tm TE CH Preliminary T6316A/B Low-Dropout, Constant-Current White LED Bias Supply FEATURES GENERAL DESCRIPTION • Up to 400mA LED Bias Current • 3% LED Current Matching • Simple LED Brightness Control • Low 0.05uA Shutdown Current • 2.7V to 5V Supply Voltage Range • SOP-8 Package and Lead-free • VSET Resistor Option : T6316A : External Resistor T6316B : 20, 85, 100, 125, 150, 175, 200, 250, 300 and 350mA Output Current Option by Internal Resistor • Build in Thermat Protect 160 °C The T6316A/B low-dropout bias supply for white LEDs is a high-performance alternative to the simple ballast resistors used in conventional white LED designs. The T6316A uses a single resistor to set the bias current for four LEDs, which are matched to 3%. The T6316B build in internal resistor to set the bias current for four LED. The T6316A/B advantages over ballast resistors include significantly better LED to LED bias matching, much lower bias variation with supply voltage variation, significantly lower dropout voltage, and in some applications, significantly improved efficiency. The T6316A/B is available in SOP-8 package and lead-free. Applications PART NUMBER EXAMPLES • Portable Communication Devices • Handheld Electronics • LED/Display Back Light Driver • Lightings PART NO. T6316A-D T6316A-DG PACKAGE SOP-8 SOP-8 lead-free SOP-8 SOP-8 lead-free SOP-8 SOP-8 lead-free Vset Output Current resistor External - External 20mA Internal 20mA Internal 75mA Internal 75mA Internal SOP-8 350mA SOP-8 T6316B-350DG 350mA lead-free Internal T6316B-20D T6316B-20DG T6316B-75D T6316B-75DG T6316B-350D TM Technology Inc. reserves the right P. 1 to change products or specifications without notice. Internal Publication Date: JUN. 2006 Revision: B tm TE CH Preliminary T6316A/B PIN ARRANGEMENT(Top view) LED1 1 8 LED2 2 7 EN LED3 3 6 VDD LED4 4 5 V SS V SET SOP-8 T6316A-D LED1 1 8 EN LED2 2 7 VDD LED3 3 6 V SS LED4 4 5 V SS SOP-8 T6316B-D PIN DESCRIPTION SYMBOL T6316A T6316B LED1 1 1 LED2 2 2 LED3 3 3 LED4 4 4 VSS VDD EN 5 6 7 5,6 7 8 VSET 8 - DESCRIPTION LED 1 Cathode Connection. Current flowing into LED1 is 270/250 times the current flowing into SET. LED1 is high impedance when EN is low. LED 2 Cathode Connection. Current flowing into LED1 is 270/250 times the current flowing into SET. LED2 is high impedance when EN is low. LED 3 Cathode Connection. Current flowing into LED1 is 270/250 times the current flowing into SET. LED3 is high impedance when EN is low. LED 4 Cathode Connection. Current flowing into LED1 is 270/250 times the current flowing into SET. LED4 is high impedance when EN is low. Ground Power supply Enables PN6316A/B signal , H: Ative , L : Power Down . VSET terminal is used to connect an external resistor to set output current. The current flowing into VSET sets the bias current into each LED by ILED_= 250 x ISET. VSET is internally biased to 0.306V. VSET is high impedance when EN is low. TM Technology Inc. reserves the right P. 2 to change products or specifications without notice. Publication Date: JUN. 2006 Revision: B tm TE CH Preliminary T6316A/B ABSOLUTE MAXIMUM RATINGS Parameter Symbol Value Unit Voltage on any pin relative to GND VIN -0.3 to 6 V Operating Temperature Rang TA -40 to +85 °C TLEAD 300 °C TS -65 to +150 °C 1 W Maximum Soldering Temperature (at leads, 10 sec) Storage Temperature Rang Continuous Power Dissipation ( TA = +70°C ) Electrical Characteristics (TA = -40 to 85°C unless otherwise noted. Typical values are at TA =25°C, VEN =3.3V, VLED1 = VLED2= VLED3= VLED4= 1V) Symbol Description Conditions Min. Typ. Max VEN Operating voltage range EN is power supply input 2.7 ISET SET input current range ISETR SET to LED current ratio ILED / ISET, ISET=400uA VSET SET bias voltage ISET=400uA, no loading ICM LED to LED current matching ISET=400uA, 100mA loading ILED Maximum LED sink current Each LED ILSD LED leakage current in shutdown VIH Input high voltage VLED1=VLED2=VLED3=VLED4= 3.3V, EN=GND, TA=+25°C, each LED VEN >VIH for enable, VDD=5V 2.0 VIL Input low voltage VEN <VIL for disable, VDD=5V TTP Thermat Protect 5 1400 1600 TM Technology Inc. reserves the right P. 3 to change products or specifications without notice. T6316A 270 T6316B 250 Unit V uA A/A 0.306 V 3 % 350 400 mA 0.01 1 uA V 0.8 160 V °C Publication Date: JUN. 2006 Revision: B tm TE CH Preliminary T6316A/B Functional Description Applications Information The T6316A/B provides constant current bias supply for white LED designs. The T6316A uses a single resistor to set the bias current for up to four LEDs. LED bias currents are matched to 3%. The T6316B build in internal resistor to set the bias current for four LED. The T6316A/B offers several advantages over using ballast resistors, such as improved LED to LED brightness matching, lower bias variation with supply voltage changes, significantly lower dropout voltage, and in some applications, significantly improved efficiency. Very Low-Cost, High-Efficiency Solution . A battery (single Li+ or three NiMH cells) powers the LEDs directly. This is the least expensive and most efficient architecture. Due to the high forward voltage of white LEDs, the LED brightness may dim slightly at the end of battery life. The T6316A/B current regulating architecture and low dropout greatly minimize this effect compared to using simple ballast resistors. The enable function of the T6316A/B turns on and off the LEDs. Enable Input EN powers the input of the T6316A/B. Drive EN high (> 2.0V) to enable the device; drive EN low (< 0.8V) to disable the device. Driving EN low forces LED1, LED2, LED3, LED4 and SET into a high-impedance state. Setting the Output Current SET controls the LED bias current. Current flowing into LED1, LED2, LED3 and LED4 is 270/250 times greater than the current flowing into SET. Set the output current as follows: T6316A ILED = 270 (0.306V / RSET ) T6316B ILED = 250 (0.306V / RSET ) TM Technology Inc. reserves the right P. 4 to change products or specifications without notice. Publication Date: JUN. 2006 Revision: B tm TE CH Preliminary T6316A/B TYPICAL APPLICATION CIRCUITS V + V D D V D D O N O FF LED 1 LED 2 LED 3 LED 4 EN T6316A SET G N D R V+ VDD ON OFF VDD LED 1 LED 2 LED 3 LED 4 EN T6316B GND Very low-cost, high-efficiency solution TM Technology Inc. reserves the right P. 5 to change products or specifications without notice. Publication Date: JUN. 2006 Revision: B tm TE CH Preliminary T6316A/B PACKAGE DIMENSIONS 8-LEAD SOP B B1 K T h e rm a l P a d * J A1 C1 A C C2 F D Symbol A A1 B B1 C C1 C2 D E F J K H Min. 5.70 3.75 1.35 0.10 0.31 0.30 0.10 Dimension in mm Typ. 6.00 3.95 1.27 1.55 0.41 0.50 0.15 2.23 REF 2.97 REF 0~8° E H Max. 6.30 4.10 5.13 1.80 1.75 0.25 0.51 0.70 0.25 Min. 0.224 0.148 0.052 0.001 0.012 0.012 0.004 Dimension in inch Typ. 0.236 0.156 0.050 0.061 0.016 0.020 0.006 0.088 REF 0.117 REF 0~8° Max. 0.248 0.164 0.202 0.071 0.069 0.004 0.020 0.028 0.010 *Note : The thermal pad on the IC’s bottom has to be mounted on the copper foil. To eliminate the noise influence, the thermal pad is suggested to be connected to GND on PCB. In addition, desired thermal conductivity will be improved, if a heat-conducting copper foil on PCB is soldered with thermal pad. The thermal pad enhances the power dissipation. As a result, a large amount of current can be sunk safely in one package. TM Technology Inc. reserves the right P. 6 to change products or specifications without notice. Publication Date: JUN. 2006 Revision: B