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User's Guide
SLUU464–November 2010
bq24450EVM
This user's guide describes the features and operation of the bq24450EVM Evaluation Module (EVM).
This EVM assists users in evaluating the bq24450 linear battery charger. The manual includes the
bq24450EVM bill of materials, board layout, and schematic.
Contents
1 Introduction .................................................................................................................. 2
1.1 EVM Features ..........................................
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Introduction www.ti.com 1 Introduction 1.1 EVM Features • Evaluation module for bq24450 (HPA691) • Charge controller for lead-acid batteries • Constant current and constant voltage modes • Accommodates external transistor in DPAK or TO-220 package • Programmable charge current • Pre-Charge for deeply discharged batteries 1.2 General Description The bq24450 contains all the necessary circuitry to optimally control the charging of lead-acid batteries. The IC controls the charging current as well a
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www.ti.com Equipment 1.4 Recommended Operating Conditions Table 2. Recommended Operating Conditions Symbol Description Min Typ Max Unit Vin, J1 Supply Voltage 9.5 10.0 10.5 V Vout, J4 Battery Voltage (3-cell lead-acid battery) 4 7.5 V Iin Supply Current 0 0.5 A Iout Charge Current 0 0.5 A 2 Equipment 2.1 Power Supplies Power Supply #1 (PS#1): Adjustable from 0 to ≥ 10 VDC at ≥ 1A; used for input J1. Power Supply #2 (PS#2): Adjustable from 0 to ≥ 10 VDC at ≥ 1.5A; used for Battery Load Board. 2.2
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Procedure www.ti.com Replacement circuit for a 3-cell lead acid battery. BAT+ to BAT– voltage tracks the power supply input voltage, minus 1 diode drop Figure 2. Battery Load Circuit – PR1010-2 4 Procedure 4.1 Pre-charge Turn on PS #1, preset to 10 VDC. Verify voltage on VM #1. Turn on PS #2, preset to 5.2 VDC. Adjust PS #2 such that VM #2 shows 5 VDC. Using VM #3, measure the voltage across the current sense resistor on Load #1. Multiply this value by a conversion factor of 10A/V. This is the p
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www.ti.com Functions and Features 5 Functions and Features 5.1 Changing Output Voltage and Charge Current This EVM is configured to charge a 3-Cell Lead Acid Battery with a maximum charge current of 450 mA. The EVM can be altered to charge lower or higher voltage batteries and can also be altered to have a lower or higher maximum charge current. Power Dissipation It is important to monitor the power dissipation in the external transistor, Q1. WARNING Q1 and the surrounding area of the PCB may be
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PCB Layout Guideline www.ti.com 5.2 Options for External Transistor Using a Transistor in a TO-220 package The EVM is populated with a DPAK transistor for Q1. However, if desired, a TO-220 transistor can be used instead. Three holes have been placed in the PCB in parallel with the DPAK pad. Remove the DPAK transistor and replace it with a TO-220 transistor. The top hole is the base, the middle hole is the collector, and the bottom hole is the emitter. Using a P-channel FET The EVM is populated w
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www.ti.com Bill of Materials, Board Layouts and Schematic 7 Bill of Materials, Board Layouts and Schematic 7.1 Bill of Materials Table 3. Bill of Materials Reference Value Description Size Part Number MFR Designator C1, C4 Open Capacitor, Ceramic 1206 Std Std C2, C5 1.0µF Capacitor, Ceramic, 25V, X5R, 10% 603 Std Std C3 0.1µF Capacitor, Ceramic, 25V, X7R, 10% 603 Std Std D1 ES2AA-13-F Diode SMA ES2AA-13-F Diodes, Inc. Q1 MJD32CT4 Transistor, PNP DPAK MJD32CT4 ST R1, R5, R13, R14, Open Resistor,
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Bill of Materials, Board Layouts and Schematic www.ti.com 7.2 Board Layout Figure 4. Top Assembly Layer Figure 5. Top PCB Layer 8 bq24450EVM SLUU464–November 2010 Submit Documentation Feedback © 2010, Texas Instruments Incorporated
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www.ti.com Bill of Materials, Board Layouts and Schematic Figure 6. Bottom PCB Layer 7.3 Schematic Figure 7. bq24450 EVM Schematic 9 SLUU464–November 2010 bq24450EVM Submit Documentation Feedback © 2010, Texas Instruments Incorporated
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Evaluation Board/Kit Important Notice Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end-product fit for general consumer use. Persons handling the product(s) must have electronics training and observe good engineering practice standards. As such, the goods being provided are not intended to be
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the t
