Datasheet LED Drivers for LCD Backlights White LED Driver for large LCD Panels (DCDC Converter type) BD9428 General Description Features BD9428 is a high efficiency driver for white LEDs and 4ch LED constant current driver and DC/DC converter designed for large LCDs. This IC is built-in a boost Maximum LED Current: 250mA DCDC converters that employ an array of LEDs as the LED Feedback Voltage: 0.40V ( ILED=100mA), light source. BD9428 has some protect function against so lower heat. Adjustable Feed Back Voltage fault conditions, such as the over-voltage protection by following LED Current setting. (OVP), the over current limit protection of DCDC (OCP), 2% LED current accuracy the short circuit protection (SCP), the open detection of (when each LED is set to 100mA) LED string. Therefore BD9428 is available for the LED pin rating 80V fail-safe design over a wide range output voltage. Individual detection and individual LED OFF for both open and short circuits Built-in ISET pin short-circuit protection circuit Key Specifications Set Soft-Start time by external capacitor (SSFB pin). Operating power supply voltage range: 9.0V to 35.0V FETs Gate (N pin) is driven by 10V swing LED minimum current 30mA Built-in Vout overvoltage protection (OVP) / LED maximum current: 250mA Short circuit protection (SCP) Oscillator frequency: 150kHz (RT=100k) DIP16 package Operating Current: 4.5mA (Typ.) Operating temperature range: -40C to +85C Package W(Typ.) x D(Typ.) x H(Max.) DIP16 19.40mm x 6.50mm x 7.95mm Applications TV, Computer Display, Notebook, LCD Backlighting DIP16 Typical Application Circuit (4 light with PWM) VIN Inductor VIN Diode CIN COUT REG100 CREG RN2 FET ON/OFF STB REG100 RVCC N VCC RCS DN RN1 CVCC GND PGND CS LED4 CLED4 RRT RT LED3 AGND ROVP1 CLED3 COVP OVP ROVP2 RFB CFB1 SSFB LED2 CLED2 ISET LED1 RISET CLED1 REG100 FAIL PWM PWM RFAIL Figure 1. Typical Application Circuit Product structureSilicon monolithic integrated circuit This product is not designed protection against radioactive rays . www.rohm.com TSZ02201-0F1F0C100290-1-2 2013 ROHM Co., Ltd. All rights reserved. 1/25 TSZ2211114 001 16.Oct.2013 Rev.001DatasheetDatasheet BD9428 Absolute maximum ratings (Ta=25C) Parameter Symbol Rating Unit Power supply voltage VCC 36 V STB, OVP, PWM, FAIL terminal voltage STB, OVP, PWM, FAIL 36 V LED1 to 4 terminal voltage LED1 to 4 80 V CS, ISET, SSFB, RT terminal voltage CS, N, ISET, SSFB, RT 7 V REG100, N terminal voltage REG100, N 13 V Power dissipation Pd 1.25 *1 W Operating temperature range Topr -40~+85 C Storage temperature range Tstg -55~+150 C Junction temperature Tjmax 150 C *1 Ta = 25C or more, diminished at -10mW/C Operating Ratings (Ta = 25C) Parameter Symbol Limits Unit VCC supply voltage VCC 9.0 to 35.0 V Min. output current of LED1 to 4 ILED MIN 30 mA *1 Max. output current of LED1 to 4 ILED MAX 250 mA *1,2 DC/DC oscillation frequency fsw 100 to 800 kHz Min. on-duty time for PWM light modulation 1 PWM MIN 1 30 us (under soft-start) Min. on-duty time for PWM light modulation 2 PWM MIN 2 5 us (after soft-start) *1 The amount of current per channel. *2 If LED makes significant variations in its reference voltage, the driver will increase power dissipation, resulting in a rise in package temperature. To avoid this problem, design the board with thorough consideration given to heat radiation measures. Pin Configurations Marking Diagram and Physical Dimension (TOP VIEW) (TOP VIEW) FAIL VCC 1 16 2 15 REG100 STB BD9428 3 14 N RT 4 13 GND SSFB LOT No. 5 12 CS ISET 6 11 OVP PWM 7 10 LED1 LED4 8 9 LED2 LED3 Figure 2. Pin Configuration Figure 3. Marking Diagram and Physical Dimension www.rohm.com TSZ02201-0F1F0C100290-1-2 2013 ROHM Co., Ltd. All rights reserved. 2/25 TSZ2211115 001 16.Oct.2013 Rev.001