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Document Number: KT34676BUG
Freescale Semiconductor
Rev. 1.0, 2/2009
User’s Guide
Using the High Input Voltage Charger for
Single Cell Li-Ion Batteries
(KIT34676EPEVBE)
Contents
1Purpose
1 Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
This User Guide helps the Lithium-Ion (Li-Ion) battery
2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
charger designer understand the MC34676B and its
evaluation board. It illustrates the design procedure when
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Application Diagram 3 Application Diagram 3.1 Dual-Input Standalone Charger The MC34676B can be used as a dual-input standalone Li-Ion charger. Figure 1 is the typical application circuit. Two LEDs indicate the charge status. AC BAT USBOUT USB C4 BATDET C2 C1 C3 GND MC34676B PPR USBEN CHG OFF IMIN IUSB ISET ON R R R IMIN IUSB ISET Figure 1. The dual-input Li-Ion Charger 3.2 Embedded Charger When the MC34676B is embedded in the system, the system MCU can control the charger through the USBEN pin
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Evaluation Board Specification 4 Evaluation Board Specification The evaluation board is designed to work as a standalone charger, or as an embedded charger in a handheld system. Figure 3 shows its schematic circuit. The normal operation range of the evaluation board is: For AC charger: V = 4.3V, V = 6.8V AC_MIN AC_MAX I = 1200mA AC_MAX For USB charger: V = 4.3V, V = 5.85V USB_MIN USB_MAX I = 400mA USB_MAX TP1 AC 1 C1 C2 J1 1.0U F NC TP 16 HDR_1X2 TP 15 BA TDET AC TP3 USB BAT 1 C3 C4 J2
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Component Selection 5 Component Selection 5.1 Input capacitors C1 and C3 The input capacitor is used to minimize the input voltage transient that may cause instability. A ceramic capacitor of 1.0μF or above is required for most applications. X5R and X7R dielectrics have better temperature stability. The evaluation board uses 1.0μF X5R ceramic capacitors. Considering the maximum input voltage rating of the MC34676B is 28V, the input capacitor must have 16V DC rated voltage. 5.2 Output capacito
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Component Selection Table 2. The USB CC-mode Charge Current Settings Open Open 400mA Short Open 150mA Open Short 150mA Short Short 300mA 5.5 End-of-charge current setting resistors R10 and R11 The end-of-charge (EOC) current for both the AC charger and the USB charger can be set by the resistors R10 and R11. On the evaluation board, two resistors with one pin header jumper are used for the user to conveniently configure different EOC current values. Table 3 shows the EOC current with the differ
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Layout Design 6 Layout Design 6.1 Layout The KIT34676EPEVBE PCB board has two copper layers. The component side of the KIT34676EPEVBE is provided to locate all components. Figure 4 is an overview of the board, followed by the layout of each layer. Figure 4. The Overview of the Evaluation Board Figure 5. The Component Side Silkscreen Layer of the Evaluation Board Using the Dual 28V Input Voltage Charger with Linear Regulator, Rev. 1.0 6 Freescale Semiconductor
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Layout Design Figure 6. The Component Side Layer of the Evaluation Board Figure 7. The Solder Side Layer of the Evaluation Board Using the Dual 28V Input Voltage Charger with Linear Regulator, Rev. 1.0 Freescale Semiconductor 7
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Layout Design 6.2 Layout considerations • Place decoupling capacitors C1, C3 and C4 as close as possible to the AC pin, USB pin and BAT pin respectively. • Place the charge current setting resistor as close as possible to the current setting pin to minimize the parasitic capacitance between the current setting pin and ground. • Use wide traces to connect input power source to the AC pin and USB pin, and BAT pin to the battery. • To get better thermal performance, put the EPAD pin of the MC34676
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Evaluation Board Configuration 7 Evaluation Board Configuration 7.1 Pin Headers The J1 and J3 pin headers link the external power source to the AC pin or USB pin of the MC34676B respectively. It allows the user to measure the current from the power source to the evaluation board when using a current meter between pin 1 and pin 2 of J1 or J3. The default setting of the two pin headers is to short pins 1 and 2 of J1, and open pins 1 and 2 of J3. The J2 pin header links the BAT pin and the exter
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Evaluation Board Configuration Table 4. The Default Settings of the Pin Headers J11 Open J12 Shorted J13 Open 7.2 Connector Pads There are 14 connecting pads (TP1 to TP14 with corresponding names) on the evaluation board to let the user simply connect the board to their system. The GND pads link power ground of the MC34676B. The AC pad or USB pad connect an external power source to the evaluation board. The PPR, CHG, USBEN, BATDET, USBOUT, ISET, IUSB and the IMIN pads link to the correspondin
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Test Setup with the Evaluation Board 8 Test Setup with the Evaluation Board The test setup is shown in Figure 8 and Figure 9. Connect a DC power source with a larger than 2.0A current limit to the AC pad or a USB power port to the USB pad on the evaluation board. Connect the positive and negative polarities of the Li+ battery to the VBAT pad and the GND pad on the evaluation board respectively. Use a current meter and a voltage meter to measure the charge current and the voltage respectively.
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Bill of Material 9 Bill of Material Part Item Qty Value DESCRIPTION Footprint Mfr PN Reference 1 2 C1,C3 1.0UF CAP CER 1.0UF 16V 10% X5R 0603 CC0603 MURATA GRM188R61C105KA93 TDK C1608X5R1C105K 2 1 C2 NC No Connection CC0603 N/A N/A 3 2 C4,C5 1.0UF CAP CER 1.0UF 10V 10% X5R 0603 CC0603 MURATA GRM188R61C105KA61 CAP CER 1.0UF 6.3V 10% X5R 0603 TDK C1608X5R0J105K 4 1 D1 RED LED ULTA BRIGHT RED 30MA 5V LED_0603_ LITE ON LTST-C190KRKT SMT 0603 C1 5 1 D2 GREEN LED ULTRA-BRIGHT GREEN SMT LED_0603_ LITE
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References 10 References Following are URLs where you can obtain information on other Freescale products and application solutions: Products Links Data Sheet MC34676 www.freescale.com/files/analog/doc/data_sheet/MC34676.pdf Freescale’s Web Site www.freescale.com Freescale’s Analog Web Site www.freescale.com/analog Freescale’s Power Management www.freescale.com/powermanagement Using the Dual 28V Input Voltage Charger with Linear Regulator, Rev. 1.0 Freescale Semiconductor 13
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How to Reach Us: Home Page: www.freescale.com E-mail: support@freescale.com USA/Europe or Locations Not Listed: Freescale Semiconductor Technical Information Center, CH370 1300 N. Alma School Road Chandler, Arizona 85224 +1-800-521-6274 or +1-480-768-2130 support@freescale.com Information in this document is provided solely to enable system and software Europe, Middle East, and Africa: implementers to use Freescale Semiconductor products. There are no express or Freescale Halbleiter Deutschl
