Texas Instruments bq20z95EVM-001 User Manual

User's Guide

SLUU275 – October 2006

bq20z95EVM-001 SBS 1.1 Impedance Track™ Technology

Enabled Battery Management Solution Evaluation Module

This evaluation module (EVM) is a complete evaluation system for the bq20z95/bq29412 battery
management system. The EVM includes one bq20z95/bq29412 circuit module, an EV2300 PC interface
board for gas gauge interface, a PC USB cable, and Windows™-based PC software. The circuit module
includes one bq20z95 integrated circuit (IC), one bq29412 IC, and all other onboard components
necessary to monitor and predict capacity, perform cell balancing, monitor critical parameters, protect the
cells from overcharge, over-discharge, short-circuit, and overcurrent in 2-, 3- or 4-series cell Li-ion or
Li-polymer battery packs. The circuit module connects directly across the cells in a battery. With the
EV2300 interface board and software, the user can read the bq20z95 data registers, program the chipset
for different pack configurations, log cycling data for further evaluation, and evaluate the overall
functionality of the bq20z95/bq29412 solution under different charge and discharge conditions.

Contents

1 Features ....................................................................................................................... 2

2 bq20z95-Based Circuit Module ............................................................................................ 2

3 bq20z95 Circuit Module Schematic ....................................................................................... 3

4 Circuit Module Physical Layouts and Bill of Materials .................................................................. 4

5 EVM Hardware and Software Setup ...................................................................................... 9

6 Troubleshooting Unexpected Dialog Boxes .............................................................................. 9

7 Hardware Connection ....................................................................................................... 9

8 Operation .................................................................................................................... 11

9 Calibration Screen.......................................................................................................... 13

10 Pro (Advanced) Screen .................................................................................................... 15

11 Pack Assembly and The bq20z95 ....................................................................................... 16

12 Related Documentation from Texas Instruments ...................................................................... 17

Trademarks ................................................................................................................. 17

1 bq20z95EVM-001 Layout (Silk Screen) .................................................................................. 4

2 Top Assembly ................................................................................................................ 5

3 Top Layer ..................................................................................................................... 5

4 Bottom Layer ................................................................................................................. 5

5 Bottom Assembly ............................................................................................................ 6

6 Schematic ..................................................................................................................... 8

7 bq20z95 Circuit Module Connection to Cells and System Load/Charger ........................................... 10

8 SBS Data Screen........................................................................................................... 11

9 Data Flash Screen, 1st Level Safety Class ............................................................................. 12

10 Calibration Screen.......................................................................................................... 14

11 Pro (Advanced) Screen .................................................................................................... 15

12 Connection Sequence ..................................................................................................... 16

13 Fuel Gauging Command .................................................................................................. 16

1 Ordering Information ........................................................................................................ 2

2 Components and Flash-Memory Settings for Different Precharge Modes ........................................... 4

3 Bill of Materials ............................................................................................................... 7

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List of Figures

List of Tables

Enabled Battery Management Solution Evaluation Module

Features

1 Features

1.1 Kit Contents

1.2 Ordering Information

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4 Performance Specification Summary ..................................................................................... 9

5 Circuit Module to EV2300 Connections ................................................................................. 10

• Complete evaluation system for the bq20z95 SBS 1.1-compliant advanced gas gauge with Impedance
Track™ technology and bq29412 independent overvoltage protection IC

• Populated circuit module for quick setup

• PC software and interface board for easy evaluation

• Software that allows data logging for system analysis

• bq20z95/bq29412 circuit module

• EV2300 PC interface board

• Software CD with the evaluation software

• Connection cable to interface board

• Set of support documentation

• EV2300 USB interface board

EVM PART NUMBER CHEMISTRY CONFIGURATION CAPACITY

bq20z95EVM-001 Li-ion 2, 3, or 4 cell Any

2 bq20z95-Based Circuit Module

The bq20z95/bq29412-based circuit module is a complete and compact example solution of a bq20z95
circuit for battery management and protection of Li-ion or Li-polymer packs. The circuit module
incorporates a bq20z95 battery monitor IC, bq29412 independent overvoltage protection IC, and all other
components necessary to accurately predict the capacity of 2-, 3-, or 4-series cells.

2.1 Circuit Module Connections

Contacts on the circuit module provide the following connections:

• Direct connection to the cells: 1N (BAT-), 1P, 2P, 3P, 4P (BAT+)

• To the serial communications port (SMBC, SMBD)

• The system load and charger connect across PACK+ and PACK-

• To the system-present pin (SYS PRES)

Table 1. Ordering Information

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2.2 Pin Descriptions

3 bq20z95 Circuit Module Schematic

This section contains information for modifying and choosing a precharge mode for bq20z95/bq29412
implementation.

3.1 Schematic

The schematic follows the bill of materials in this user's guide.

bq20z95 Circuit Module Schematic

PIN NAME DESCRIPTION

1N -ve connection of first (bottom) cell
1P +ve connection of first (bottom) cell
2P +ve connection of second cell
3P +ve connection of third cell

4P +ve connection of fourth (top) cell
SMBC Serial communication port clock
SMBD Serial communication data port

SYS PRES System present pin (if low, system is present)

PACK- Pack negative terminal

VSS Pack negative terminal

PACK+ Pack positive terminal

3.2 Modifications for Choosing Particular Precharge Mode

In order to charge, the charge FET (CHG-FET) must be turned on to create a current path. When the
V

is 0 V and CHG-FET = ON, the V

(BAT)

voltage for the device is too low to operate. This function has three possible configurations, and the IC can
be easily configured according to the application needs. The three modes are 0-V Charge FET mode,
Common FET mode, and Precharge FET mode.

1. 0-V Charge FET mode - Dedicates a precharge current path using an additional FET (ZVCHG-FET) to
sustain the PACK+ voltage level.

2. Common FET mode - Does not use a dedicated precharge FET. The charge FET (CHG-FET) is set to
ON state as default.

3. Precharge FET mode - Dedicates a precharge current path using an additional open-drain (OD) pin
drive FET (PCHG-FET) to sustain the PACK+ voltage level.

To use a particular mode of charging with the EVM, add or remove some elements shown in Table 2 , and
use the given settings of DF.Configuration, ZVCHG1, 0.

is as low as the battery voltage. In this case, the supply

(PACK)

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Enabled Battery Management Solution Evaluation Module

Circuit Module Physical Layouts and Bill of Materials

Table 2. Components and Flash-Memory Settings for Different Precharge

MODE RESISTORS PRECHG FET ZVCHG1 ZVCHG0

1. 0-V Chg (default) R21, R28 Q3 0 0

2. Common FET R24 Q2 0 1

3. Precharge R23, R28 Q3 1 0

For more details about precharge operation and mode choices, see the bq20z95 data sheet at
(SLUS757 ).

3.3 Testing Fuse-Blowing Circuit

To prevent the loss of board functionality during the fuse-blowing test, the actual chemical fuse is not
provided in the circuit. FET Q4 drives TP3 low if a fuse-blow condition occurs; so, monitoring TP3 can be
used to test this condition. Fuse placement on the application board is shown in the bq20z95 data sheet
reference-board schematic.

4 Circuit Module Physical Layouts and Bill of Materials

This section contains the board layout, bill of materials, and assembly drawings for the bq20z95/bq29412
circuit module.

4.1 Board Layout

This section shows the dimensions, PCB layers (Figure 1 through Figure 5 ), and assembly drawing for the
bq20z95 module.

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Modes

Figure 1. bq20z95EVM-001 Layout (Silk Screen)

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Circuit Module Physical Layouts and Bill of Materials

Figure 2. Top Assembly

Figure 3. Top Layer

Figure 4. Bottom Layer

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Circuit Module Physical Layouts and Bill of Materials

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Figure 5. Bottom Assembly

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