tm TE CH Preliminary T6326A Low-Dropout, Constant-Current White LED with Channel Control FEATURES GRNERAL DESCRIPTION • Up to 400mA LED Bias Current • 3% LED Current Matching • Simple LED Brightness Control • Low 0.05uA Shutdown Current • 3V to 5.5V Supply Voltage Range • MSOP-10L Package • Output channel : MSOP-10L package for four channel • LED1~4 Channels ON / OFF states: T6326A-AM with 16 channel states T6326A-BM with 5 channel states • Build in Thermal Protect 140 °C The T6326A low-dropout bias supply for white LEDs is a high-performance alternative to the simple ballast resistors used in conventional white LED designs. The T6326A with internal channel on/off select function. The T6326A uses a single resistor to set the bias current for four LEDs, which are matched to 3%. The T6326A 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 T6326A is available in MSOP-10L 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. PACKAGE ON states T6326A-AM MSOP-10L 16 T6326A-BM MSOP-10L 5 TM Technology Inc. reserves the right P. 1 to change products or specifications without notice. Publication Date: FEB. 2006 Revision: A tm TE CH Preliminary T6326A PIN ARRANGEMENT(Top view) VSET 1 10 CH SW LED1 2 9 EN LED2 3 8 VDD LED3 4 7 VSS LED4 5 6 VSS MSOP-10L PIN DESCRIPTION SYMBOL MSOP -10L VSET 1 LED1 2 LED2 3 LED3 4 LED4 5 VSS VDD EN CHSW 6,7 8 9 10 DESCRIPTION VSET terminal is used to connect an extermal 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. LED 1 Cathode Connection. Current flowing into LED1 is 250 times the current flowing into SET. LED1 is high impedance when EN is low. LED 2 Cathode Connection. Current flowing into LED1 is 250 times the current flowing into SET. LED2 is high impedance when EN is low. LED 3 Cathode Connection. Current flowing into LED1 is 250 times the current flowing into SET. LED3 is high impedance when EN is low. LED 4 Cathode Connection. Current flowing into LED1 is 250 times the current flowing into SET. LED4 is high impedance when EN is low. Ground Power supply Enables T6326A signal, H: Ative, L : Power Down . Set LED1~4 Channels ON / OFF, the rising edge of CHSW will change next states. TM Technology Inc. reserves the right P.2 to change products or specifications without notice. Publication Date: FEB. 2006 Revision: A tm TE CH Preliminary T6326A 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 EN is power supply input Min. Typ. Max VEN Operating voltage range ISET SET input current range ISETR SET to LED current ratio ILED / ISET, ISET=400uA VSET SET bias voltage ISET=400uA ICM LED to LED current matching ISET=400uA 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 2.5 VIL Input low voltage VEN <VIL for disable, VDD=5V TTP Thermat Protect TM Technology Inc. reserves the right P.3 to change products or specifications without notice. 3 5.5 Unit V 1400 1600 uA 250 A/A 0.306 V 3 % 350 400 mA 0.01 1 uA V 2.2 140 V °C Publication Date: FEB. 2006 Revision: A tm TE CH Preliminary T6326A Functional Description Applications Information The T6326A provides constant current bias supply for white LED designs. The T6326A uses a single resistor to set the bias current for up to three LEDs. LED bias currents are matched to 3% by the T6326A current matching architecture (Fig. 1). The T6326A 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 T6326A current regulating architecture and low dropout greatly minimize this effect compared to using simple ballast resistors. The enable function of the T6326A turns on and off the LEDs. Enable Input EN powers the input of the T6326A. Drive EN high (> 2.5V) to enable the device; drive EN low (< 2.2V) to disable the device. Driving EN low forces LED1, LED2, LED3, LED4 and SET into a high-impedance state. CHSW Input The Set LED1~4 Channels ON / OFF , the rising edge of CHSW will change next states. The T6326A with Internal SEL pad Channel function select. The T6326A-AM with 16 channel states: LED[1:4]=[1111],[1110],[1101],[1100], [1011],[1010],[1001],[1000], [0111],[0110],[0101],[0100], [0011],[0010],[0001],[0000] The T6326A-BM with 5 channel states : LED[1:4]=[1111],[1110],[1100],[1000],[0000] Setting the Output Current SET controls the LED bias current. Current flowing into LED1, LED2, LED3 and LED4 is 250 times greater than the current flowing into SET. Set the output current as follows: ILED = 250 (VSET / RSET ) VSET = 0.306V TM Technology Inc. reserves the right P.4 to change products or specifications without notice. Publication Date: FEB. 2006 Revision: A tm TE CH Preliminary T6326A TYPICAL APPLICATION CIRCUITS V+ VDD VDD ON OFF LED1 LED2 LED3 LED4 EN CHSW SET GND R Very low-cost, high-efficiency solution TM Technology Inc. reserves the right P.5 to change products or specifications without notice. Publication Date: FEB. 2006 Revision: A tm TE CH Preliminary T6326A PACKAGE DIMENSIONS 10-LEAD MSOP-10L B B1 K T h e rm a l P a d * A1 J C1 A C C2 F D Symbol A A1 B B1 C C1 C2 D E F J K H Min. 0.75 0.00 0.17 0.40 0.10 - Dimension in mm Typ. 4.90 3.00 3.00 0.50 0.85 0.60 0.15 1.715 REF 1.600 REF 0~8° E H Max. 1.10 0.95 0.15 0.27 0.80 0.25 - Min. 0.029 0.000 0.007 0.015 0.004 - Dimension in inch Typ. 0.193 0.118 0.118 0.019 0.033 0.024 0.006 0.067 REF 0.063 REF 0~8° Max. 0.043 0.037 0.006 0.010 0.031 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: FEB. 2006 Revision: A