EVALUATION BOARD DATA SHEET

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EVALUATION BOARD DATA SHEET
EV156
Evaluation Board for the AAT3681A
500 mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Introduction
The AAT3681A evaluation board demonstrates single-cell lithium-ion/polymer battery charging from either a USB or
ADP port. The AAT3681A precisely regulates battery charge voltage and current for 4.2V (4.375V option) lithium-ion/
polymer battery cells. This device operates at an input voltage range from 4V to 7.5V. The charging current can be
set up to 500mA by an external resistor.
This document describes the evaluation board and the value for the set resistor. In addition, a schematic of the complete evaluation board's circuit (Figure 1) and the board layout (Figures 2 and 3) are provided. For additional information, please refer to the AAT3681A product datasheet.
Schematic
VBAT
VIN(ADP)
Enable
C1
10µF
JP2
U1
1
2
3
4
R8
8.06kΩ
EN
ISET
BAT
ADP
GND
GND
GND
STAT
8
7
6
5
C2
2.2µF
AAT3681A
JP1
0Ω
D1
RED
LED
R1
1kΩ
Figure 1: Evaluation Board Schematic.
Printed Circuit Board
Figure 2: Top Layer (not to scale).
Figure 3: Bottom Layer (not to scale). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202279A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 20, 2012
1
EVALUATION BOARD DATA SHEET
EV156
Evaluation Board for the AAT3681A
500 mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
Programming Charge Current
The charging current level is programmed with a resistor placed between the ISET pin and ground. The accuracy of the
constant charge current and preconditioning trickle charge current is dominated by the resistor tolerance. A 1% tolerance resistor is recommended.
The constant charge current can be programmed from 15mA to 500mA. Table 1 provides resistor values for commonly used constant charge current levels. Figure 4 shows the relationship between ICC and RSET.
Nominal ICHARGE (mA)
Set Resistor Value (kΩ)
500
450
400
350
300
250
200
150
100
50
40
30
20
15
3.24
3.57
4.12
4.64
5.36
6.49
8.06
10.7
16.2
31.6
38.3
53.6
78.7
105
Table 1: Recommended RSET Values.
Constant Charging Current
vs. Set Resistor Values
ICH (mA)
1000
100
10
1
1
10
100
1000
RSET (kΩ)
Figure 4: ICC vs. RSET.
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202279A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 20, 2012
EVALUATION BOARD DATA SHEET
EV156
Evaluation Board for the AAT3681A
500 mA USB Port or AC Adapter Li-Ion/Polymer Battery Charger
LED Status Output
The AAT3681A status pin function provides a visual indication of the status of a battery under charge. The status LED
is turned on by an internal MOSFET switch which connects the status pin to ground when the AAT3681A is in the preconditioning trickle charge, constant current charge, or constant voltage charge modes. The LED status indicator is
turned off when there is no battery charging or when the charge cycle is complete.
A series resistor (R1) is placed with the status indicator LED (D1) to limit the forward current through the LED. The
nominal value of R1 is 1kΩ; this value may be adjusted by the following formula:
ILED =
VCC - VF
R1
Use of the LED status indicator is optional. To disable this function, remove jumper JP1 which connects the LED to the
input supply.
Enable
The AAT3681A enable pin should be pulled to a logic high level to turn on the device.
AAT3681A EVAL Component Listing
Component
Part#
U1
R1
R8
JP1
C1
C2
JP2
LED1
AAT3681AIJS-T1
Chip Resistor
Chip Resistor
Chip Resistor
GRM21BR61A106KE19L
GRM21BR71A225KA01L
PRPN401PAEN
CMD15-21SRC/TR8
Description
USB/ADP Battery Charger; SC70JW-8 Package
1KW, 5%, 1/4W; 0603
8.06KW, 1%, 1/4W; 0805
0W, 5%, 1/4W; 0603
CER 10µF 10V 10% X5R 0805
CER 2.2µF 10V 10% X7R 0805
Connecting Header, 2mm zip
Red LED; 1206
Manufacturer
Skyworks
Vishay
Vishay
Vishay
Murata
Murata
Sullins Electronics
Chicago Miniature Lamp
Table 2: Component Listing.
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202279A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 20, 2012
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