PAM2805 User Guide

PAM2805
EVB User Guide
PAM2805 SOT23-6 EV Board User Guide
AE Department
1. Revision Information
Date
2011/11
Revision
V1.0
Description
Initial Release
Comment
2. PAM2805 General Description
The PAM2805 is a step-up DC-DC WLED driver with 3 modes cycling function (100%brightness,
25%brightness and 8.5Hz blinking). The unique 3 modes cycling function can eliminate the needs of extra
functional MCU or IC.
The PAM2805 can deliver up to 750mA output current by setting an external resistor. The PAM2805
switches at a 1.0MHz constant frequency, allowing for the use of small value external inductor and ceramic
capacitors.
A low 95mV feedback voltage reduces the power loss in the Rs for better efficiency. With its internal 2A,
100mΩ NMOS switch, device can provide high efficiency even at heavy load.
The PAM2805 is available in SOT23-6 package.
3. Key Features
z 3 Modes Cycling Function:
Power Off
Power Off
< 5s
< 5s
Bright
Dimming
Blinking
Power Off
< 5S
z Reset to Bright mode if Power Off
time more than 5S
z Adjustable Output Current: up to
z 8.5Hz Blinking Mode
z Low Start-Up Voltage: 0.9V(Typ.)
z Low SW on Resistance: 100mΩ
z Over Temperature Protection
z Over Voltage Protection
z SOT23-6 Package
z Pb-Free Package
750mA
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.
PAM2805
EVB User Guide
4. EV Board Schematic
Vin
D1
Vo
6
L1
Cin
3
Vin
BLK
GND
1
SW
IC1
FB
5
4
WLED
Co
FB
Rs
2
C1
Vout
5. EVB PAM2805 Description
PAM2805 EVB is an evaluation board for the PAM2805 SOT23-6, a WLED driver. The board is targeted to
be used in providing a simple and convenient evaluation environment for the PAM2805. Requires parts,
power supply connectors etc. on the board, which makes it easy to be evaluated.
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.
PAM2805
EVB User Guide
6. EV Board View
EV board operational sequence:
1. Connect LED+ to anode of the power LED, the cathode connect to LED2. Connect Vin and GND to power supply.
7. Resistor Select for LED Current Setting
ILED = VREF/RS
ILED
350mA
750mA
(VREF = 0.095V; RS =RS1//RS2)
Rs1
0.27Ω
0.27Ω
Rs2
NC
0.22Ω
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.
PAM2805
EVB User Guide
8. External Components Selection
Input & output Capacitors (Cin, Co)
(1) For lower output ripple, low ESR is required.
(2) Low leakage current needed, 10uF, X5R/X7R ceramic recommend.
Blinking Capacitors (C1)
(1) Low leakage current needed, 1uF, X5R/X7R ceramic recommend.
Iset resistors (Rs1, Rs2)
(1) RS set the power LED current, ILED=0.095V/RS, RS= RS1// RS2, See above table
(2) For accurate LED Current 1% tolerance is required.
(3) Pay attention to power dissipation to these resistors for flowed high current.
Inductor (L1)
(1) Low DCR for good efficiency
(2) Inductor rated current must higher than the output current
Diode (D1)
(1) Consult the input voltage range and the output current, SS22 recommend
9. External Board BOM List
Item
Value
Cin
10µF
Co(1)
10µF
C1
1uF
Rs1
L1
D1
IC1
PCB
0.27Ω
2.2µH
Note:
Type
X5R/X7R,
Ceramic/0805
X5R/X7R,
Ceramic/0805
X5R/X7R,
Ceramic/0603
0805
2A/20V
PAM2805
PAM2805 EVB
Rating
10V
10V
25V
1%
>2A
Description
Vender and Part No.
TAIYO YUDEN
Input coupling CAP,
EMK212ABJ106KD-T
TAIYO YUDEN
Output CAP
EMK212ABJ106KD-T
TAIYO YUDEN
Blinking CAP,
TMK107 BJ105KA-T
LED current set RES
Inductor
CD43-2.2uH
Schottky Diode
SS22
SOT23-6
1. For single cell application, It will be much better to add a 10µF output CAP to improve the
efficiency.
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.
PAM2805
EVB User Guide
10. 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.