T6311A

tm TE CH Preliminary Product spec. T6311A Low-Dropout, Constant-Current White LED Bias Supply FEATURES • Low 200mV Dropout at 9mA • Up to 150mA LED Bias Current • 0.3% LED Current Matching • Simple LED Brightness Control • Low 40uA Supply Current • Low 0.05uA Shutdown Current • 2.5V to 5.5V Supply Voltage Range • SOP-8 and SOT23-6 Package • Output channel : SOP-8 package for four channel SOT23-6 package for three channel GRNERAL DESCRIPTION The T6311A low-dropout bias supply for white LEDs is a high-performance alternative to the simple ballast resistors used in conventional white LED designs. The T6311A uses a single resistor to set the bias current for four LEDs, which are matched to 0.3%. The T6311A consumes only 40uA of supply current when enabled and 0.05uA when disabled. The T6311A 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 T6311A requires a 200mV dropout at a 9mA load on each output to match the LED brightness. The T6311A is available in SOP-8 and SOT23-6 package. Applications • Cellular Phones • Portable Communication Devices • Handheld Electronics • Digital Cameras • PDAs • LED/Display Back Light Driver • LEDs for Camera Flash PART NUMBER EXAMPLES PART NO. T6311A-D T6311A-X PACKAGE SOP-8 SOT23-6 TM Technology Inc. reserves the right P. 1 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C tm EN GND SET TE CH Preliminary Product spec. T6311A PIN ARRANGEMENT(Top view) SOT23-6 LED1 SOP-8 1 2 3 4 8 7 6 5 EN GND SET NC 1 2 3 6 5 4 LED1 LED2 LED3 LED2 LED3 LED4 PIN DESCRIPTION SYMBO L EN GND SET NC LED4 LED3 LED2 LED1 Pin no. SOP-8 SOT23-6 DESCRIPTION Enable Input/Power Input. Drive high (> 2.5V) to enable; drive low (< 2.2V) to disable. When disabled, SET, LED1, LED2, LED3 and LED4 are high impedance. When enabled, EN is the power input for the T6311A. Ground Bias Current Set Input. The current flowing into SET sets the bias current into each LED by ILED_= 240 x ISET. VSET is internally biased to 1.2V. SET is high impedance when EN is low. No connection. LED 4 Cathode Connection. Current flowing into LED4 is 240 times the current flowing into SET. LED4 is high impedance when EN is low. LED 3 Cathode Connection. Current flowing into LED3 is 240 times the current flowing into SET. LED3 is high impedance when EN is low. LED 2 Cathode Connection. Current flowing into LED2 is 240 times the current flowing into SET. LED2 is high impedance when EN is low. LED 1 Cathode Connection. Current flowing into LED1 is 240 times the current flowing into SET. LED1 is high impedance when EN is low. 8 7 6 5 4 3 2 1 1 2 3 4 5 6 TM Technology Inc. reserves the right P.2 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C tm TE CH Preliminary Product spec. T6311A BLOCK DIAGRAM V+ LED4 ON OFF EN current controller LED3 LED2 LED1 GND REF SET + - RSET VCTRL Fig. 1 TM Technology Inc. reserves the right P.3 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C tm Parameter TE CH Preliminary Product spec. T6311A Symbol VIN TA TLEAD TS Value -0.3 to 6 -40 to +85 300 -65 to +150 1 Unit V °C °C °C W ABSOLUTE MAXIMUM RATINGS Voltage on any pin relative to GND Operating Temperature Rang 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) (Note 1) Symbol VEN ISET VSET Description Operating voltage range SET input current range SET to LED current ratio SET bias voltage SET leakage current in Shutdown Conditions EN is power supply input ILED / ISET, ISET=42uA ISET=42uA EN=GND, VSET=3.3V Each LED ISET=20uA (Note 2) ISET=40uA (Note 3) ISET=80uA (Note 3) TA= -40 to +25°C TA= -40 to +85°C Min. Typ. Max 2.5 5 220 1.08 240 1.2 0.01 0.3 100 100 200 230 0.01 150 180 360 410 1 5.5 260 260 1.32 1 5 Unit V uA A/A V uA uA % mA mV mV mV uA V LED to LED current matching ISET=42uA ILED Maximum LED sink current LED dropout voltage LED leakage current in shutdown VIH VIL IEN Input high voltage Input low voltage EN intput bias current VLED1=VLED2=VLED3=VLED4= 3.3V, EN=GND, TA=+25°C, each LED VEN >VIH for enable 2.5 VEN 2.5V) to enable the device; drive EN low (< 2.2V) to disable the device. When driven high, EN draws 40µA to power the IC. 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 240 times greater than the current flowing into SET. Set the output current as follows: ILED = 240 ( (VCTRL - VSET) / RSET ) where VSET = 1.2V, VCTRL is an external voltage between 1.8V and 5.5V, and RSET is the resistor connected between VCTRL and SET (Fig. 1). TM Technology Inc. reserves the right P.6 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C tm TE CH Preliminary Product spec. T6311A TYPICAL APPLICATION CIRCUITS V+ V E x is tin g LDO CTRL T o o th e r c irc u its SET ON OFF EN GND LED1 LED2 LED3 LED4 Fig. 2 Very low-cost, high-efficiency solution V+ DAC V CTRL SET ON OFF EN LED1 LED2 LED3 LED4 GND Fig. 3 Brightness adjust using DAC TM Technology Inc. reserves the right P.7 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C tm TE CH Preliminary Product spec. T6311A PACKAGE DIMENSIONS 8-LEAD SOP B B1 A1 A C1 C2 C F D H E Symbol A A1 B B1 C C1 C2 D E F 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 0~8° 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 0~8° Max. 0.248 0.164 0.202 0.071 0.069 0.004 0.020 0.028 0.010 TM Technology Inc. reserves the right P.8 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C tm TE CH Preliminary Product spec. T6311A PACKAGE DIMENSIONS SOT23-6 B B1 B2 A1 A C1 C2 C F I D H G E Symbol A A1 B B1 B2 C C1 C2 D E F G H I Min. 2.60 1.40 2.70 0.95 0.90 0 0.30 0.08 Dimension in mm Typ. 2.80 1.575 2.85 1.90(BSC) 0.95(BSC) 1.20 1.10 0.075 0.40 0.45 0.15 0.60(REF) 0~8° 5~15° Max. 3.00 1.60 3.00 Min. 0.102 0.055 0.106 1.45 1.30 0.150 0.60 0.22 0.037 0.035 0 0.012 0.003 Dimension in inch Typ. 0.110 0.062 0.112 0.075(BSC) 0.037(BSC) 0.047 0.043 0.003 0.015 0.018 0.006 0~8° 5~15° Max. 0.118 0.063 0.118 0.057 0.051 0.06 0.023 0.009 TM Technology Inc. reserves the right P.9 to change products or specifications without notice. Publication Date: JUN. 2005 Revision: C