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power management 1 sc620 octal led driver, general purpose current sink with serial interface ? 2007 semtech corporation features wide current setting range 31.25a to 25ma eight identical current drivers with independent control 5% current matching, 7% accuracy i 2 c interface for microprocessor control i 2 c slave address 1110 000x less than 1a quiescent current in shutdown low dropout voltage 150mv over-temperature protection mlpq-ut-16 package (3mm x 3mm) ultra-thin 0.6mm maximum package height fully weee and rohs compliant applications lcd backlighting led driver multicolor and rgb led driver general purpose current sink array general purpose digital output (open-drain) expander auto-focus voice-coil driver ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? description the sc620 is a multi-purpose led driver with eight identi- cal, independently controlled current sinks. each current sink can drive an led by connecting the leds anode to the system power supply and the cathode to the current sink input pin. any combination of outputs can be enabled or disabled for optimal design fl exibility. the sc620 also employs an adjustable global current gain setting register to allow the current setting step size to vary from 31.25a to 500a. this provides a wide range of options for led variation and dimming functions. the maximum output is also scaled by this step size, with a maximum of 25ma at the highest step setting. multi-colored and white leds with diff erent forward volt- ages can be driven using the same sc620 due to its fl oat- ing cathode technology. this feature allows each output pin to vary in voltage from 150mv to v in - 1.5v. all current control is programmed using an i 2 c interface bus. only a single input bypass capacitor is required no other external resistors or capacitors are needed. the 3mm x 3mm mlpq package and minimal support components make the sc620 an ideal solution for low-cost, area-con- scious backlighting designs. battery sc620 in scl sda en gnd gnd gnd gnd iled1 iled2 iled3 iled4 iled6 i l e d 7 iled8 iled5 sub panel color/r/g/b leds 1 f scl sda en main panel led backlighting typical application circuit december 19, 2007
sc620 2 pin confi guration marking information ordering information device package sc620ultrt (1)(2) mlpq-ut-16 33 (2) sc620evb evaluation board notes: (1) available in tape and reel only. a reel contains 3,000 devices. (2) lead-free package only. device is weee and rohs compliant. top view 1 2 3 4 12 11 10 9 16 15 14 13 5678 t gnd gnd gnd gnd in en scl sda iled1 iled2 iled3 iled4 iled8 iled7 iled6 iled5 620 yyww xxxx mlpq-ut-16; 3x3, 16 lead ja = 39c/w yy = two digit year of manufacture ww = two digit week of manufacture xxxx = lot number
sc620 3 exceeding the above specifi cations may result in permanent damage to the devic e or device malfunction. operation outside of the parameters specifi ed in the electrical characteristics section is not recommended. notes: (1) tested according to jedec standard jesd22-a114-b. (2) calculated from package in still air, mounted to 3 x 4.5 (in), 4 layer fr4 pcb with thermal vias under the exposed pad per jesd51 standards. absolute maximum ratings in (v) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 pin voltage all other pins (v) . . . . . . . . . -0.3 to v in + 0.3 esd protection level (1) (kv) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 recommended operating conditions ambient temperature range (c) . . . . . . . . . . . . -40 to +85 thermal information thermal resistance, junction to ambient (2) (c/w) . . . . 39 operating junction temperature (c) . . . . . . . . -40 to +150 storage temperature range (c) . . . . . . . . . . . -65 to +150 peak ir refl ow temperature (10s to 30s) (c) . . . . . . . +260 unless otherwise noted, t a = +25c for typ, -40oc to 85c for min and max, v in = 2.7v to 5.5v, c in = 1f, v f 1.5v parameter symbol condition min typ max units maximum led current setting (1) i ledn 25 ma led current setting accuracy (1) i ledn i ledn = 15ma, v f = 3.4v, v iledn = 2v, t a = 25oc -7 +7 % load regulation i ledn / v f 5ma < i ledn 25ma, t a = 25oc -2 2 % / v led current matching accuracy (1) i led-to-led i ledn = 15ma, t a = 25oc -5 +5 % dropout voltage v do i ledn = 25ma 150 mv shutdown current i shdn en = gnd 0.1 1 a current step size i step normal mode (3) 500 a low-current mode (4) 31.25 a quiescent current i q standby: en = v in , led1-8 disabled (2) 60 a en = v in , i led1-8 = 1.968ma (4) 720 a en = v in , i led1-8 = 25ma (3) 4.5 ma electrical characteristics
sc620 4 parameter symbol condition min typ max units current sink turn-on time t on from 0 to 95% of target 1 ms current sink turn-off time t off from 90% to 10% of set value 1 s en input high threshold v ih v in = 5.5v 1.6 v en input low threshold v il v in = 2.7v 0.4 v en input high current i ih v in = 5.5v 2 a over temperature protection (5) t otp 155 c i 2 c interface (5) interface complies with slave mode i 2 c interface as described by philips i 2 c specifi cation version 2.1 dated january, 2000. digital input voltage v b-il 0.4 v v b-ih 1.6 v sda output low level i din (sda) 3ma 0.4 v digital input current i b-in -0.2 0.2 a schmitt trigger input hysteresis v hys 0.1 v maximum glitch pulse rejection t sp 50 ns i/o pin capacitance c in 10 pf i 2 c timing clock frequency f scl 400 440 khz scl low period t low 1.3 s scl high period t high 0.6 s data hold time t hd_dat 0s data setup time t su_dat 100 s setup time for repeated start condition t su_sta 0.6 s hold time for repeated start condition t hd_sta 0.6 s setup time for stop condition t su_sto 0.6 s electrical characteristics (continued)
sc620 5 electrical characteristics (continued) parameter symbol condition min typ max units i 2 c timing (continued) bus-free time between stop and start t buf 1.3 s interface start-up time t en bus start-up time after en pin is pulled high 350 s notes: (1) current step size = 500a - see table 1 for other step size options. (2) outputs are disabled but i 2 c bus is active (3) current gain register set to maximum value - see control register section for details. (4) current gain register set to minimum value - see control register section for details. (5) guaranteed by design.
sc620 6 typical characteristics low current settings with anode = v in 0 100 200 300 400 500 600 2.5 3 3.5 4 4.5 5 5.5 led current ( a) boundary of cathode = 150mv 500 a,v f = 2.80v anode supply = v in v in (v) 250 a,v f = 2.73v 125 a,v f = 2.68v 31.25 a,v f = 2.59v mid current settings with anode = v in 4 6 8 10 12 14 16 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 led current (ma) anode supply = v in 15ma,v f = 3.27v v in ( v ) 10ma,v f = 3.20v 5ma,v f = 3.08v boundary at cathode = 150mv high current settings with anode = v in 8 11 14 17 20 23 26 3.25 3.5 3.75 44.254.5 4.75 5 5.25 5.5 led current (ma) v in (v) boundary at cathode = 150mv anode supply = v in 25ma,v f = 3.37v 15ma,v f = 3.27v 10ma,v f = 3.20v low current settings with anode = 5v 0 100 200 300 400 500 600 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 v in (v) led current ( a) anode supply = 5v 500 a,v f = 2.79v boundary of cathode at v in -1.5v 250 a,v f = 2.73v 125 a,v f = 2.68v 31.25 a,v f = 2.59v mid current settings with anode = 5v 4 6 8 10 12 14 16 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 led current (ma) anode supply = 5v 15ma,v f = 3.26v v in (v) boundary of cathode at v in -1.5v 10ma,v f = 3.19v 5ma,v f = 3.08v high current settings with anode = 5v 8 11 14 17 20 23 26 33.25 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 led current (ma) v in (v) anode supply = 5v 10ma,v f = 3.19v 15ma,v f = 3.26v 25ma,v f = 3.35v boundary of cathode at v in -1.5v
sc620 7 typical led current matching -3.5 -2.5 -1.5 -0.5 0.5 1.5 2.5 3.5 0.5 5.5 10.5 15.5 20.5 25.5 led current (ma) % matching gain register value = 0ch -40 c 25 c 85 c typical led current accuracy (25c) -8 -6 -4 -2 0 2 4 6 8 0.5 5.5 10.5 15.5 20.5 25.5 % accuracy led current (ma) all 8 leds fall between max and min, gain register value = 0ch max min typical led current accuracy (85c) -8 -6 -4 -2 0 2 4 6 8 0.5 5.5 10.5 15.5 20.5 25.5 % accuracy led current (ma) all 8 leds fall between max and min, gain register value = 0ch max min typical led current accuracy (-40c) -8 -6 -4 -2 0 2 4 6 8 0.5 5.5 10.5 15.5 20.5 25.5 led current (ma) % accuracy all 8 leds fall between max and min, gain register value = 0ch max min
sc620 8 pin descriptions pin # pin name pin function 1 gnd ground 2 in input voltage supply 3 en enable input active high 4 gnd ground 5 iled1 current sink input for led 1 6 iled2 current sink input for led 2 7 iled3 current sink input for led 3 8 iled4 current sink input for led 4 9 gnd ground 10 sda i 2 c serial data pin (bi-directional) 11 scl i 2 c clock input 12 gnd ground 13 iled5 current sink input for led 5 14 iled6 current sink input for led 6 15 iled7 current sink input for led 7 16 iled8 current sink input for led 8 t thermal pad thermal pad for heatsinking purposes. connect to ground plane using multiple vias. not connected internally.
sc620 9 block diagram gnd iled1 dac dac dac dac dac digital interface and control registers voltage reference dac dac dac in en sda scl iled2 iled3 iled4 iled5 iled6 iled7 iled8 gnd gnd gnd v in v in 11 v in v in v in v in v in v in v in 2 1 3 10 12 16 15 13 14 5 6 7 8 9 4
sc620 10 general description the sc620 includes eight independently controlled current sinks designed to control led backlighting for mobile phones and other battery-operated handheld devices. as led forward voltages decrease for white, blue, and other colored leds, there is less need for voltage boosting devices for powering backlight and indicator leds. in these types of systems where there is a fixed supply voltage large enough to supply the leds or where the leds can be powered over the entire battery range, the sc620 provides a simple low-cost driver alternative to charge pump or inductor-based switching boost converters. current sink design each current sink is designed for a pin voltage range between 150mv and v in - 1.5v. this feature allows the system to operate backlight leds with constant current without interference caused by blinking indicator leds or driving leds with various forward voltages and currents. protection circuitry the sc620 contains protection circuitry that prevents damage from operating in an unspecified state. these features include: under-voltage lockout protection over-temperature protection short-circuit protection under-voltage lockout an under-voltage lockout protection (uvlo) circuit dis- ables the device in the event that the input voltage falls below the threshold. uvlo typically occurs at 2v. hysteresis is provided to prevent chatter. short-circuit protection the output sink pins iled1 through iled8 are protected against shorting to v in , prevent device damage in the event of a shorted led. the source lead of each sink is con- nected to ground, so the output sink pins do not require protection against being externally shorted to ground, as this would result in zero potential across the sink device. over-temperature protection the over-temperature protection circuit helps prevent the device from overheating and experiencing a catastrophic ? ? ? failure. when the junction temperature exceeds 155c, the device is disabled and remains disabled until the junction temperature drops by the hysteresis value. layout considerations the mlpq-ut-16 package has a thermal die attach pad located at the center. this pad must be connected to the ground plane through multiple vias as shown (illustration not to scale). scl v in c in sc620 gnd gnd iled1 iled2 iled3 iled4 iled5 iled6 iled7 iled8 sda gnd gnd gnd en ground plane for low noise, four ground pins are located at the corner pins 1, 4, 9 and 12. connect each of the ground pins directly to the ground plane as shown. the layout is simple and requires very few components in addition to the leds that it will drive. a 1f decoupling capacitor at the in pin is required. place this capacitor near pin 2, and ground it close to the sc620 as shown. applications information
sc620 11 applications information (continued) application circuit examples main backlight plus sub-panel backlight plus single rgb led this example uses the sc620 to drive a main display, a sub-panel display, and an rgb led. independent outputs allow these functions to be supported simultaniously at diff erent intensities. the v in supply is typically single cell li-ion or 5.0v. v in supply and led anode voltage may be from diff erent sources. the operating voltage limit of (v in 1.5v) at the sink pins must be observed to achieve the specifi ed accuracy of the device. battery sc620 in scl sda en gnd gnd gnd gnd iled1 iled2 iled3 iled4 iled6 i l e d 7 iled8 iled5 sub panel color/r/g/b leds 1 f scl sda en main panel led backlighting 2 11 5 6 10 7 13 8 1 3 14 15 16 12 9 4
sc620 12 backlighting three leds of any color combination plus lens voice coil drive and one gpo this example uses the sc620 to drive 3 backlight leds, plus a voice coil actuator for lens auto-focus and one open-drain digital output. independent outputs allow these functions to be supported simultaneously. the v in supply is typically single cell li-ion or 5.0v. v in and the led anode voltage may be supplied by diff erent sources. the operating voltage limit of (v in 1.5v) at the sink pins must be observed to achieve the specifi ed accuracy of the device. sc620 in 2 scl 11 sda 10 en 3 gnd 1 gnd 4 gnd 9 gnd 12 iled1 5 iled2 6 iled3 7 iled4 8 iled6 14 iled8 16 iled5 13 v logic 1 f scl sda en main panel led backlighting lens focusing v bat = 2.7v to 5.5v v bat voice coil iled7 15 gpo digital output expander applications information (continued)
sc620 13 applications information (continued) backlighting with series connected leds connected to a boosted output voltage this example uses the sc620 to drive 32 leds in a 4-in- series by 8-in-parallel arrangement. other arrangements of series and parallel combinations are possible. to prevent the boost voltage from illuminating the leds while the current sinks are off, the boost voltage must follow the sc620 in the start-up sequence. the boost voltage must also power-off before the current sinks turn off in the shut-down sequence. protection diodes may be necessary to protect the current sinks from destructive voltage levels produced by the boost voltage supply. schottky diodes are shown in the schematic for the purpose of voltage clamping. these diodes prevent damage to the current sinks in the event that the sink turns off while the boost circuit is on. the operating voltage limit of (v in 1.5v) at the sink pins must be observed to achieve the specifi ed accuracy of the device. sc620 in 2 scl 11 sda 10 en 3 gnd 1 gnd 4 gnd 9 gnd 12 iled1 5 iled2 6 iled3 7 iled4 8 iled6 14 i l e d 7 1 5 iled8 16 iled5 13 1 f scl sda en led backlighting 5v r 1 r 2 = (3/7)*(r 1 ) limit sc620 sink pins to < [vin ? 1.5] + - dc/dc boost voltage boost limiting
sc620 14 register map sc620 slave address following a start condition, the bus master outputs the address of the slave device. the 7 bit slave address for the sc620 is 1110 000x. the eighth bit is the data direction bit and also the least signifi cant bit (lsb). e0h is used for a write operation, and e1h is used for a read operation. device address r/w 11100001/0 dimming control register description the dimming control registers set the multiplier used to determine the absolute current setting. current setting for each current sink is determined by multiplying the current step size (as described in table 1) by the decimal multiplier in each dimming control register. for example, if the current step size is set to 500a and the l1 dimming control register bits (l1_5 through l1_0) are set to 010100 (20 decimal), then the output current for iled1 is set to 20 x 500a = 10ma. note that the maximum current setting occurs when the dimming control register bits are set to 110010 (50 decimal) - any bit combination larger than this one will default to the maximum setting. address d7 d6 d5 d4 d3 d2 d1 d0 description default (1) 00h l8_en 1 = on 0 = off l7_en 1 = on 0 = off l6_en 1 = on 0 = off l5_en 1 = on 0 = off l4_en 1 = on 0 = off l3_en 1 = on 0 = off l2_en 1 = on 0 = off l1_en 1 = on 0 = off led on/off control 00h 01h x x l1_5 l1_4 l1_3 l1_2 l1_1 l1_0 led1 dimming control 01h 02h xx l2_5 l2_4 l2_3 l2_2 l2_1 l2_0 led2 dimming control 01h 03h xx l3_5 l3_4 l3_3 l3_2 l3_1 l3_0 led3 dimming control 01h 04h xx l4_5 l4_4 l4_3 l4_2 l4_1 l4_0 led4 dimming control 01h 05h xx l5_5 l5_4 l5_3 l5_2 l5_1 l5_0 led5 dimming control 01h 06h xx l6_5 l6_4 l6_3 l6_2 l6_1 l6_0 led6 dimming control 01h 07h xx l7_5 l7_4 l7_3 l7_2 l7_1 l7_0 led7 dimming control 01h 08h xx l8_5 l8_4 l8_3 l8_2 l8_1 l8_0 led8 dimming control 01h 09h xx x x g4 g3 g2 g1 gain register 08h note (1) default value is the register contents immediately following a high transition at the enable pin. table 1 - gain setting values (default = 1000) g4 g3 g2 g1 current step size (a) 0000 31.25 0001 62.5 0010 93.75 0011 125 0100 156.25 0101 187.5 0110 218.75 0111 250 1000 281.25 1001 312.5 1010 343.75 1011 375 1100 406.25 1101 437.5 1110 468.75 1111 500
sc620 15 using the i 2 c serial port the i 2 c general specifi cation the sc620 is a read-write slave-mode i 2 c device and com- plies with the philips i 2 c standard version 2.1 dated january, 2000. the sc620 has eight user-accessible inter- nal 8-bit registers. while there is no auto increment/decre- ment capability in the sc620 i 2 c logic, a tight software loop can be designed to randomly access the next register independent of which register you begin accessing. the start and stop commands frame the data-packet and the repeat start condition is allowed if necessary. sc620 limitations to the i 2 c specifi cations seven bit addressing is used and ten bit addressing is not allowed. any general call address will be ignored by the sc620. the sc620 is not cbus compatible. the sc620 can operate in standard mode (100kbit/s) or fast mode (400kbit/s). supported formats: direct format write the simplest format for an i 2 c write is direct format. after the start condition [s], the slave address is sent, followed by an eighth bit indicating a write. the sc620 i 2 c then acknowledges that it is being addressed, and the master responds with an 8 bit data byte consisting of the register address. the slave acknowledges and the master sends the appropriate 8 bit data byte. once again the slave acknowledges and the master terminates the transfer with the stop condition [p]. combined format read after the start condition [s], the slave address is sent, fol- lowed by an eighth bit indicating a write. the sc620 i 2 c then acknowledges that it is being addressed, and the master responds with an 8 bit data byte consisting of the register address. the slave acknowledges and the master sends the repeated start condition [sr]. once again, the slave address is sent, followed by an eighth bit indicating a read. the slave responds with an acknowledge and the previously addressed 8 bit data byte; the master then sends a non-acknowledge (nack). finally, the master terminates the transfer with the stop condition [p]. stop separated reads stop separated reads can also be used. this format allows a master to set up the register address pointer for a read and return to that slave at a later time to read the data. in this format the slave address followed by a write command are sent after a start [s] condition. the sc620 then acknowl- edges it is being addressed, and the master responds with the 8-bit register address. the master sends a stop or restart condition and may then address another slave. after per- forming other tasks, the master can send a start or restart condition to the device with a read command. the sc620 acknowledges this request and returns the data from the register location that had previously been set up.
sc620 16 using the i 2 c serial port (continued) i 2 c direct format write slave address register address data swa a ap s ? start condition w ? write = ?0? a ? acknowledge (sent by slave) p ? stop condition slave address ? 7-bit register address ? 8-bit data ? 8-bit i 2 c stop separated format read slave address register address slave address b data nack swa a s/sr ra p p slave address s register address setup access master addresses other slaves register read access s ? start condition w ? write = ?0? r ? read = ?1? a ? acknowledge (sent by slave) nak ? non-acknowledge (sent by master) sr ? repeated start condition p ? stop condition slave address ? 7-bit register address ? 8-bit data ? 8-bit i 2 c combined format read slave address register address slave address data nack s wa a sr r a p s ? start condition w ? write = ?0? r ? read = ?1? a ? acknowledge (sent by slave) nak ? non-acknowledge (sent by master) sr ? repeated start condition p ? stop condition slave address ? 7-bit register address ? 8-bit data ? 8-bit
sc620 17 coplanarity applies to the exposed pad as well as the terminals. 2. controlling dimensions are in millimeters (angles in degrees). 1. inches dimensions nom e bbb aaa a1 a2 d1 e1 dim n l e min d a millimeters max min max nom e b d e/2 e bxn 1 2 n pin 1 indicator (laser mark) a1 c seating plane lxn e/2 d/2 b .007 .009 .012 0.18 0.23 0.30 d1 e1 a2 a .114 .118 3.00 .122 2.90 3.10 notes: bbb c a b aaa c .003 .061 16 .067 .000 .018 - - (.006) 0.08 16 .071 1.55 .024 .002 0.00 0.45 1.80 1.70 0.05 0.60 (0.1524) - - .004 0.10 1.55 2.90 1.70 1.80 3.00 3.10 0.50 bsc .020 bsc 0.30 .012 .020 .016 0.40 0.50 .122 .118 .114 .071 .067 .061 a outline drawing mlpq-ut-16 3x3
semtech corporation power management products division 200 flynn road, camarillo, ca 93012 phone: (805) 498-2111 fax: (805) 498-3804 www.semtech.com contact information sc620 18 land pattern mlpq-ut-20 3x3 c z p y x g h .146 .020 .012 .031 .083 .067 3.70 0.30 0.80 0.50 1.70 2.10 dim (2.90) millimeters dimensions (.114) inches k .067 1.70 failure to do so may compromise the thermal and/or functional performance of the device. shall be connected to a system ground plane. thermal vias in the land pattern of the exposed pad 2. p x h k (c) r r .006 0.15 y g z this land pattern is for reference purposes only. consult your manufacturing group to ensure your company's manufacturing guidelines are met. notes: 1.

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