Texas Instruments LM3508TL Evaluation Board LM3508TLEV LM3508TLEV 데이터 시트
제품 코드
LM3508TLEV
SW
GND
LM3508
L1
COUT
CIN
EN
DIM
PGND
OUT
ILED
SET
IN
R1
OPEN
2 3 4 LEDs
RSET
VIN
ISET
IOUT
VOUT
SW
EN
DIM
PGND
D1
D2
D3
D4
User's Guide
SNVA223 – June 2007
AN-1593 LM3508 Evaluation Board
1
Introduction
The LM3508 is a synchronous step-up DC/DC converter designed for white LED applications. The
evaluation board is set up to drive four standard V
evaluation board is set up to drive four standard V
F
white LEDs from a 2.7 V to 5.5 V input supply. A fifth
LED can be placed across the R1 pad for testing up to five low VF LEDs. The LED current is set using the
RSET resistor via the equation I
RSET resistor via the equation I
LED
= 0.2V/RSET. The evaluation board comes with RSET = 10
Ω
for
approximately 20 mA LED current. LED dimming is achieved by applying a PWM waveform of up to 100
kHz to the DIM pin.
kHz to the DIM pin.
2
Schematic
3
Bill of Materials
Designator
Component
Part Number
Manufacturer
U1
LM3508TL, µSMD 9-bump
LM3508
National Semiconductor
L
22 µH, ISAT = 330 mA
VLF3010AT-220MR33
TDK
CIN
1 µF, 10V Ceramic
C1608JB1A105M
TDK
COUT
1 µF, 25V Ceramic
C1608JB1E105M
TDK
C3216X7R1E105K
D1–D3
White LED
LW M67C
Osram
R1
0
Ω
Resistor
CRCW0603
Vishay
R1
10
Ω
Resistor
CRCW060310R0F
Vishay
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1
SNVA223 – June 2007
AN-1593 LM3508 Evaluation Board
Copyright © 2007, Texas Instruments Incorporated