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. 2 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 3