PAM2841 EVB User Guide

PAM2841
EVB User Guide
PAM2841EV Board User Guide
AE Department
1. Revision Information
Date
2008/03/19
2013/01
Revision
V1.0
V1.1
Description
Initial Release
Update EVB Schematic and View
Comment
2. EV Board Schematic
Figure 1
3. EVB PAM2841 EB7CFA Description
PAM2841 EB7CFA evaluation board is a fully assembled and tested circuit board that evaluates the
PAM2841 white LED driver. The circuit operates from 2.5V to 5.5V and drives white LEDs in series with a
constant current.
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
PAM2841
EVB User Guide
4. EV Board View
LED+
LED-
Figure 2
EV board operational sequence:
a. Connect ENA to high (Vin)
b. Preset the power supply to between 2.5V and 5.5V.
c.
Turn off the power supply.
d. Connect positive power supply terminal to Vin.
e. Connect power supply ground to EV board GND.
f.
Turn on the power supply and verify that the LEDS are lit.
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
PAM2841
EVB User Guide
5. EV Board BOM List
Item
Value
Type
Rating
Description
C1
10µF
X5R/X7R,Ceramic/1210
10V
Input coupling CAP
C2
1µF
X5R/X7R, Ceramic/0805
10V
Vin coupling CAP
C3
1µF
X5R/X7R, Ceramic/1210
50V
Output CAP
C4
10nF
X5R/X7R, Ceramic/0805
10V
Comp CAP
C5
1nF
X5R/X7R, Ceramic/0805
10V
Comp CAP
R1
R2
R3
R4
L1
D1
Q1
White LED
910K
27K
10
2K
22µH
0805
0805
0805
0805
1210
1210
SOT23
3.2V(typ) 3.5V(max) at 20mA
5%
5%
1%
5%
1A
1A
OVP Resistor
OVP Resistor
Iset Resistor
Comp Resistor
Inductor
Schottky diode
Nmosfet
Vender and Part No.
Murata
GRM21R71C106B
Murata
GRM21R71C105B
Murata
GRM21R71C105B
Murata
GRM21R71C103B
Murata
GRM21R71C102B
Murata LQH32CN220K
NihonES11QS04
6. External Components Selection
Input Capacitor (C1) and Output Capacitor (C3)
(1) C1 Low ESR needed, 10uF, X5R/X7R ceramic recommended;
(2) C3 Low ESR needed, 1µF, X5R/X7R (rating 50V) ceramic recommended.
Coupling Capacitor (C2) and Comp Capacitors(C4,C5)
(1) C2, Low ESR needed, 1µF, X5R/X7R ceramic recommended;
(2) C4, Low ESR needed, 10nF, X5R/X7R ceramic recommended;
(3) C5, Low ESR needed, 1nF, X5R/X7R ceramic recommended.
Iset Resistor (R3)
(1) R3 set the string’s LED current , Iled=0.2/R3;
(2) R3, 10±1% recommended;
OVP Resistors (R1, R2)
(1) Vovp=V *(R1+R2)/R2;
ov
(2) R1, 910K±10% recommended; R2,27K±10% recommended;
Inductor (L1)
(1) Low DCR needed, 22µH (rating 1A) recommended.
Schottky Diode (D1)
(1) NihonES11QS06(1A, 60V) recommended.
(2) B140 (1A, 40V) recommended.
Mosfet (Q1)
(1) 2N7002 recommended.
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
PAM2841
EVB User Guide
7. PCB Layout Guidelines
Decoupling Capacitors
(1) The capacitors (C2) need to place very close to the PAM2841’s pins.
Grounding
(1) The decoupling capacitors C2, C4 should each to be grounded to analog ground AGND;
(2) The capacitors C1, C3, R2 and R3 should each be grounded to power ground PGND;
(3) Connect the AGND and PGND islands by connecting the GND pins directly to the exposed backside
pad. Make no other connections between these separate ground planes.
Others
(1) Connect L1, SW, D1, C3 with short and wide connections;
(2) Place the OVP voltage setting-divider resistors (R1, R2) as close to the OV pin as possible. The
divider’s center trace should be kept short;
(3) Minimize the size of the SW node while keeping it wide and short. Keep the SW node away from the
feedback node and ground;
(4) Place the Iset resistors (R3) as close to the Iset pin as possible.
8. PCB Layout Example
Top Layer
Bottom Layer
This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice.
No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.