IS32BL3552 BOOST TYPE LED DRIVER WITH 2-CHANNEL CURRENT SOURCE QUICK START DESCRIPTION The IS32BL3552 is a white LED driver for backlight applications based on a highly efficient boost controller operating over a wide input voltage range of 4.5V to 33V. The IS32BL3552 contains two regulated current sources with 1.5% (Typ.) current matching between strings for a uniform LED brightness. Each current source can be programmed via an external resistor to drive from 40mA to 360mA. A fast slew rate current source allows high frequency and narrow pulse width dimming signals to achieve a very high contrast ratio. The device operating frequency can be adjusted from 0.1MHz to 1MHz. The IS32BL3552 has safety protection features to prevent damage during fault conditions. Protection features include an internal soft-start circuit to prevent a high inrush current during start up, open/short LED protection to automatically disable a faulty current source, over temperature protection (OTP), cycle-by-cycle current limit, under voltage lockout (UVLO), programmable OVP, VOUT short / Schottky diode open protection and Schottky Diode short-circuit protection. RECOMMENDED EQUIPMENT Input voltage range: 4.5V to 33V 2-Channel LED current sinks, 360mA per string LED current adjustable from 40mA to 360mA String-to-string current matching accuracy: 1.5% Adjustable operating frequency: 100kHz to 1MHz External PWM dimming High contrast ratio Less than 3µA shutdown current Programmable soft-start Built-in protection features - OCP, OTP, UVLO - Open/short LED protection - Programmable OVP - Schottky Diode/inductor short-circuit protection Automotive AEC-Q100 qualified 12V, 3A power supply LED load board Excel Calculator download from the ISSI website www.issi.com/US/product-analog-backlight-driver.shtml ABSOLUTE MAXIMUM RATINGS FEATURES Figure 1: Photo of IS32BL3552 Evaluation Board ≤ 33V power supply All LED channels must be connected to an LED load. Caution: Do not exceed the conditions listed above, otherwise the board will be damaged. PROCEDURE The IS32BL3552 evaluation board is fully assembled and tested. Follow the steps listed below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. 1) 2) Connect the ground terminal of the power supply to the GND and the positive terminal to the VCC. Or connect the DC power to the connector (DC IN). Turn on the power supply and pay attention to the supply current. If the current exceeds 2A, please check for circuit fault. ORDERING INFORMATION Part No. Temperature Range Package IS32BL3552-ZLA3-EB -40°C ~ +125°C (Automotive) eTSSOP-16, Lead-free Table 1: Ordering Information For pricing, delivery, and ordering information, please contacts ISSI’s analog marketing team at [email protected] or (408) 969-6600. Integrated Silicon Solution, Inc. – www.issi.com Rev. C, 07/24/2015 1 IS32BL3552 BOOST TYPE LED DRIVER WITH 2-CHANNEL CURRENT SOURCE 2. W2 Overvoltage Protection – VOVP can be adjusted from 10.6V to 50V by W2. VOVP should be set to 1.2 times VOUT to ensure OVP function. The IS32BL3552 operation is unstable if VOVP is set to less than VOUT. EVALUATION BOARD OPERATION IS32BL3552 evaluation board drives two strings of WLEDs. There are three variable resistors used for adjusting the operating frequency (W1), OVP voltage (W2) and LED current (W3). A clockwise rotation will increase the resistance resulting in a lower operating frequency, lower OVP and lower LED current. Use an ohmmeter to measure the adjusted resistance value. 3. W3 LED Current – The LED channel current (ICH) can be adjusted from 90mA to 360mA by W3. RCS = 0.135Ω is calculated by setting VIN = 12V, VOUT = 32V, ICH = 360mA, L1/L2 = 10µH, fOSC = 1MHz. RCS should be reduced when ICH = 360mA and fOSC is less than 1MHz or the IC will enter into the power limit mode. The default parameters of the evaluation board are: VIN = 12V, VOUT = 32V, fOSC = 1MHz (W1= 9kΩ), VOVP = 39V (W2 = 13kΩ), ICH = 120mA (W3 =13.2kΩ), RCS = 0.135Ω, L1/L2 =10µH. Note that W1, W2 and W3 are set at the factory. The operating temperature is from -40°C to +125°C. 4. Excel Calculator – W1, W2 and W3 cannot be randomly changed. Please use the IS32BL3552 Excel Calculator to define the system parameters. It is recommended to maintain the switching duty cycle less than 70% when ICH > 300mA and fOSC > 0.8MHz. Otherwise the switching MOSFET and Diode will have large power losses, will heat up resulting in reduced power conversion efficiency. Note: Please follow the suggested procedures below when modifying the DEMO board parameters. 1. W1 Set Switch Frequency – Clockwise rotation of W1 will adjust the switching frequency (fOSC) from 1MHz to 100kHz and the inductor L1/L2 peak current (IPEAK) will increase from 1.8 A to 5.17A. For operation with TA > 85°C, the MOSFET should be thermally protected with the addition of a heat sink. Also the temperature stability of magnetic saturation current for inductor and the temperature stability of compensation capacitor for COMP should be selected for elevated temperature operation. Caution: An IPEAK of 5.17A is too high for the installed 10µH inductor L1/L2. A higher IPEAK current will affect other component selections such as inductor L1/L2 and current sense resistor RCS (R1||R2). We recommend a lower fOSC by using a 47µH inductor instead of 10µH to keep IPEAK below 2.22A. Note: A higher inductor value will reduce the PWM dimming contrast. For the default L1/L2 value, the contrast is 1000:1. Choosing a smaller inductor like 4.7µH will increase the contrast to 2000:1(Max.). Notice that the inductor should be higher than LCCM(Min.). VIN L1/L2 2 1 VIN GND 2 1 6 22uF/50V Vo GND VCC STATUS VCC OUT DIM EN 7 R6 10k DIM R7 10k EN 5 4 R13 2R 3 2 9 R5 R8 C11 300k 300k NC R3 0--500K 43k C7 R15 220nF R1 0.27R C2 NC R2 0.27R 1 R10 1M C4 22uF/100V 22uF/100V R11 43K 2X10 820pF 0--200K W2 EN OVP DIM CH1 16 10 13 CH1 CH2 RT Iset NC 15 R9 6.8k W3 8 C3 C8 STATUS R9' R12 C10 220nF 0R VCC CH2 W1 C9 220nF Q1 13N06 IS32BL3552 STATUS 2 1 VIN R14 100k Vo SS310 CS C6 D1 0R C5 NC 2.2uF 2 1 10uH U1 R4 0R C1 FB COM GND 12 0--20K V0 CH1 CH2 1 2 3 1k IS32BL3552 Figure 2: IS32BL3552 Application Schematic Integrated Silicon Solution, Inc. – www.issi.com Rev. C, 07/24/2015 2 IS32BL3552 BOOST TYPE LED DRIVER WITH 2-CHANNEL CURRENT SOURCE BILL OF MATERIALS Name Symbol LED Driver U1 Inductor L1/L2 Diode D1 Ferrite Bead Description Qty Supplier Part No. Boost backlight LED driver 1 ISSI IS32BL3552 IND,10µH±20%,SMD 1 Würth Elektronik 7447709100 Schottky Diode, SS310 SMD 1 FB 600R@100M SMD 1 NMOS Q1 100V N-Channel MOSFET SMD 1 Fairchild FQD19N10L Resistor R1,R2 RES,0.27Ω,1/10W,±1%,SMD 2 Yageo RL0805FR-070R27L Resistor R3,R4 RES,0Ω,1/10W,±1%,SMD 2 Yageo RL0805FR-0700RL Resistor R5,R8 RES,300k,1/10W,±5%,SMD 2 Yageo RC0805JR-07300KL Resistor R6,R7 RES,10k,1/10W,±5%,SMD 2 Yageo RC0805JR-0710KL Resistor R9 RES,6.8k,1/10W,±1%,SMD 1 Yageo RC0805FR-076K8L Resistor R10 RES,1M,1/10W,±1%,SMD 1 Yageo RC0805FR-071ML Resistor R11 RES,43k,1/10W,±1%,SMD 1 Yageo RC0805FR-0743KL Resistor R12 RES,43k,1/10W,±1%,SMD 1 Yageo RC0805FR-0743KL Resistor R13 RES,2Ω,1/10W,±5%,SMD 1 Yageo RC0805JR-072RL Resistor R14 RES,100k,1/10W,±5%,SMD 1 Yageo RC0805JR-07100KL Resistor R15 RES,1k,1/10W,±5%,SMD 1 Yageo RC0805JR-071KL Capacitor C1 CAP,22µF,50V,±20%,SMD 1 Capacitor C3,C4 CAP,22µF,100V,±20%,SMD 2 Capacitor C6 CAP, 2.2µF,16V,±10%,SMD 1 Yageo CC0805JKX7R7BB225 Capacitor C7,C9,C10 CAP,0.22µF,16V,±10%,SMD 3 Yageo CC0805JKX7R7BB224 Capacitor C8 CAP,820pF,16V,±10%,SMD 1 Yageo CC0805JKX7R7BB821 Variable Resistor W1 RES,0~500k 1 Variable Resistor W2 RES,0~200k 1 Variable Resistor W3 RES,0~20k 1 R9’,C2,C5,C11 Not Connect 4 SS310 Bill of materials, refer to Figure 2 above. Integrated Silicon Solution, Inc. – www.issi.com Rev. C, 07/24/2015 3 IS32BL3552 BOOST TYPE LED DRIVER WITH 2-CHANNEL CURRENT SOURCE 10 10 4 2 1 2 1 4 5 8 8 4 4 5 8 2 1 3 4 2 3 2 4 1 1 8 3 2 1 3 2 1 10 10 Figure 3: Board Component Placement Guide - Top Layer Figure 4: Board PCB Layout - Top Layer Integrated Silicon Solution, Inc. – www.issi.com Rev. C, 07/24/2015 4 IS32BL3552 BOOST TYPE LED DRIVER WITH 2-CHANNEL CURRENT SOURCE 10 10 4 2 1 2 1 4 5 8 8 4 4 5 8 2 1 3 4 2 3 2 4 1 1 8 3 2 1 3 2 1 10 10 Figure 5: Board Component Placement Guide - Bottom Layer Figure 6: Board PCB Layout - Bottom Layer Copyright © 2015 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances Integrated Silicon Solution, Inc. – www.issi.com Rev. C, 07/24/2015 5