BQ77908A Protector Datasheet

BQ77908A Datasheet, PDF, Equivalent


Part Number

BQ77908A

Description

Multi-Cell Lithium-Ion/Polymer Precision Protector

Manufacture

etcTI

Total Page 30 Pages
Datasheet
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BQ77908A
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bq77908A
SLUSAV5A – FEBRUARY 2012 – REVISED OCTOBER 2014
bq77908A Multi-Cell Lithium-Ion/Polymer Precision Protector
Not Recommended for New Designs
1 Features
• 4-, 5-, 6-, 7-, or 8-Series Cell Protection
• Individual Cell-Voltage Monitoring
• Low-Side NMOS FET Drive for Charge and
Discharge Control
• Compatible With 1-mΩ Current-Sense Resistor
• Supply-Voltage Range From 5.6 V to 40 V
• Integrated 3.3-V Micro-Power LDO Regulator
• Low Supply Current
– Normal Mode: 50 µA, Typical
– Shutdown Mode, LDO OFF: 5 µA, Typical
1
• 38-Pin TSSOP Package
• Internal 50-mA Automatic Cell Balancing
2 Applications
• Cordless Power Tools
• Cordless Lawn Equipment
• Electric Bikes
• UPS
• Light Electric Vehicles (LEV)
3 Description
The bq77908A is a battery protection and cell balancing device intended for Li-Ion and Li-Polymer battery packs.
The bq77908A monitors 4- to 8-series individual cell voltages and provides fast-acting outputs that may be used
to drive N-channel MOSFETs to interrupt the power path. Activation delays and recovery methods for safety
conditions are fully programmable in non-volatile memory.
Automatic cell balancing is provided using internal 50-mA cell circuits. A robust balancing algorithm ensures
optimum performance by maintaining all cell voltages in balance. Balancing may be configured to operate at all
times, only during charge, or can be disabled completely.
PART NUMBER
bq77908A
Device Information(1)
PACKAGE
TSSOP (38)
(1) For all available packages, see the orderable addendum at the end of the data sheet.
BODY SIZE (NOM)
9.70 mm × 4.40 mm
WARNING
The bq77908A-series integrated circuit helps system designers greatly enhance
the safety of their Li-Ion and Li-Polymer battery packs when integrated
effectively and in accordance with the instructions detailed in this document by
technically qualified personnel familiar with battery pack application safety. This
data sheet must be read in its entirety before working with the bq77908A.
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.

BQ77908A
Not Recommended for New Designs
bq77908A
SLUSAV5A – FEBRUARY 2012 – REVISED OCTOBER 2014
www.ti.com
Table of Contents
1 Features .................................................................. 1
2 Applications ........................................................... 1
3 Description ............................................................. 1
4 Revision History..................................................... 2
5 Description (continued)......................................... 3
6 Pin Configuration and Functions ......................... 4
7 Specifications......................................................... 5
7.1 Absolute Maximum Ratings ...................................... 5
7.2 Handling Ratings....................................................... 6
7.3 Recommended Operating Conditions....................... 6
7.4 Thermal Information .................................................. 7
7.5 Electrical Characteristics........................................... 8
7.6 Serial Communication Interface (for Configuration
Only)......................................................................... 10
8 Detailed Description ............................................ 11
8.1 Overview ................................................................. 11
8.2 Functional Block Diagram ....................................... 11
8.3 Feature Description................................................. 11
8.4 Device Functional Modes........................................ 25
8.5 Programming and Register Maps ........................... 26
9 Application and Implementation ........................ 37
9.1 Application Information............................................ 37
10 Device and Documentation Support ................. 52
10.1 Documentation Support ........................................ 52
10.2 Trademarks ........................................................... 52
10.3 Electrostatic Discharge Caution ............................ 52
10.4 Glossary ................................................................ 52
11 Mechanical, Packaging, and Orderable
Information ........................................................... 52
4 Revision History
Changes from Original (February 2012) to Revision A
Page
• Deleted the reference to medical equipment in the Applications section............................................................................... 1
• Changed the minimum values for discharge and charge short circuit ................................................................................ 12
• Added two table notes to Table 2......................................................................................................................................... 12
• Added further detail to the DPCKN description .................................................................................................................... 13
• Deleted an incorrect cross-reference label .......................................................................................................................... 15
• Added a default to Discharge Overcurrent Detection Delay Settings ................................................................................. 31
• Added new table notes ........................................................................................................................................................ 31
• Added a new WARNING ..................................................................................................................................................... 31
• Added a default to SCD Delay Settings .............................................................................................................................. 32
• Changed the delay for 0000 in Charge Short-Circuit Delay-Time Settings.......................................................................... 33
• Added a new table note ....................................................................................................................................................... 33
• Changed the Cell-Balance Enable Control table ................................................................................................................. 34
• Added application disclaimer note to the Application and Implementation section.............................................................. 37
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Features Product Folder Sample & Buy Technical Documents Tools & Software Support & Community bq77908A SLUSAV5A – FEBRUA RY 2012 – REVISED OCTOBER 2014 bq7790 8A Multi-Cell Lithium-Ion/Polymer Preci sion Protector Not Recommended for New Designs 1 Features • 4-, 5-, 6-, 7-, or 8-Series Cell Protection • Indivi dual Cell-Voltage Monitoring • Low-Si de NMOS FET Drive for Charge and Discha rge Control • Compatible With 1-mΩ C urrent-Sense Resistor • Supply-Voltag e Range From 5.6 V to 40 V • Integrat ed 3.3-V Micro-Power LDO Regulator • Low Supply Current – Normal Mode: 50 µA, Typical – Shutdown Mode, LDO OFF : 5 µA, Typical 1 • 38-Pin TSSOP Pa ckage • Internal 50-mA Automatic Cell Balancing 2 Applications • Cordless Power Tools • Cordless Lawn Equipment • Electric Bikes • UPS • Light E lectric Vehicles (LEV) 3 Description T he bq77908A is a battery protection and cell balancing device intended for Li- Ion and Li-Polymer battery packs. The bq77908A monitors 4- to 8-series individual cell voltages and pr.
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