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lm9070 low-dropout system voltage regulator with keep-alive on/off control general description the lm9070 is a 5v, 3% accurate, 250 ma low-dropout voltage regulator. the regulator features an active low delayed reset output flag which can be used to reset a microprocessor system on turn-on and in the event that the regulator output falls out of regulation for any reason. an external capacitor programs a delay time interval before the reset output can return high. designed for automotive application the lm9070 contains a variety of protection features such as reverse battery, over-voltage shutdown, thermal shutdown, input transient protection and a wide operating temperature range. a unique two-input logic control scheme is used to enable or disable the regulator output. an on/off input can be provided by an ignition switch derived signal while a second, keep-alive input, is generated by a system controller. this allows for a system to remain on after ignition has been switched off. the system controller can then execute a power-down routine and after which command the regulator off to a low quiescent current state (60 a max). design techniques have been employed to allow the regulator to remain operational and not generate false reset signals when subjected to high levels of rf energy (300v/m from 2 mhz to 400 mhz). features n automotive application reliability n 3% output voltage tolerance n insensitive to radiated rfi n dropout voltage less than 800 mv with 250 ma output current n externally programmed reset delay interval n keep-alive feature with 2 logic control inputs n 60v load dump transient protection n thermal shutdown n short circuit protection and disable safety features n reverse battery protection n low off quiescent current, 50 a maximum n wide operating temperature range ?40c to +125c n to-263 and 20-pin power surface mount packages n lead form compatible with tle4267 to-220 regulator (package ta07d) connection diagrams and ordering information (top view) 7-lead to-263 surface mount package ds012831-1 backside metal is internally connected to ground. order number lm9070s see ns package number ts7b 20-pin so package ds012831-2 order number lm9070m see ns package number m20b march 2001 lm9070 low-dropout system voltage regulator with keep-alive on/off control ? 2001 national semiconductor corporation ds012831 www.national.com
connection diagrams and ordering information (top view) (continued) 7-lead to-220 package (odd numbered pins bent forward away from package body) ds012831-3 tab is internally connected to ground. order number lm9070t see ns package number ta07b 7-lead to-220 package (even numbered pins bent forward away from package body) ds012831-4 tab is internally connected to ground. order number lm9070t/flow lb09 see ns package number ta07d lm9070 www.national.com 2 absolute maximum ratings (note 1) input voltage, dc ?26v to +40v on/off, keep-alive inputs (through 1k w ) ?26v to +26v positive input transient (t < 100 ms) 60v negative input transient (t < 1 ms) ?50v reset output sink current 5 ma power dissipation internally limited junction temperature 150c esd susceptibility (note 2) 12 kv, 2 kv lead temperature (soldering, 10 seconds) 260c storage temperature ?50c to +150c operating ratings (note 1) input voltage 6v to 26v ambient temperature ?40c to +125c to-220 thermal resistance, q j-c 3c/w to-220 thermal resistance, q j-a (note 3) 73c/w to-263 thermal resistance, q j-c 3c/w to-263 thermal resistance, q j-a (note 4) 80c/w so20 thermal resistance, q j-pins 25c/w so20 thermal resistance, q j-a 85c/w electrical characteristics (note 5) the following specifications apply for v cc = 6v to 26v, ?40c t a 125c, unless otherwise specified. c out =47f with an esr < 3 w .c in = 1f. symbol parameter conditions min max units regulator output v out output voltage 5 ma i out 250 ma 4.85 5.15 v d v out line line regulation i out = 5 ma, 9v v in 16.5v i out = 5 ma, 6v v in 26v 25 50 mv mv d v out load load regulation v in = 14.4v, 5 ma i out 250 ma 50 mv iq quiescent current v on/off v in i out =5ma i out = 250 ma, v in 3 8v i out = 5 ma, v in =5v i out = 250 ma, v in =6v 4 25 10 50 ma ma ma ma ioff off quiescent current v in 16.5v, regulator off ?40c t j 60c 60c t j 135c 20 60 a a vdo dropout voltage i out =5ma i out = 250 ma 300 800 mv mv isc short circuit current r l =1 w 0.4 1.5 a psrr ripple rejection v in = (14v dc )+1v rms @ 120h z ) i out =50ma 60 db voth off safety v out latch-off threshold in keep-alive mode v on/off = 0v, v ka = 0v 4 4.5 v ovthr overvoltage shutdown threshold 27 v vo transient v out during transients v in peak 60v, r l = 100 w , t = 100 ms 7v reset output vth threshold voltage d v out required to generate a reset output 4.85v v out 5.15v ?300 ?500 mv vlow reset output low voltage isink = 1.6 ma, v out > 3.2v 0.4 v 1.4v v out 3.2v 0.8 v vhigh reset output high voltage 0.9 v out v out v t delay delay time c delay = 0.1f 7 31 ms i delay charging current for c delay 10 30 a rpu internal pull-up resistance 12 80 k w control logic v ka low low input threshold voltage, keep-alive input 3.5v v out 5.25v 0.3 v out 0.5 v out v lm9070 www.national.com 3 electrical characteristics (note 5) (continued) the following specifications apply for v cc = 6v to 26v, ?40c t a 125c, unless otherwise specified. c out =47f with an esr < 3 w .c in = 1f. symbol parameter conditions min max units control logic v ka high high input threshold voltage, keep-alive input 3.5v v out 5.25v 0.6 v out 0.8 v out v v on/off low low input voltage, on/off input rseries = 1 k w ?2 2 v v on/off high high input voltage, on/off input rseries = 1 k w 426v i on/off input current, on/off input v on/off 4v 330 a 4v < v on/off < 7v 670 a v on/off 3 7v 10 ma rpu ka internal pull-up resistance, keep-alive input 0v v in 26v 20 100 k w rpd on/off internal pull-down resistance on/off input 0v v on/off 26v 50 210 k w note 1: absolute maximum ratings indicate limits beyond which damage to the device may occur. operating ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. for guaranteed specifications and conditions, see the electrical characteristics. note 2: all pins will survive an esd impulse of 2000v using the human body model of 100 pf discharged through a 1.5 k w resistor. in addition, input pins v in and the on/off input will withstand ten pulses of 12 kv from a 150 pf capacitor discharged through a 560 w resistor with each pin bypassed with a 22 nf, 100v capacitor. note 3: exceeding the maximum allowable power dissipation will cause excessive die temperature, and the device will go into thermal shutdown. the q j-a value for the to-220 package (still air, no additional heat sink) is 73c/w. the effective q j-a value of the to-220 package can be reduced by using conventional heat sink methods. note 4: exceeding the maximum allowable power dissipation will cause excessive die temperature, and the device will go into thermal shutdown. the q j-a value for the to-263 package (still air, no additional heat sink) is 80c/w. the effective q j-a value of the to-263 package can be reduced by increasing the printed circuit board area that is connected (soldered) to the package tab. using 1 ounce (1.4 mils thick) copper clad with no solder mask, an area of 0.5 square inches wi ll reduce q j-a to 50c/w, an area of 1.0 square inches will reduce q j-a to 37c/w, ad an area of 1.6 square inches will reduce q j-a to 32c/w. if the printed circuit board uses a solder mask, the copper clad area should be increased by at least 50% to maintain a similar q j-a rating. note 5: datasheet min/max specifications are guaranteed by design, test, and/or statistical analysis. reset operation and protection features ds012831-5 lm9070 www.national.com 4 typical performance characteristics (t a = 25c unless indicated otherwise) turn on characteristics ds012831-6 turn off characteristics ds012831-7 normalized output voltage vs temperature ds012831-8 output voltage at input voltage extremes ds012831-9 quiescent current vs input voltage ds012831-10 input current vs input voltage regulator switched off ds012831-11 dropout voltage vs temperature ds012831-12 reset delay time vs temperature ds012831-13 short circuit current vs temperature ds012831-14 lm9070 www.national.com 5 typical performance characteristics (t a = 25c unless indicated otherwise) (continued) on/off, keep-alive and safety latch-off control diagrams note: if keep-alive is provided by a microprocessor powered by the output voltage of the lm9070, the logic a1o voltage level will track v out as the regulator turns off. output capacitor esr ds012831-15 maximum power dissipation (to-220 package) ds012831-16 maximum power dissipation (to-263 and so-20 packages) ds012831-17 simple on/off control (keep-alive input must be high to turn off output) ds012831-18 keep-alive mode; turn on with on/off control, keep output biased with keep-alive input, turn off with keep-alive (keep-alive low keeps output on, keep-alive going high turns output off) ds012831-19 switch on with on/off input; keep output biased with keep-alive; hold ouput on with on/off; turn off with on/off input. (temporary keep-alive mode) ds012831-20 safety latch off of v out when in keep-alive mode (on/off going high required to turn output back on) ds012831-21 lm9070 www.national.com 6 control logic truth table on/off input keep-alive input output voltage reset output operating condition l x 0v l low quiescent current standby (off) condition - x5v - after delay output turns on h x 5v h normal on condition h 0v l output turns off l 5v h output kept on by keep-alive input - l 5v h output remains on (or turns on) hx d v out 3 ?300 mv l output pulled out of regulation, reset flag generated ll v out 4v l output latches off block diagram application information the lm9070 voltage regulator has been optimized for use in microprocessor based automotive systems. several unique design features have been incorporated to address many fmea (failure mode effects analysis) concerns for fail-safe system performance. fault tolerant features while not specifically guaranteed due to production testing limitations, the lm9070 has been tested and shown to continue to provide a regulated output and, not generate an erroneous system reset signal while subjected to high levels of rf electric field energy (up to 300 v/m signal strength over a 2 mhz to 400 mhz frequency range). this is very important in vehicle safety related applications where the system must continue to operate normally. to maintain this immunity to rfi the output bypass capacitor is important (47 f is recommended). this regulator is suitable for applications where continuous connection to the battery is required ( refer to the typical application circuit ). on/off control of the regulator and system can be accomplished by switching the on/off input to the battery or ignition supply v in supply through a spst switch. if this input becomes open circuited, an internal pull-down resistor ensures that the regulator turns off. when the regulator is switched off the current load on the battery drops to less than 60 a. with the possibility in many applications for v in and the on/off input pins to be connected in a system through long lengths of wire, the esd protection of these pins has been increased to 12 kv with the addition of small input bypass capacitors. ds012831-22 ds012831-23 figure 1. typical application circuit lm9070 www.national.com 7 application information (continued) an output bypass capacitor of at least 10 f is required for stability (47 f is recommended). the esr of this capacitor should be less than 3 w . an input capacitor of 1 f or larger is recommended to improve line transient and noise performance. with the keep-alive input, a system microprocessor has the ability to keep the regulator on (with a logic a0o on keep-alive) after the on/off input has been commanded off. a power-down sequence, when system variables are typically stored in programmable memory, can be executed and take as much time as necessary. at the end of the operation the micro then pulls keep-alive high and the regulator and system turn off and revert to the low quiescent current standby mode. for additional system reliability, consideration has been made for the possibility of a short circuited load at the output of the regulator. when the regulator is switched on, conventional current limiting and thermal shutdown protect the regulator. when the regulator is switched off however, a grounded v cc supply to the micro (due to the shorted regulator output) will force the keep-alive input to be low and thus try to maintain the keep-alive mode of operation. with a shorted load, the drain on the battery could be as high as 1.5a. a separate internal circuit monitors the output voltage of the regulator. if v out is less than 4v, as would be the case with a shorted load, the keep-alive function is logically disabled to ensure that the regulator turns off and reverts to only a 50 a load on the battery. conventional load dump protection is built in to withstand up to +60v and ?50v transients. a 1 k w resistor in series with the on/off and keep-alive inputs are recommended to provide the same level of transient protection for these pins if required. protection against reverse polarity battery connections is also built in. with a reversed battery the output of the lm9070 will not go more negative than one diode drop below ground. this will prevent damage to any of the 5v load circuits. for applications where the control logic is not required the logic pins should be configured as shown in figure 2 .a separate device, called the lm9071, can be used. the lm9071 is available in a 5-lead to-220 package and does not provide control logic functions, but still retains all of the protection features of the lm9070. reset flag excessive loading of the output to the point where the output voltage drops by 300 mv to 500 mv will signal a reset flag to the micro. this will warn of a v cc supply that may produce unpredictable operation of the system. on power-up and recovery from a fault condition the delay capacitor is used to hold the micro in a reset condition for a programmable time interval to allow the system operating voltages and clock to stabilize before executing code. the typical delay time interval can be estimated using the following equation: input stability low dropout voltage regulators which utilize a pnp power transistor usually exhibit a large increase in current when in dropout (v in < 5.5v). this increase is caused by the saturation characteristics ( b reduction) of the pnp transistor. to significantly minimize this increase in current the lm9070 detects when the pnp enters saturation and reduces the operating current. this reduction in input current can create a stability problem in applications with higher load current ( > 100 ma) where the input voltage is applied through a long length of wire, which in effect adds a significant amount of inductance in series with the input. the drop in input current may create a positive input voltage transient which may take the pnp out of saturation. if the input voltage is held constant at the threshold where the pnp is going in and out of saturation, an oscillation may be created. this is only observed where significant series inductance is present in the input supply line and when the rise and fall time of the input supply is very slow. if the application and removal of the input voltage changes at a rate greater than 500 mv/s, the input voltage moves through the dropout region of operation (v in of 3v to 5.5v) too quickly for an oscillation to be established. microprocessor system regulator with keep-alive interval at turn-off the following circuit illustrates a system application utilizing both of the logic control inputs of the lm9070. closing the on/off switch powers on the system. once powered, the system controller sets the keep-alive line low. the npn transistor is used only to signal the controller that the on/off switch has been opened and the system is to be turned off. upon detecting this high level at the on/off sense input line, the controller can then perform a power down routine. the system will remain fully powered until the controller commands total shut down by taking the keep-alive line high. the system then shuts off and reverts to a very low current drain standby condition until switched back on. ds012831-24 figure 2. control logic not used lm9070 www.national.com 8 application information (continued) thermal management the lm9070 is packaged in both a to-263 surface mount power package and a narrow lead-pitch to-220 package. to obtain operation over the highest possible load current and input voltage ranges, care must be taken to control the operating temperature of the device. thermal shutdown protection is built in, with a threshold above 150c. conventional heat-sinking techniques can be used with the to-220 package. when applying the to-263 package, on board heat-sinking is important to prevent premature thermal shutdown. more copper foil area under the tab of the device will directly improve the operating q j-a of the to-263 package, which will reduce the junction temperature of the device. the q j-a value for the to-263 package (still air, no additional heat sink) is rated at 80c/w. the effective q j-a value of the to-263 package can be reduced by increasing the printed circuit board area that is connected (soldered) to the ds012831-25 lm9070 www.national.com 9 application information (continued) package tab. using 1 ounce (1.4 mils thick) copper clad with no solder mask, an area of 0.5 square inches will reduce q j-a to 50c/w, an area of 1.0 square inches will reduce q j-a to 37c/w, and an area of 1.6 square inches will reduce q j-a to 32c/w. if the printed circuit board uses a solder mask, the copper clad area under the solder mask should be increased by at least 50% to maintain a similar q j-a rating. the use of a double sided pc board with soldered filled vias between two planes of copper, as shown in figure 3, will improve thermal performance while optimizing the pc board surface area required. using the double sided pc board arrangement shown in figure 3, with 1 ounce (1.4 mils thick) copper clad with no solder mask and solder filled vias, an area of 0.5 square inches on both sides will reduce q j-a to 43c/w. ds012831-27 figure 3. typical to-263 pc board heatsinking lm9070 www.national.com 10 physical dimensions inches (millimeters) unless otherwise noted 20-lead (0.300" wide) molded small outline package, jedec order number lm9070m ns package number m20b lm9070 www.national.com 11 physical dimensions inches (millimeters) unless otherwise noted (continued) 7-lead molded to-220 order number lm9070t ns package number ta07b lm9070 www.national.com 12 physical dimensions inches (millimeters) unless otherwise noted (continued) 7-lead molded to-220 order number lm9070t/flow lb09 ns package number ta07d 7-lead molded to-263 order number lm9070s ns package number ts7b lm9070 www.national.com 13 notes life support policy national's products are not authorized for use as critical components in life support devices or systems without the express written approval of the president and general counsel of national semiconductor corporation. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. a critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. national semiconductor corporation americas tel: 1-800-272-9959 fax: 1-800-737-7018 email: support@nsc.com national semiconductor europe fax: +49 (0) 180-530 85 86 email: europe.support@nsc.com deutsch tel: +49 (0) 69 9508 6208 english tel: +44 (0) 870 24 0 2171 fran?ais tel: +33 (0) 1 41 91 8790 national semiconductor asia pacific customer response group tel: 65-2544466 fax: 65-2504466 email: ap.support@nsc.com national semiconductor japan ltd. tel: 81-3-5639-7560 fax: 81-3-5639-7507 www.national.com lm9070 low-dropout system voltage regulator with keep-alive on/off control national does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and national reserves the righ t at any time without notice to change said circuitry and specifications. |
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