19-3703; Rev 1; 12/10 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog The MAX6979 serial-interfaced LED driver provides 16 open-drain, constant-current-sinking LED driver outputs rated at 5.5V. The MAX6979 operates from a 3V to 5.5V supply. The MAX6979 supply and the LEDs' supply can power up in any order. The constant-current outputs are programmed together to up to 55mA using a single external resistor. The MAX6979 operates with a 25Mb, industry-standard, 4-wire serial interface. The MAX6979 includes circuitry that automatically detects open-circuit LEDs. Fault status is loaded into the serial-interface shift register when LE goes high and is automatically shifted out on DOUT when the next data transmission is shifted in. The MAX6979 includes a fail-safe feature for safetyrelated applications, which blanks the display if the serial interface fails. If the serial interface becomes inactive for more than 1s, all driver output latches are automatically cleared. This turns off all LEDs connected to the outputs. The shift register data is not disturbed. The outputs remain off until the driver output latches are updated with data turning them on, so recovery is automatic if the transmission failure is temporary. The watchdog function requires no software change to the application driving the MAX6979. The MAX6979 uses the industry-standard shift-registerplus-latch-type serial interface. The driver accepts data shifted into a 16-bit shift register using data input DIN and clock input CLK. Input data appears at the output DOUT 16 clock cycles later to allow cascading of multiple MAX6979s. The latch-enable input, LE, loads the 16 bits of shift-register data into a 16-bit output latch to set which LEDs are on and which are off. The outputenable input, OE, gates all 16 outputs on and off, and is fast enough to be used as a PWM input for LED intensity control. The MAX6979 is one of a family of 12 shift-register-pluslatch-type LED drivers. The family includes 8-port and 16-port types, with 5.5V- or 36V-rated LED outputs, with and without open-circuit LED detection and watchdog. All versions operate from a 3V to 5.5V supply, and are specified over the -40C to +125C temperature range. Applications Variable Message Signs Marquee Displays Point-of-Order Signs Traffic Signs Gaming Features Architectural Lighting Features o o o o o o o o o o o 25Mb Industry-Standard, 4-Wire Serial Interface at 5V 3V to 5.5V Logic Supply 16 Constant-Current LED Outputs Rated at 5.5V Up to 55mA Continuous Current per Output Output Current Programmed by Single Resistor 3% Current Matching Between Outputs 6% Current Matching Between ICs Watchdog Clears Display if Interface Fails Reports Open-Circuit LED Faults High-Dissipation, 24-Pin Packages -40C to +125C Temperature Range Ordering Information PART TEMP RANGE PIN-PACKAGE -40C to +125C 24 TSSOP MAX6979AUG+ MAX6979APG+ -40C to +125C 24 PDIP +Denotes a lead(Pb)-free/RoHS-compliant package. Typical Application Circuit and Selector Guide appear at end of data sheet. Pin Configuration TOP VIEW GND 1 + 24 V+ DIN 2 23 SET CLK 3 22 DOUT 21 OE LE 4 20 OUT15 OUT0 5 19 OUT14 OUT1 6 OUT2 7 MAX6979AUG MAX6979APG 18 OUT13 OUT3 8 17 OUT12 OUT4 9 16 OUT11 OUT5 10 15 OUT10 OUT6 11 14 OUT9 OUT7 12 13 OUT8 TSSOP/PDIP ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX6979 General Description MAX6979 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog ABSOLUTE MAXIMUM RATINGS Voltage (with respect to GND) V+ .............................................................................-0.3V to +6V OUT_ ........................................................................-0.3V to +6V DIN, CLK, LE, OE, SE ..................................-0.3V to (V+ + 0.3V) DOUT_ Current .................................................................10mA OUT_ Sink Current ..............................................................60mA Total GND Current ............................................................960mA Continuous Power Dissipation (TA = +70C) 24-Pin PDIP (derate 13.3mW/C over +70C)............1067mW 24-Pin TSSOP (derate 12.2mW/C over +70C) .........975mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Soldering Temperature (reflow) Lead(Pb)-free packages..............................................+260C Packages containing lead(Pb).....................................+240C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (Typical Operating Circuit, V+ = 3V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at V+ = 5V, TA = +25C.) (Note 1) PARAMETER Operating Supply Voltage Output Voltage SYMBOL CONDITIONS V+ MIN TYP MAX UNITS 5.5 V 5.5 V 5.7 8 mA 3.0 VOUT Standby Current (Interface Idle, All Output Ports High Impedance, RSET = 360) I+ All logic inputs at V+ or GND, DOUT unloaded Standby Current (Interface Running, All Output Ports High Impedance, RSET = 360) I+ fCLK = 5MHz, OE = V+, DIN and LE = V+ or GND, DOUT unloaded 6 8.5 mA Supply Current (Interface Idle, All Output Ports Active Low, RSET = 360) I+ All logic inputs at V+ or GND, DOUT unloaded 18 25 mA Input High Voltage DIN, CLK, LE, OE VIH Input Low Voltage DIN, CLK, LE, OE VIL Hysteresis Voltage DIN, CLK, LE, OE VI Input Leakage Current DIN, CLK, LE, OE 0.7 x V+ 0.3 x V+ 0.8 IIH, IIL -1 Output High Voltage DOUT VOH ISOURCE = 4mA Output Low Voltage VOL ISINK = 4mA Output Current OUT IOUT V+ = 3V to 5.5V, VOUT = 0.5V to 2.5V, RSET = 360 Output Leakage Current OUT ILEAK OE = V+, VOUT = V+ Watchdog Timeout 2 tWD V V V +1 V+ - 0.5V A V 0.5 V 37 50 61 mA 1 A 0.1 1 2.5 s _______________________________________________________________________________________ 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog (Typical Operating Circuit, V+ = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1 and 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CLK Clock Period tCP 40 ns CLK Pulse-Width High tCH 19 ns CLK Pulse-Width Low tCL 19 ns DIN Setup Time tDS 4 ns DIN Hold Time tDH 8 DOUT Propagation Delay tDO 12 DOUT Rise and Fall Time tDR, tDF LE Setup Time CDOUT = 10pF, 20% to 80% tLS ns 32 ns 10 ns 10 ns LE Rising to OUT Rising Delay tLRR (Note 2) 100 ns LE Rising to OUT Falling Delay tLRF (Note 2) 300 ns CLK Rising to OUT Rising Delay tCRR (Note 2) 100 ns CLK Rising to OUT Falling Delay tCRF (Note 2) 310 ns OE Rising to OUT Rising Delay tOEH 100 ns OE Falling to OUT Falling Delay tOEL 320 ns LED Output OUT Turn-On Fall Time tf 80% to 20%; pullup resistor = 65 120 ns LED Output OUT Turn-Off Rise Time tr 20% to 80%; pullup resistor = 65 120 ns _______________________________________________________________________________________ 3 MAX6979 5V TIMING CHARACTERISTICS 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog MAX6979 3.3V TIMING CHARACTERISTICS (Typical Operating Circuit, V+ = 3V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1 and 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CLK Clock Period tCP 52 ns CLK Pulse-Width High tCH 24 ns CLK Pulse-Width Low tCL 24 ns DIN Setup Time tDS 4 ns DIN Hold Time tDH 8 DOUT Propagation Delay tDO 12 DOUT Rise and Fall Time ns CDOUT = 10pF, 20% to 80% LE Setup Time tLS 50 ns 12 ns 15 ns LE Rising to OUT Rising Delay 120 ns LE Rising to OUT Falling Delay 310 ns CLK Rising to OUT Rising Delay 120 ns CLK Rising to OUT Falling Delay 330 ns OE Rising to OUT Rising Delay tOEH 120 ns OE Falling to OUT Falling Delay tOEL 330 ns LED Output OUT Turn-On Fall Time tf 80% to 20% 120 ns LED Output OUT Turn-Off Rise Time tr 20% to 80% 120 ns Note 1: All parameters tested at TA = +25C. Specifications overtemperature are guaranteed by design. Note 2: See Figure 3. Typical Operating Characteristics (TA = +25C, unless otherwise noted.) 3.75 3.50 3.25 3.00 TA = +25C TA = -40C 5.4 5.2 5.0 4.8 4.6 TA = -40C TA = +25C 2.50 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 MAX6979 toc03 16 14 12 TA = +25C 10 TA = -40C 6 4.0 3.5 TA = +85C 8 4.2 3.0 TA = +125C 18 4.4 2.75 4 TA = +85C SUPPLY CURRENT (mA) TA = +85C 4.00 TA = +125C 5.6 20 MAX6979 toc02 TA = +125C 5.8 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 4.25 6.0 MAX6979 toc01 4.50 SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS ON, RSET = 720) SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 360) SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 720) 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.0 5.5 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE (RSET = 720, V+ = 3.3V) 16 TA = +25C 14 TA = -40C 20 TA = +85C 15 TA = +125C 10 5 12 0 3.0 3.5 4.0 4.5 5.0 50 TA = -40C 40 TA = +25C TA = +85C 30 TA = +125C 20 10 TA = -40C 10 0 0 5.5 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 SUPPLY VOLTAGE (V) PORT OUTPUT VOLTAGE (V) PORT OUTPUT VOLTAGE (V) PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE (RSET = 720, V+ = 5.0V) PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE (RSET = 360, V+ = 5.0V) PORT OUTPUT CURRENT vs. SUPPLY VOLTAGE (RSET = 720, VOUT = 2V) TA = -40C 20 TA = +25C TA = +85C 15 TA = +125C 10 5 50 PORT OUTPUT CURRENT (mA) PORT OUTPUT CURRENT (mA) 25 27.0 MAX6979 toc08 60 MAX6979 toc07 30 TA = -40C 40 TA = +25C TA = +85C 30 TA = +125C 20 10 0 1.0 1.5 2.0 2.5 3.0 0.5 PORT OUTPUT VOLTAGE (V) 1.0 1.5 2.0 2.5 26.0 25.5 TA = +85C 3.5 3.0 PORT OUTPUT VOLTAGE (V) 53 TA = -40C 4.5 5.0 5.5 PORT OUTPUT CURRENT vs. RSET RESISTANCE (V+ = 5.0V) TA = +25C 52 51 TA = +125C 4.0 SUPPLY VOLTAGE (V) TA = +85C 49 50 MAX6979 toc11 54 TA = +125C 25.0 3.0 PORT OUTPUT CURRENT vs. SUPPLY VOLTAGE (RSET = 360, VOUT = 2V) 50 TA = -40C 24.0 0 MAX6979 toc10 0.5 TA = +25C 26.5 24.5 0 0 PORT OUTPUT CURRENT (mA) PORT OUTPUT CURRENT (mA) TA = +25C MAX6979 toc06 25 MAX6979 toc09 18 60 MAX6979 toc05 30 PORT OUTPUT CURRENT (mA) SUPPLY CURRENT (mA) 20 TA = +85C PORT OUTPUT CURRENT (mA) TA = +125C MAX6979 toc04 22 PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE (RSET = 360, V+ = 3.3V) PORT OUTPUT CURRENT (mA) SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS ON, RSET = 360) 40 30 20 10 0 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 0 300 600 900 1200 1500 RSET RESISTANCE () _______________________________________________________________________________________ 5 MAX6979 Typical Operating Characteristics (continued) (TA = +25C, unless otherwise noted.) 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog MAX6979 Pin Description PIN NAME FUNCTION 1 GND Ground 2 DIN Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK's rising edge. 3 CLK Serial-Clock Input. Data is loaded into the internal 16-bit shift register on CLK's rising edge. 4 LE 5-20 OUT0- OUT15 21 OE 22 DOUT 23 SET LED Current Setting. Connect SET to GND through a resistor (RSET) to set the maximum LED current. 24 V+ Positive Supply Voltage. Bypass V+ to GND with a 0.1F ceramic capacitor. Load-Enable Input. Data is loaded transparently from the internal shift register(s) to the output latch(es) while LE is high. Data is latched into the output latch(es) on LE's falling edge, and retained while LE is low. LED Driver Outputs. OUT0 to OUT15 are open-drain, constant-current-sinking outputs rated to 5.5V. Output Enable Input. High forces outputs OUT0 to OUT15 high impedance without altering the contents of the output latches. Low enables outputs OUT0 to OUT15 to follow the state of the output latches. Serial-Data Output. Data is clocked out of the 16-bit internal shift register to DOUT on CLK's rising edge. CLK MAX6979 DIN D0 SERIAL-TO-PARALLEL SHIFT REGISTER D15 LE D0 LATCHES D15 DOUT POWER-ON RESET V+ WATCHDOG OE V+ CONSTANT-CURRENT SINKS D0 D15 CURRENT REFERENCE FAULT DETECTION OUT0 OUT2 RSET GND OUT15 OUT13 OUT1 OUT14 GND Figure 1. MAX6979 Block Diagram Detailed Description The MAX6979 LED driver comprises a 4-wire serial interface driving eight constant-current sinking opendrain output ports. The outputs drive LEDs in either static or multiplex applications (Figure 1). The constantcurrent outputs are guaranteed for current accuracy 6 not only with chip-supply voltage variations (5V 10% and 3V to 5.5V), but also over a realistic range of driver output voltage drop (0.5V to 2.5V). The drivers use current-sensing feedback circuitry (not simple current mirrors) to ensure very small current variations over the full allowed range of output voltage (see the Typical Operating Characteristics). _______________________________________________________________________________________ 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog tCL tCH tLS tCP MAX6979 LE tLW tLF CLK tDH tDS DIN D15 D14 D1 D0 tDO D15 DOUT tOEW OE tOEL tOEH . 80% OUT_ 20% tf tr Figure 2. 4-Wire Serial-Interface Timing Diagram The 4-wire serial interface comprises a 16-bit shift register and a 16-bit transparent latch. The shift register is written through a clock input CLK and a data input DIN and the data propagates to a data output DOUT. The data output allows multiple drivers to be cascaded and operated together. The contents of the 16-bit shift register are loaded into the transparent latch through a latch-enable input LE. The latch is transparent to the shift register outputs when high, and latches the current state on the falling edge of LE. Each driver output is an open-drain, constant-current sink that should be connected to the cathode of either a single LED or a series string of multiple LEDs. The LED anode can be connected to a supply voltage of up to 5.5V, independent of the MAX6979 supply, V+. The constant-current capability is up to 55mA per output, set for all 16 outputs by an external resistor, RSET. 4-Wire Serial Interface The serial interface on the MAX6979 is a 4-wire serial interface using four inputs (DIN, CLK, LE, OE) and a data output (DOUT). This interface is used to write display data to the MAX6979. The serial-interface data word length is 16 bits, D0-D15. See Figure 2. The functions of the five interface pins are as follows. DIN is the serial-data input, and must be stable when it is sampled on the rising edge of CLK. Data is shifted in, MSB first. This means that data bit D15 is clocked in first, followed by 15 more data bits, finishing with the LSB D0. CLK is the serial-clock input, which shifts data at DIN into the MAX6979 16-bit shift register on its rising edge. LE is the latch load input of the MAX6979, which transfers data from the MAX6979 16-bit shift register to its 16bit latch when LE is high (transparent latch), and latches the data on the falling edge of LE (Figure 2). The fourth input provides output-enable control of the output drivers. OE is high to force outputs OUT0-OUT15 high impedance, without altering the contents of the output latches, and low to enable outputs OUT0-OUT15 to follow the state of the output latches. OE is independent of the operation of the serial interface. Data can be shifted into the serial-interface shift register and latched regardless of the state of OE. DOUT is the serial-data output, which shifts data out from the MAX6979's 16-bit shift register on the rising edge of CLK. Data at DIN is propagated through the shift register and appears at DOUT 16 clock cycles later. See Figure 2. _______________________________________________________________________________________ 7 MAX6979 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog OE LE tLRF OUT_ LE CLK DOUT D14 D13 D15 D12 LE tLRR FAULT STATUS BITS OUT_ Figure 4. Fault Timing Diagram CLK tCRF OUT_ CLK tCRR OUT_ Figure 3. LE and CLK to OUT_ Timing Watchdog The MAX6979 includes a watchdog circuit that monitors the CLK, DIN, and LE inputs. If there is no transition on all of these inputs for nominally 1s, then the output latches are cleared and outputs OUT0-OUT15 go high impedance like the initial power-up condition. This turns off all LEDs connected to the outputs. The shift-register data does not change, just the output-latch data. The watchdog is intended to be used as a fail-safe feature for applications, which prefer a blank display to an incorrect display if the serial interface fails. When the watchdog triggers, the outputs remain off until the driver output latches are updated with data turning them on. Recovery is therefore automatic if the transmission failure is temporary, because the MAX6979 does not lock up in the watchdog timeout state. The MAX6979 operates correctly when the serial interface is next activated, and the watchdog circuit is reset and starts monitoring the serial interface again. The watchdog function requires no software change to the application driving the MAX6979. LED Fault Detection The MAX6979 includes circuitry that detects open-circuit LEDs automatically. An open-circuit fault occurs when an output is programmed to sink current but less than about 50% of the programmed current flows. Open circuits are checked just after the falling edge of 8 OE. The fault data is latched on the rising edge of LE and is shifted out when new LED data is loaded into the output latches from the shift register. If one or more output ports are detected with an open-circuit fault, the D14 and D13 bits of DOUT go high. If no open-circuit faults are detected, the D14 and D13 are set to low. The data in the other 14 bit positions in DOUT are not altered. Fault status is shifted out on DOUT when the next data transmission is shifted in after the rising edge of LE. LE is normally taken high after all 16 bits of new LED data have been clocked into the shift register(s), and then DOUT outputs data bit D15. On the next two rising edges of CLK, the 2 fault status bits, D14 and D13, are clocked out in that order, followed by the remaining 13 unchanged data bits D12 to D0. A typical fault-detecting application tests all the-shifted out data. Bits D0-D12 and D15 are checked against the originally transmitted data to check data-link integrity. Bits D13 and D14 are checked first to see that they contain the same data (validating the status) and second, whether faults are reported or not by the actual logic level. Figure 4 is the LE and CLK to OUT_ timing diagram. Applications Information Selecting External Component RSET to Set LED Output Current The MAX6979 uses an external resistor RSET to set the LED current for outputs OUT0-OUT15. The minimum allowed value of RSET is 327.3, which sets the output currents to 55mA. The maximum allowed value of RSET is 1.5k. The reference value, 360, sets the output currents to 50mA. To set a different output current, use the formula: RSET = 18,000/IOUT where IOUT is the desired output current in mA. _______________________________________________________________________________________ 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog SERIAL CLOCK DATA INPUT INPUT CLK D0 DIN SHIFT-REGISTER CONTENTS D1 D2 LOAD INPUT LE ... Dn-1 Dn LATCH CONTENTS D0 D1 D2 OUTPUT CONTENTS BLANKING INPUT OE D0 D1 D2 ... Dn-1 Dn ... Dn-1 Dn H H R1 R2 ... Rn-2 Rn-1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- L L R1 R2 ... Rn-2 Rn-1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- X -- R0 R1 R2 ... Rn-1 Rn -- -- -- -- -- -- -- -- -- -- X X X ... X H R0 R1 R2 -- Rn-1 Rn -- -- -- -- -- -- -- -- -- P1 P2 P3 L P0 P1 P2 ... Pn-1 Pn L P0 P1 P2 -- -- -- -- -- ... Pn-1 Pn -- -- -- -- X X X ... H X X X ... Pn-1 Pn Hi-Z Hi-Z Hi-Z ... Hi-Z Hi-Z L = Low-logic level; H = High-logic level; X = Don't care; P = Present state; R = Previous state Computing Power Dissipation Overtemperature Cutoff The upper limit for power dissipation (P D ) for the MAX6979 is determined from the following equation: PD = (V+ x I+) + (VOUT x DUTY x IOUT x N) where: The MAX6979 contains an internal temperature sensor that turns off all outputs when the die temperature exceeds approximately +165C. The outputs are enabled again when the die temperature drops below approximately +140C. Register contents are not affected, so when a driver is overdissipating, the external symptom is the load LEDs cycling between on and off as the driver repeatedly overheats and cools, alternately turning the LEDs off and then back on again. V+ = supply voltage I+ = operating supply current when sinking IOUT LED drive current into N outputs DUTY = PWM duty cycle applied to OE N = number of MAX6979 outputs driving LEDs at the same time (maximum is 16) VOUT = MAX6979 port output voltage when driving load LED(s) IOUT = LED drive current programmed by RSET PD = power dissipation, in mW if currents are in mA Dissipation example: IOUT = 47mA, N = 16, DUTY = 1, VOUT = 2V, V+ = 5.25V PD = (5.25V x 25mA) + (2V x 1 x 47mA x 16) = 1.776W Thus, for a 24-pin TSSOP package (TJA = 1/0.0122 = +82C/W from the Absolute Maximum Ratings ), the maximum allowed ambient temperature TA is given by: TJ(MAX) = TA + (PD x TJA) = +150C = TA + (1.776 x 82C/W) so TA = +145.6C. Power-Supply Considerations The MAX6979 operates with a chip supply V+, and one or more LED supplies. Bypass each supply to GND with a 0.1F capacitor as close to the MAX6979 as possible. This is normally adequate for static LED driving. For multiplex or PWM applications, it is necessary to add an additional bulk electrolytic capacitor of 4.7F or more to each supply for every 4 to 16 MAX6979s. The necessary capacitance depends on the LED load current, PWM switching frequency, and serial interface speed. Inadequate V+ decoupling can cause timing problems, and very noisy LED supplies can affect LED current regulation. _______________________________________________________________________________________ 9 MAX6979 Table 1. 4-Wire Serial-Interface Truth Table 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog MAX6979 Selector Guide PART NO. OF OUTPUTS MAX OUTPUT VOLTAGE (V) 8 5.5 MAX OUTPUT CURRENT MAX6968 LED FAULT DETECTION WATCHDOG -- -- Yes -- MAX6978 Yes Yes MAX6970 -- -- Yes -- Yes Yes -- -- Yes -- MAX6979 Yes Yes MAX6971 -- -- MAX6977 8 MAX6981 36 MAX6980 55mA MAX6969 16 MAX6984 16 MAX6982 5.5 36 MAX6983 Yes -- Yes Yes Typical Application Circuit 28V +5V C V+ SCLK CLK MOSI DIN MISO DOUT LOAD LATCH ENABLE OE 360 SET GND MAX6979 OUT0 OUT1 OUT2 OUT3 OUT4 OUT5 OUT6 OUT7 OUT8 OUT9 OUT10 OUT11 OUT12 OUT13 OUT14 OUT15 0V 10 ______________________________________________________________________________________ 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog PROCESS: BiCMOS For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 24 PDIP N24+1 21-0043 -- 24 TSSOP U24+1 21-0066 90-0118 ______________________________________________________________________________________ 11 MAX6979 Package Information Chip Information MAX6979 16-Port, 5.5V Constant-Current LED Driver with LED Fault Detection and Watchdog Revision History REVISION NUMBER REVISION DATE 0 5/05 Initial release 1 12/10 Updated Ordering Information and Watchdog section DESCRIPTION PAGES CHANGED -- 1, 8 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.