IS31LT3948 MR16 DEMO Board Guide
Integrated Silicon Solution, Inc. – www.issi.com
1
R1.0, 18/12/2012
Description
IS31LT3948 is a PFM step-up DC-DC converter
designed for driving the white LED arrays for large size
LCD panel backlighting applications. With internal OVP
circuit, the chip and the system can be safe even if the
load is not connected. The device features external
PWM dimming or DC dimming, which allows the
flexible control of the backlighting luminance.
IS31LT3948 incorporates a unique FB scheme which
automatically adjusts the integrated DC/DC converter
to the optimum output voltage for the system,
maximizing the efficiency.
IS31LT3948 general DEMO board is used in general
lamp.
Features
Wide input voltage range: 5V-100V
Constant Current Output limited only by external
component selection (Note)
No loop compensation required
Internal over-voltage protection
Internal over-temperature protection
Note: The maximum output current is determined by Vout/Vin
ratio as well as the external components. If output current and
Vout/Vin ratio is high, high current components of inductor
and NMOS are needed.
Order information
Part Number
Package Type
IS31LT3948-GRLS2-EBMR16
SOP-8
Quick Start
Recommended Equipment
30VDC Power supply
LED panel (1W LED, 7 LEDs in series)
Multi-meter
Recommended Input and Output Ratings
Input: 10-17VDC
Output: 7LEDs in series/333mA
Note: The input voltage must be lower than the output
voltage(total Vf).
Absolute Maximum Ratings
Input voltage
≤ 35VDC
Output voltage
≤ 28VDC
Caution: Do not exceed the conditions listed above, otherwise
the board will be damaged or the output current will be
limited.
Procedure
The IS31LT3948 DEMO 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 negative terminal of the power supply
to the VIN1 pin and the positive terminal to the
VIN2 pin.
2)
Connect the negative of the LED panel (LED
arrays) to the LED- terminal.
3)
Connect the positive of the LED panel (LED arrays)
to the LED+ terminal.
4)
Turn on the power supply and the LED panel (LED
arrays) will be light.
Bill of Materials
No.
Name
Description
Ref Des.
Qty.
Mfr
1
AL Capacitor
470uF±10%,35V
C1
1
2
AL Capacitor
220uF±10%,50V,Low ESR
C3
1
3
SMD Capacitor
10uF±10%,50V
C4
1
4
SMD Resistor
2.4K
Ω±1%,1206
R1
1
5
SMD Resistor
24
KΩ±1%,0805
R4
1
6
SMD Resistor
27
0KΩ±1%,0805
R3
1
7
SMD Resistor
10KΩ±1%,0805
R7
1
8
SMD Resistor
0.21
Ω±1%,0805
R5
1
9
SMD Resistor
0.9Ω±1%,0805
R8
1
10
Schottky Diode
SS36,3A,60V,SMA
D1-D5
5
11
Diode
1N4007,1A,1000V,SMA
Ds
1
12
SMD Inductor
100uH,Isat≥3A
L1
1