DESCRIPTION
The IS32BL3554 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 IS32BL3554 contains four 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 20mA to 180mA. 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 IS32BL3554 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.
FEATURES
Input voltage range: 4.5V to 33V
4-Channel LED current sinks, 180mA per string LED current adjustable from 20mA to 180mA 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
QUICK START
Figure 1: Photo of IS32BL3554 Evaluation Board
RECOMMENDED EQUIPMENT
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
≤ 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 IS32BL3554 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) 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).
2) 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
IS32BL3554-ZLA3-EB -40°C ~ +125°C (Automotive) eTSSOP-16, Lead-free
Integrated Silicon Solution, Inc. – www.issi.com
EVALUATION BOARD OPERATION
IS32BL3554 evaluation board drives four 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. The default parameters of the evaluation board are: VIN
= 12V, VOUT = 32V, fOSC = 1MHz (W1= 9kΩ), VOVP = 39V
(W2 = 13kΩ), ICH = 120mA (W3 = 3.2kΩ), 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.
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 1.8A to 5.17A.
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.).
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 IS32BL3554
operation is unstable if VOVP is set to less than VOUT.
3. W3 LED Current – The LED channel current (ICH)
can be adjusted from 45mA to 180mA by W3. RCS =
0.135Ω is calculated by setting VIN = 12V, VOUT = 32V,
ICH = 180mA, L1/L2 = 10µH, fOSC = 1MHz. RCS should be
reduced when ICH = 180mA and fOSC is less than 1MHz
or the IC will enter into the power limit mode.
4. Excel Calculator – W1, W2 and W3 cannot be
randomly changed. Please use the IS32BL3554 Excel Calculator to define the system parameters.
It is recommended to maintain the switching duty cycle less than 70% when ICH > 150mA and fOSC > 0.8MHz.
Otherwise the switching MOSFET and Diode will have large power losses, will heat up resulting in reduced power conversion efficiency.
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.
R4 0R C5 NC C1 22uF/50V VCC R14 100k C6 2.2uF R6 10k R7 10k R5 300k R8 300k C11 NC R12 43k R15 1k W1 0-500K C7 220nF L1/L2 10uH R13 2R Q1 13N06 R3 0R C2 NC R1 0.27R R2 0.27R D1 SS310 C9 220nF C10 220nF C3 22uF/100V C4 22uF/100V R10 1M R9 6.8k W3 0--20K C8 820pF R11 43K W2 0--200K VIN 6 VCC 5 STATUS 7 EN 2 DIM 9 RT 1 COM 8 OUT 4 CS 3 OVP 16 CH1 10 CH2 13 CH3 11 CH4 14 Iset 15 GND 12 IS32BL3554 U1 IS32BL3554 1 2 1 2 EN DIM STATUS EN DIM STATUS VCC VCC 1 2 3 4 5 V0 CH1 CH2 CH3 CH4 CH1 CH2 CH3 CH4 4X10 R9' NC 1 2 1 2 GND VIN GND Vo Vo FB 0R Figure 2: IS32BL3554 Application Schematic
BILL OF MATERIALS
Name Symbol Description Qty Supplier Part No.
LED Driver U1 Boost backlight LED driver 1 ISSI IS32BL3554
Inductor L1/L2 IND,10µH±20%,SMD 1 Elektronik Würth 7447709100
Diode D1 Schottky Diode, SS310 SMD 1 SS310
Ferrite Bead 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 RC0603JR-07300KL
Resistor R6,R7 RES,10k,1/10W,±5%,SMD 2 Yageo RC0603JR-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,±1%,SMD 1 Yageo RC0805FR-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
Integrated Silicon Solution, Inc. – www.issi.com 10 10 10 10 1 2 3 1 2 3 1 2 3 4 4 5 5 4 4 4 4 5 4 3 2 1 1 2 2 1 2 1 8 8 8 8
Figure 3: Board Component Placement Guide - Top Layer
10 10 10 10 1 2 3 1 2 3 1 2 3 4 4 5 5 4 4 4 4 5 4 3 2 1 1 2 2 1 2 1 8 8 8 8
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.
