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Introduction
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1
Introduction
1.1
Features
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Synchronous switch-mode battery charge controller for solar power
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Resistor-programmable up to 26-V battery voltage
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Input operating range: 5 V–28 V
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LED indication for charge status
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Test points for key signals available for testing purposes; easy probe hook-up.
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Jumpers available; easy-to-change setting
1.2
General Description
The bq24650 is a highly integrated switch-mode battery charge controller. It provides input voltage
regulation, which reduces charge current when input voltage falls below a programmed level. When the
input is powered by a solar panel, the input regulation loop maintains the panel at maximum power output.
The bq24650 offers a constant-frequency, synchronous PWM controller with high-accuracy current and
voltage regulation, charge preconditioning, charge termination, and charge status monitoring.
The bq24650 changes the battery in three phases: preconditioning, constant current, and constant
voltage. Charge is terminated when the current reaches one-tenth of the fast charge rate. A
programmable fast-charge timer provides a safety backup. The precharge timer is fixed at 30 minutes.
The bq24650 automatically restarts the charge cycle if the battery voltage falls below an internal threshold
and enters a low, quiescent-current sleep mode when the input voltage falls below the battery voltage.
The bq24650 supports the battery from 2.1 V to 26 V with VFB set to a 2.1-V feedback reference. The
charge current is programmed by selecting an appropriate sense resistor. The bq24650 is available in a
16-pin, 3.5x3.5 mm
2
, thin QFN package.
For details, see the bq24650 data sheet (
1.3
I/O Description
Table 1. I/O Description
Jack
Description
J1–VIN
Positive input
J1–PGND
Negative input
J2–VSYS
Connected to system
J2–VOUT
Connected to charger output
J2–PGND
Ground
J2–TS
Temperature qualification voltage Input
2
bq24650EVM Synchronous, Switch-Mode, Battery Charge Controller for Solar
SLUU444A – August 2010 – Revised October 2010
Power
Copyright © 2010, Texas Instruments Incorporated