oscillator transition. the clk and clk50 output frequencies are one-third of the base input frequency when slo /fst is high and are equal to the base input frequency divided by 768 when slo /fst is low. the clk output is a 33% duty cycle clock signal designed to drive the 80c86 and 80c88 microprocessors directly. clk50 has a 50% duty cycle output synchronous with clk, designed to drive co-processors and peripherals requiring a 50% duty cycle clock. when slo /fst is high, clk and clk50 have output frequencies which are 1/3 that of efi/ osc. when slo /fst is low, clk and clk50 have output frequencies which are osc (efi) divided by 768. pclk is a peripheral clock signal with an output frequency equal to the oscillator or efi frequency divided by 6. pclk has a 50% duty cycle. pclk is unaffected by slo /fst. when the 82c85 is placed in the stop mode, pclk will remain in it?s current state (logic high or logic low) until a reset or start command restarts the 82c85 clock cir- cuitry. pclk is negative-edge synchronized with clk and clk50. clock synchronization the clock synchronization (csync) input allows the output clocks to be synchronized with an external event (such as another 82c85 or 82c84a clock signal). csync going active causes all clocks (clk, clk50 and pclk) to stop in the high state. it is necessary to synchronize the csync input to the efi clock external to the 82c85. this is accomplished with two flip-flops when synchronizing two 82c85s and with three flip- flops when synchronizing an 82c85 to an 82c84a (see fig- ure 6). multiple external flip-flops are necessary to minimize the occurrence of metastable (or indeterminate) states. ready synchronization two ready inputs (rdy1, rdy2) are provided to accom- modate two system busses. each ready input is qualified by (aen1 and aen2 , respectively). the aen signals vali- date their respective rdy signals. synchronization is required for all asynchronous active- going edges of either rdy input to guarantee that the rdy set up and hold times are met. inactive-going edges of rdy in normally ready systems do not require synchronization but must satisfy rdy setup and hold as a matter of proper sys- tem design. the async input defines two modes of ready synchroni- zation operation. when async is low, two stages of syn- chronization are provided for active ready input signals. positive-going asynchronous ready inputs will first be syn- chronized to flip-flop one at the rising edge of clk (requiring a setup time tr1vch) and then synchronized to flip-flop two at the next falling edge of clk, after which time the ready output will go high. negative-going asynchronous ready inputs will be syn- chronized directly to flip-flop two at the falling edge of clk, after which time the ready output will go inactive. this mode of operation is intended for use by asynchronous (nor- mally not ready) devices in the system which cannot be guaranteed by design to meet the required rdy setup timing (tr1vcl) on each bus cycle. when async is high or left open, the first ready flip-flop is bypassed in the ready synchronization logic. ready inputs are synchronized by flip-flop two on the falling edge of clk before they are presented to the processor. this mode is available for synchronous devices that can be guaranteed to meet the required rdy setup time. async can be changed on every bus cycle to select the appropriate mode of synchronization for each device in the system. efi 82c85 csync csync 82c84a csync with 82c85(s) clock sync efi dq > > > d q q d (to other 82c85s) figure 6. 82c85 and 82c84a csync synchronization methods 82c85
306 absolute maximum ratings thermal information supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +8.0v input, output or i/o voltage . . . . . . . . . . . gnd -0.5v to v cc +0.5v esd classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . class 1 operating conditions operating voltage range . . . . . . . . . . . . . . . . . . . . . +4.5v to +5.5v operating temperature range c82c85. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0 o c to +70 o c i82c85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40 o c to +85 o c m82c85 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 o c to +125 o c thermal resistance (typical) ja ( o c/w) jc ( o c/w) cerdip package . . . . . . . . . . . . . . . . . 70 16 ccc package . . . . . . . . . . . . . . . . . . . . 75 18 plcc package . . . . . . . . . . . . . . . . . . . 65 n/a storage temperature range . . . . . . . . . . . . . . . . .-65 o c to +150 o c maximum junction temperature ceramic package . . . . . . . +175 o c maximum junction temperature plastic package . . . . . . . . +150 o c (soldering 10s) maximum lead temperature (soldering 10s). . . . . . . . . . . . +300 o c (plcc - lead tips only) die characteristics gate count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 gates caution: stresses above those listed in ?absolute maximum ratings? may cause permanent damage to the device. this is a stress o nly rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not i mplied. dc electrical specifications v cc = 5.0v 10%; t a = 0 o c to +70 o c (c82c85); t a = -40 o c to +85 o c (i82c85); t a = -55 o c to +125 o c (m82c85) symbol parameter min max units test conditions v ih logical one input voltage 2.0 2.2 -v v c82c85, i82c85 m82c85 v ihr reset input high voltage 2.8 - v v il logical zero input voltage - 0.8 v note 1 v t + - v t reset input hysteresis 0.25 - v v oh logical one output voltage v cc -0.4 - v i oh = -5.0 ma (clk, clk50) i oh = -1.0ma (x2) i oh = -2.5ma (all other outputs) v ol logical zero output voltage - 0.4 v i ol = +2.5ma (x2) i ol = +5.0ma (all other outputs) ii input leakage current -1.0 1.0 av in = v cc or gnd, except dip pins 11 - 15, 21, 23 ibhh bus-hold high leakage current -10 -200 av in = 3.0v; pins 11 - 15, 21 iccsb standby power supply current - 100 a 82c85 in halt state with oscillator stopped iccop operating power supply current - 50 ma crystal frequency = 15mhz, outputs open, inputs = gnd or v cc - 70 ma crystal frequency = 25mhz, outputs open, inputs = gnd or v cc iccslow slow mode operating current - 40 ma crystal freq = 15mhz outputs open; slo /fst = gnd, start = v cc , other inputs - v in = v cc or gnd - 60 ma crystal freq = 25mhz note: 1. for csync, v il = gnd capacitance t a = 25 o c symbol parameter typical units test conditions c in input capacitance 15 pf freq = 1mhz, all measurements are referenced to device gnd c out output capacitance 20 pf 82c85
307 ac electrical specifications v cc = 5v 10%;t a = 0 o c to +70 o c (c82c85); t a = -40 o c to +85 o c (i82c85); t a = -55 o c to +125 o c (m82c85) symbol parameter limits units conditions min max timing requirements (1) tehel external frequency high time 15 - ns 90%-90% v in , note 1, f = 25mhz (2) teleh external frequency low time 15 - ns 10%-10% v in , note 1, f = 25mhz (3) telel efi or crystal period 40 - ns note 1 (4) tefidc external frequency input duty cycle 45 55 % f = 25mhz, note 1 (5) fx crystal frequency 2.4 25 mhz note 1 (6) tr1vcl rdy1, rdy2 active setup to clk 35 - ns async = high (7) tr1vch rdy1, rdy2 active setup to clk 35 - ns async = low (8) tr1vcl rdy1, rdy2 inactive setup to clk 35 - ns (9) tclr1x rdy1, rdy2 hold to clk 0 - ns (10) tayvcl async setup to clk 50 - ns (11) tclayx async hold to clk 0 - ns (12) ta1vr1v aen1 , aen2 setup to rdy1, rdy2 15 - ns (13) tcla1x aen1 , aen2 hold to clk 0 - ns (14) tyheh csync setup to efi 10 - ns (15) tehyl csync hold to efi 10 - ns (16) tyhyl csync pulse width 2telel - ns (17) ti1hcl res setup to clk 65 - ns note 2 (18) tsvch s0, s1, s2 /stop setup to clk 35 - ns (19) tchsv s0, s1, s2 /stop hold to clk 35 - ns (20) trsvch res , start setup to clk 65 - ns note 2 (21) tshsl res (low) or start (high) pulse width tclcls3 - ns (22) tsfpc slo /fst setup to pclk tehel + 100 - ns note 2 (23) tstart res or start valid to clk low 2telel + 2 - ns (24) tstop stop command valid to clk high 2tchch + trsvch 3tchch + 34 ns tchch = tclcl timing responses (25) tclcl clk/clk50 cycle period 125 - ns note 1 (26) tchcl clk high time (1/3 tclcl)+2 - ns 82c85
308 (27) tclch clk low time (2/3 tclcl)-15 - ns (28) t5chcl clk50 high time (1/2 tclcl)-7.5 - ns (29) t5clch clk50 low time (1/2 tclcl)-7.5 - ns (30) tch1ch2 clk/clk50 rise time - 8 ns 1.0v to 3.5v (31) tcl2cl1 clk/clk50 fall time - 8 ns 1.0v to 3.5v (32) tphpl pclk high time tclcl-20 - ns (33) tplph pclk low time tclcl-20 - ns (34) trylcl ready inactive to clk -8 - ns note 4 (35) tryhch ready active to clk 2/3(tclcl)-15 - ns note 3 (36) tclil clk to reset delay - 40 ns (37) tclph clk to pclk high delay - 22 ns (38) tclpl clk to pclk low delay - 22 ns (39) tost start/reset valid to clock low - 2 ms typ. - note 8 (40) toloh output rise time (except clk) - 15 ns from 0.8v to 2.0v (41) tohol output fall time (except clk) - 12 ns from 2.0v to 0.8v (42) trst reset output high time 16 x tclcl - ns (43) tclc50l clk low to clk50 low skew - 5 ns notes: 1. slow and fast modes. 2. setup and hold necessary only to guarantee recognition at next clock. 3. applies only to t3, tw states. 4. applies only to t2 states. 5. all timing delays are measured at 1.5v unless otherwise noted. 6. input signals must switch between v il max - 0.4 and v ih min + 0.4 volts 7. timing measurements made with efi duty cycle = 50%. 8. oscillator start up time depends on several factors including crystal frequency, crystal manufacturer, capacitive load, tempe rature, power supply voltage, etc. this parameter is given for information only. 9. output signals switch between v oh and v ol unless otherwise specified. ac electrical specifications v cc = 5v 10%;t a = 0 o c to +70 o c (c82c85); t a = -40 o c to +85 o c (i82c85); t a = -55 o c to +125 o c (m82c85) (continued) symbol parameter limits units conditions min max 82c85
309 timing waveforms figure 7. waveforms for clocks note: all timing measurements are made at 1.5v, unless otherwise noted. figure 8. waveforms for ready signals (for asynchronous devices) clk and clk50 1.0v 3.5v (30) tch1ch2 tcl2cl1 (31) tplph (33) tphpl (32) (37) tclph (28) t5chcl tclpl (38) t5clch (29) (26) tchcl tclch (27) tclc50l (43) teleh (2) (3) telel (1) tehel efi i osc 0 clk 0 clk50 0 pclk 0 csync i (15) tehyl (16) tyhyl (14) tyleh tclcl (25) clk rdy1.2 aen1.2 async ready (12) ta1vr1v (7) trivch (11) tclayx (34) trylcl (13) tcla1x (8) trilcl (9) tclr1x (35) tryhch (10) tayvcl (9) tclr1x 82c85
310 figure 9. waveforms for ready signals (for synchronous devices) figure 10. clock stop (f/c high or f/c low) note: when f/c is low, clk and clk50 stop high. when f/c is high, clk and clk50 may stop either high or low. timing waveforms (continued) (6) trivcl (9) tclrix (10) tayvcl (35) tryhch (34) trylcl (8) trilcl (9) tclr1x tcla1x (12) ta1vriv tclayx (13) (11) clk rdy1, 2 aen1, 2 async ready tstop (24) (18) tsvch (18) tsvch tchsx (19) trsvch (20) tchsx (19) (see note) efi clk clk50 pclk s0 s1 s2 /stop res start 82c85
311 figure 11. clocks start (f/c high) figure 12. clock start (f/c low) note: start up count begins when the crystal oscillator reaches a suitable threshold level. timing waveforms (continued) efi clk clk50 pclk s0 s1 s2 /stop res start (23) tstart (39) tost 8192 cycles crystal oscillator startup time (21) tshsl start x1 clk50 pclk clk 82c85
312 figure 13. reset timing (clk running with f/c low-osc mode) (clk running-or stopped with f/c high efi mode) figure 14. reset timing (oscillator stopped, f/c low) note: clk, clk50, pclk remain in the high state until res goes high and 8192 valid oscillator cycles have been registered by the 82c85 internal counter (tost time period). after res goes high and clk, clk50, pclk become active, the reset output will remain high for minimum of 16 clk cycles (trst). timing waveforms (continued) res clk reset (21) tshsl (17) ti1hcl (36) tclil (42) trst (36) tclil (17) ti1hcl res (21) tshsl clk reset oscillator startup time x1 (39) tost 8192 cycles (42) trst (36) tclil 82c85
313 figure 15. slo/fst timing overview note: see fast to slow clock mode transition for detailed timing; see slow to fast clock mode transition for detailed timing figure 16. fast to slow clock mode transition note: if tsfpc is not met on one edge of plck. slo/fst will be recognized on the next edge of plck. timing waveforms (continued) efi or osc pclk slo /fst clk clk50 efi or osc pclk tsfpc (22) (see note) slo /fst clk clk50 tsfpc (22) (see note) 197 to 200 efi or osc cycles 82c85
314 figure 17. slow to fast clock mode transition note: if tsfpc is not met on one edge of plck. slo/fst will be recognized on the next edge of plck. timing waveforms (continued) efi or osc pclk tsfpc (22) (see note) slo /fst clk clk50 tsfpc (22) (see note) 6 efi pulses 82c85
315 a.c. testing input, output waveform test load circuits passive load r = 360 at v = 2.25 for clk and clk50 outputs r = 470 at v = 2.87 for all other outputs (except x2) notes: 1. c l = 100pf for clk and clk50 output 2. c l = 50pf minimum for all other outputs 3. c l = includes probe and jig capacitance dynamic load i ol = 5ma, ioh = -5ma for clk and clk50 outputs i ol = 5ma, ioh = -2.5ma for all other outputs (except x2) i ol = 2.5ma, ioh = -1.0ma for x2 output (dc performance characteristic only) v trip = 1.4v tchcl, tclch load circuit (using x1, x2) tchcl, tclch load circuit (using efi) trylcl, tryhch load circuit (using x1, x2) trylcl, tryhch load circuit (using efi) v r from output under test cl see note 3 v r from output under test cl see note 3 c1 c2 x1 x2 csync clk f/c load (see note 1) load (see note 1) clk50 ef1 csync clk f/c v cc pulse generator load (see note 1) load (see note 1) clk50 c1 c2 x1 x2 clk load (see note 1) load (see note 2) csync f/c aen2 pulse generator trigger v cc 24mhz ready osc aen1 rdy2 ef1 clk load (see note 1) f/c v cc pulse generator csync rdy2 aen2 load (see note 2) aen1 ready trigger pulse generator input v ih + 0.4v v il + 0.4v 1.5v 1.5v v oh v ol output 82c85
burn-in circuits md82c85 cerdip mr82c85 clcc bottom view notes: 1. v cc = 5.5v 0.5v, gnd = 0v 2. v ih = 4.5v 10% 3. v il = -0.2 to 0.4v 4. r 1 = 100k ? , 5% 5. r 2 = 10k ? , 5% 6. r 3 = 47k ? , 5% 7. r 4 = 470k ? , 5% 8. c1 = 0.01 f (minimum) 9. f0 = 100khz 10% v cc c1 v cc v cc b nc nc v cc f0 v cc a v cc v cc gnd v cc a gnd a gnd v cc nc v cc gnd a v cc 16 17 18 19 20 21 22 23 24 15 14 13 1 2 3 4 5 6 7 8 9 10 11 12 v cc a v cc b r 1 r 2 r 2 r 2 r 2 r 2 r 2 r 2 r 2 r 2 r 2 r 3 r 4 r 4 1 f each input nc - no connect each board r 3 c2 v cc r 2 gnd r 2 r 2 r 2 r 2 v cc nc v cc f0 v cc a b nc r 2 r 2 r 2 r 2 nc nc agnd r 3 r 2 11 3 2 4 10 5 6 7 8 9 14 12 13 15 16 17 18 23 24 25 22 21 20 19 1 28 27 26 r 2 v cc ancv cc nc v cc gnd a gnd nc v cc v cc 82c85
317 all intersil u.s. products are manufactured, assembled and tested utilizing iso9000 quality systems. intersil corporation?s quality certifications can be viewed at www.intersil.com/design/quality intersil products are sold by description only. intersil corporation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnishe d by intersil is believed to be accurate and reliable. however, no responsibility is assumed by intersil or its subsidiaries for its use; nor for any infringements of paten ts or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiari es. for information regarding intersil corporation and its products, see www.intersil.com sales office headquarters north america intersil corporation 7585 irvine center drive suite 100 irvine, ca 92618 tel: (949) 341-7000 fax: (949) 341-7123 intersil corporation 2401 palm bay rd. palm bay, fl 32905 tel: (321) 724-7000 fax: (321) 724-7946 europe intersil europe sarl ave. william graisse, 3 1006 lausanne switzerland tel: +41 21 6140560 fax: +41 21 6140579 asia intersil corporation unit 1804 18/f guangdong water building 83 austin road tst, kowloon hong kong tel: +852 2723 6339 fax: +852 2730 1433 die characteristics die dimensions: 107.9 x 122.0 x 19 1mil metallization: type: si - al thickness: 11k ? 1k ? glassivation: type: sio 2 thickness: 8k ? 1k ? worst case current density: 2.26x 10 5 a/cm 2 this device meets glassivation integrity test requirements per mil-std-883 method 2021 metallization mask layout 82c85 aen1 pclk csync v cc x1 x2 async efi f/c osc res reset s2 /stop s1 s0 slo /fst start clk50 gnd clk aen2 rdy2 ready rdy1

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