MAX6968 19-3555 Rev 2 7/05 8-Port, 5.5V Constant-Current LED Driver General Description Features The MAX6968 serial-interfaced LED driver provides 25Mb Industry-Standard 4-Wire Serial Interface at 5V eight open-drain, constant-current sinking LED driver 3V to 5.5V Logic Supply outputs rated at 5.5V. The MAX6968 operates from a 3V to 5.5V supply. The MAX6968 supply and the LEDs 8 Constant-Current LED Outputs Rated at 5.5V supply or supplies may power up in any order. The Up to 55mA Continuous Current per Output constant-current outputs are programmed together to up to 55mA using a single external resistor. The Output Current Programmed by Single Resistor MAX6968 operates with a 25Mb, industry-standard, 4- 3% Current Matching Between Outputs wire serial interface. The MAX6968 uses the industry-standard shift-register- 6% Current Matching Between ICs plus-latch-type serial interface. The driver accepts data -40C to +125C Temperature Range shifted into an 8-bit shift register using data input DIN and clock input CLK. Input data appears at the output DOUT eight clock cycles later to allow cascading of multiple MAX6968s. The latch-enable input LE loads the 8 bits of shift register data into an 8-bit output latch to set which LEDs are on and which are off. The output- enable input OE gates all eight outputs on and off, and Ordering Information is fast enough to be used as a PWM input for LED PART TEMP RANGE PIN-PACKAGE intensity control. MAX6968AUE -40C to +125C 16 TSSOP-EP* For applications requiring LED fault detection, refer to MAX6968APE -40C to +125C 16 PDIP the MAX6977 data sheet that automatically detects open-circuit LEDs. MAX6968AAE -40C to +125C 16 SSOP For safety-related applications requiring a watchdog *EP = Exposed pad. timer, refer to the MAX6978 data sheet that includes a fail-safe feature that blanks the display if the serial inter- face becomes inactive for more than 1s. Typical Application Circuit and Selector Guide appear at The MAX6968 is one of a family of 12 shift-register-plus- end of data sheet. latch-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. Pin Configuration All versions operate from a 3V to 5.5V supply, and are specified over the -40C to +125C temperature range. TOP VIEW Applications GND 1 16 V+ Variable Message Signs DIN 2 15 SET Marquee Displays CLK 3 14 DOUT Point-of-Order Signs LE 4 MAX6968AUE 13 OE MAX6968APE Traffic Signs OUT0 5 12 OUT7 MAX6968AAE OUT1 6 11 OUT6 Gaming Features OUT2 7 10 OUT5 Architectural Lighting OUT3 8 9 OUT4 TSSOP/PDIP/SSOP Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.8-Port, 5.5V Constant-Current LED Driver ABSOLUTE MAXIMUM RATINGS Voltage (with respect to GND) Continuous Power Dissipation (T = +70C) A V+ ............................................................................-0.3V to +6V 16-Pin SSOP (derate 7.1mW/C above +70C) ............571mW OUT .......................................................................-0.3V to +6V 16-Pin PDIP (derate 10.5mW/C above +70C)............842mW DIN, CLK, LE, OE, SET ................................-0.3V to (V+ + 0.3V) 16-Pin TSSOP (derate 21.3mW/C over DOUT Current ..................................................................10mA T = +70C) ..............................................................1702mW A OUT Sink Current .............................................................60mA Operating Temperature Range .........................-40C to +125C Total GND Current ...........................................................480mA Junction Temperature......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C 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, T = T to T , unless otherwise noted. Typical values are at V+ = 5V, T = +25C.) A MIN MAX A (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Operating Supply Voltage V+ 3.0 5.5 V Output Voltage V 5.5 V OUT Standby Current All logic inputs at V+ or GND, DOUT (Interface Idle, All Output Ports I 4.5 5.6 mA + unloaded High Impedance, R = 360 ) SET Standby Current (Interface Running, All Output f = 5MHz, OE = V+, DIN and LE = V+ CLK I 4.7 6 mA + Ports High Impedance, or GND, DOUT unloaded R = 360 ) SET Supply Current All logic inputs at V+ or GND, (Interface Idle, All Output Ports I 10 25 mA + DOUT unloaded Active Low, R = 360 ) SET Input High Voltage V 0.7 V+ V IH DIN, CLK, LE, OE Input Low Voltage V 0.3 V+ V IL DIN, CLK, LE, OE Hysteresis Voltage V 0.8 V I DIN, CLK, LE, OE Input Leakage Current I , I -1 +1 A IH IL DIN, CLK, LE, OE V + Output High-Voltage DOUT V I = 4mA V OH SOURCE - 0.5V Output Low Voltage V I = 4mA 0.5 V OL SINK V+ = 3V to 5.5V, V = 0.5V to 2.5V, OUT Output Current OUT I 42 50 56 mA OUT R = 360 SET Output Leakage Current OUT I OE = V+, V = V+ 1 A LEAK OUT Watchdog Timeout t 1s WD 2 MAX6968