bq24704 Charger Datasheet

bq24704 Datasheet, PDF, Equivalent


Part Number

bq24704

Description

Host-Controlled Li-Ion and Li-Polymer Battery Charger

Manufacture

etcTI

Total Page 30 Pages
Datasheet
Download bq24704 Datasheet


bq24704
Not Recommended for New Designs
bq24704
www.ti.com........................................................................................................................................................................................................ SLUS838 – MAY 2009
Low Cost, Host-Controlled Li-Ion and Li-Polymer Battery Charger With Low Iq
FEATURES
1
2 NMOS-NMOS Synchronous Buck Converter
with 300 kHz Frequency and >95% Efficiency
30-ns Minimum Driver Dead-time and 99.5%
Maximum Effective Duty Cycle
High-Accuracy Voltage and Current Regulation
– ±0.5% Charge Voltage Accuracy
– ±3% Charge Current Accuracy
– ±3% Adapter Current Accuracy
– ±2% Input Current Sense Amp Accuracy
Integration
– Internal Loop Compensation
– Internal Soft-Start
Safety
– Dynamic Power Management (DPM) with
Status Indicator
– Charger Overcurrent Protection
– Battery Overvoltage Protection
– Thermal Shutdown
Supports Two, Three, or Four Li+ Cells
8 – 24 V AC/DC-Adapter Operating Range
Analog Inputs with Ratiometric Programming
via Resistors or DAC/GPIO Host Control
– Charge Voltage (4-4.512 V/cell)
– Charge Current (up to 8 A, with 10-m
Sense Resistor)
– Adapter Current Limit (DPM)
Status and Monitoring Outputs
– AC/DC Adapter Present with Programmable
Voltage Threshold
– DPM Loop Active (DPMDET)
– Current Drawn from Input Source
Charge Enable
24-pin, 4x4-mm QFN Package
Energy Star Low Iq
– < 10 µA Off-state Discharge Current
– < 1.5 mA Off-state Input Quiescent Current
APPLICATIONS
Notebook and Netbook Computers
Portable Data-Capture Terminals
Portable Printers
Medical Diagnostics Equipment
Battery Bay Chargers
Battery Back-Up Systems
DESCRIPTION
The bq24704 is a high-efficiency, synchronous
battery charger with integrated compensation offering
low component count for space-limited Li-Ion and
Li-Polymer battery charging applications. Charge
current and voltage programming allows high
regulation accuracies, and can be either hardwired
with resistors, or programmed by the system
power-management microcontroller using a DAC or
GPIOs.
The bq24704 charges two, three, or four series Li+
cells, supporting up to 8 A of charge current, and is
available in a 24-pin, 4x4-mm thin QFN package.
PACKAGE AND PIN-OUT
PVCC 1
CHGEN 2
ACN 3
ACP 4
ACDET 5
ACSET 6
24 23 22 21 20 19
bq24704
QFN - 24
TOP VIEW
18 DPMDET
17 CELLS
16 SRP
15 SRN
14 BAT
13 SRSET
7 8 9 10 11 12
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PowerPad is a trademark of Texas Instruments.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2009, Texas Instruments Incorporated

bq24704
Not Recommended for New Designs
bq24704
SLUS838 – MAY 2009........................................................................................................................................................................................................ www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (CONTINUED)
The bq24704 features Dynamic Power Management (DPM) and input power limiting. These features reduce
battery charge current when the input power limit is reached to avoid overloading the AC adapter when supplying
the load and the battery charger simultaneously. A highly-accurate current-sense amplifier enables precise
measurement of input current from the AC adapter to monitor the overall system power.
ADAPTER +
ADAPTER–
R10
2Ω
C1
2.2 µF
PP
Q1 (ACFET) Q2 (ACFET)
SI4435
SI4435
Controlled by
HOST
C2
R1 0.1 µF
432 kΩ
1%
RAC
0.01 Ω
C3
0.1 µF
ACGOOD
R2
66.5 kΩ
1%
VREF
R3
10 kΩ
GPIO
HOST
DAC
ADC
R4
10 kΩ
C4
1 µF
10 kΩ
R15
C5
100 pF
D2
BAT54
C6 C7
10 µF 10 µF
SYSTEM
ACN
ACP
ACDET
AGND
ACGOOD
SRSET
ACSET
VREF
bq24704
PVCC
HIDRV
PH
BTST
REGN
LODRV
PGND
C8
0.1 µF
C9
Q3(BATFET)
SI4435
Controlled by
HOST
Q4
FDS6680A
L1
8.2 µH
P
RSR
0.01 Ω
D1 BAT54 0.1 µF
C11
10 µF
C10
1 µF
C13
0.1 µF
Q5
FDS6680A
C14
0.1 µF
DPMDET
CELLS
CHGEN
VADJ
SRP
SRN
BAT
ISYNSET
IADAPT PowerPad
R6
20 kΩ
C15
0.1 µF
C12
10 µF
PACK+
PACK–
(1) Pull-up rail could be either VREF or other system rail.
(2) SRSET/ACSET could come from either DAC or resistor dividers.
(3) VIN = 20 V, VBAT = 3-cell Li-Ion, ICHARGE = 3 A, IADAPTER_LIMIT = 4 A
Figure 1. Typical System Schematic, Voltage and Current Programmed by DAC
2 Submit Documentation Feedback
Product Folder Link(s) :bq24704
Copyright © 2009, Texas Instruments Incorporated


Features Not Recommended for New Designs bq24704 www.ti.com............................ ....................................... ....................................... ....................................... ....................................... ................ SLUS838 – MAY 2009 L ow Cost, Host-Controlled Li-Ion and Li- Polymer Battery Charger With Low Iq FE ATURES 1 •2 NMOS-NMOS Synchronous Buc k Converter with 300 kHz Frequency and >95% Efficiency • 30-ns Minimum Drive r Dead-time and 99.5% Maximum Effective Duty Cycle • High-Accuracy Voltage a nd Current Regulation – ±0.5% Charge Voltage Accuracy – ±3% Charge Curre nt Accuracy – ±3% Adapter Current Ac curacy – ±2% Input Current Sense Amp Accuracy • Integration – Internal Loop Compensation – Internal Soft-Sta rt • Safety – Dynamic Power Managem ent (DPM) with Status Indicator – Cha rger Overcurrent Protection – Battery Overvoltage Protection – Thermal Shu tdown • Supports Two, Three, or Four Li+ Cells • 8 – 24 V AC/DC-Adapter Operating Range • Analog In.
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