Texas Instruments SLUU083A User Manual

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bq2400x Single and Two Cell

Li Ion Charge Management IC

With Integrated Power FET EVM

User’s Guide

July 2002

Advanced Analog Products

SLUU083A

IMPORTANT NOTICE

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Copyright 2002, Texas Instruments Incorporated

Trademarks

Preface

Read This First

About This Manual

This user’s guide describes the bq2400x evaluation module. The EVM conveniently evaluates a linear Li-ionbq2400xcharge-managementsolution for oneandtwo-cellbattery-packapplications. This guide describes a completedesigned-and-testedcharger, which delivers up to 1.2 A ofcontinuous-chargecurrent for oneortwo-cellapplications

How to Use This Manual

This document contains the following chapters:

-Chapter 1— Introduction

-Chapter 2— Test Summary

-Chapter 3— Physical Layouts

-Chapter 4— Bill of Materials

-Appendix A— Schematic

Related Documentation From Texas Instruments

-bq24001, bq24002, bq24003 data sheet, literature number SLUS462A

-bq24004, bq24005, bq24006 data sheet, literature number SLUS476

Trademarks

PowerPAD is a trademark of Texas Instruments.

Read This First

iii

Running Title—AttributeReference

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.2 Performance Specification Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

2 Test Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

 

2.1

Setup .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-2

 

 

2.1.1

I/O Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-2

 

 

2.1.2

Jumper-SelectableConfiguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-2

 

2.2

Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-2

 

 

2.2.1

For Single-CellApplications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-2

 

 

2.2.2

For Two-CellApplications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-3

3

Physical Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3-1

 

3.1

Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3-2

4

Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-1

 

4.1

Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-2

 

4.2

bq2400x Charge Status Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-3

A

Schematic . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A-1

Figures

3–1SLUP051 Board Layout Top Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2 3–2SLUP051 Board Layout Bottom Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3 3–3SLUP051 Top Assembly View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-2

 

 

Tables

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1–1

Performance Specification Summary (One Cell) . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . 1-2

1–2

Performance Specification Summary (Two Cell) . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . 1-3

4–2

SLUP051 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . 4-3

Contents v

Chapter 1

Introduction

This user’s guide describes the bq2400x Evaluation Module (SLUP051). The EVM conveniently evaluates a linear Li-ionbq2400xcharge-managementsolution for oneandtwo-cellbattery-packapplications. This guide describes a completedesigned-and-testedcharger, which delivers up to 1.0 A of continu-ous-chargecurrent for oneortwo-cellapplications.

Topic

 

Page

 

 

 

1.1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . 1-2

1.2

Performance Specification Summary . . . . . . . . . . . . . . . . . . . . . . . . . .

. 1-2

 

 

 

1-1

Background

1.1 Background

The bq2400x series ICs are advanced Li-Ionlinear charge management devices for highly integrated andspace-limitedapplications. They combinehigh-accuracycurrent and voltage regulation; FETpass-transistorandreverse-blockingSchottky; battery conditioning, temperature, orinput-powermonitoring; charge termination;charge-statusindication; and charge timer in a small,20-leadTSSOP PowerPAD package.

The bq2400x continuously measures battery temperature using an external thermistor. For safety reasons, the bq2400x inhibits charge until the battery temperature is within the user-definedthresholds. Alternatively, the user can monitor the input voltage to qualify charge. The bq2400x series then charge the battery in three phases: preconditioning, constant current and constant voltage. If the battery voltage is below the internallow-voltagethreshold, the bq2400x usestrickle-chargeto condition the battery. A preconditioning timer is provided for additional safety. Following preconditioning, the bq2400x applies aconstant-chargecurrent to the battery. An externalsense-resistorsets the magnitude of the current. Theconstant-currentphase is maintained until the battery reaches thecharge-regulationvoltage. The bq2400x then transitions to the constant voltage phase. The user can configure the device for cells with either coke or graphite anodes.

Charge is terminated by either of the following methods:

-Maximum time

-Minimum current detection

1.2Performance Specification Summary

This section summarizes the performance specifications of the SLUP051 EVM. Table 1–1gives the performance specifications of the hubs.

The bq2400x automatically restarts the charge if the battery voltage falls below an internal recharge threshold.

Table 1–1.Performance Specification Summary (One Cell)

Specification

Test Conditions

Min

Typ

Max

Units

 

 

 

 

 

 

 

Input dc voltage, VDC

 

4.9

5.0

V

Battery charge current, ICHG

J4 shorted, J3 open

0.4

0.5

0.6

A

 

 

 

 

J3 shorted, J4 open

0.9

1

1.1

 

 

 

 

 

 

 

 

 

 

Battery voltage regulation, VREG

J6 set to VCC

4.15

4.20

4.25

V

J6 set to GND

4.05

4.1

4.15

 

 

 

 

 

 

 

 

 

 

Therm fault

High, TBATMAX

J2 set to Therm

43

48

53

° C

Low, TBATMIN

J2 set to Therm

0

5

10

 

 

APG (user defined, see data sheet)

J2 set to APG

 

 

 

 

 

 

 

 

 

Power dissipation, PD

(VI-VO)× Iload

 

 

2.3

W

VI, for asingle-cell,should not exceed 5.3 VDC for the1-Acharge rate and 7.6 V for the0.5-Acharge rate. (VI is the input voltage to the bq2400x IC, pins 2 and 3. The power supply source voltage, at J1, is 0.1 V larger than VI because of the regulated voltage drop across the current sense resistor, during constant current regulation.)

If J2 is set to APG, then the chip will be disabled when the input is outside of this range: 4.02 V± 0.07 V and 10.76 V± 0.09 V.

1-2

Performance Specification Summary

Table 1–2.Performance Specification Summary (Two Cell)

Specification

Test Conditions

Min

Typ

Max

Units

 

 

 

 

 

 

 

Input dc voltage, VDC

 

9.1

9.5

V

Battery charge current, ICHG

J4 shorted, J3 open

0.4

0.5

0.6

A

 

 

 

 

J3 shorted, J4 open

0.9

1

1.1

 

 

 

 

 

 

 

 

 

 

Battery voltage regulation, VREG

J6 set to VCC

8.35

8.40

8.45

V

J6 set to GND

8.15

8.20

8.25

 

 

 

 

 

 

 

 

 

 

Therm fault

High, TBATMAX

J2 set to Therm

43

48

53

° C

Low, TBATMIN

J2 set to Therm

0

5

10

 

 

APG (user defined, see data sheet)

J2 set to APG

 

 

 

 

 

 

 

 

 

Power dissipation, PD

(VI-VO)× Iload

 

 

2.3

W

VI, for a2-cell,should not exceed 9.1 VDC for the1-Acharge rate and 10.6 V for the0.5-Acharge rate. (VI is the input voltage to the bq2400x IC, pins 2 and 3. The power supply source voltage, at J1, is 0.1 V larger than VI because of the regulated voltage

drop across the current sense resistor, during constant current regulation.)

If J2 is set to APG, then the chip will be disabled when the input is outside of this range: 4.02 V± 0.07 V and 10.76 V± 0.09 V.

Introduction 1-3

Chapter 2

Test Summary

This chapter shows the test setups used, and the tests performed, in designing the bq2400xEVM.

Topic

 

Page

 

 

 

2.1

Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . 2-2

2.2

Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. 2-2

 

 

 

Test Summary

2-1

 

Setup

2.1 Setup

The bq2400X EVM board requires a DC power source to provide input power and a single-celllithium-ionorlithium-polymerbattery to charge.

Note:

Other versions of the bq2400x IC can charge two-cellbattery packs.

The test setup connections and jumper setting selections are listed below.

2.1.1 I/O Connections

Jack

Connect to:

 

 

J1–VCC

Power source positive output

J1–GND

Power source negative output

J9–+

Positive lead of single lithium cell

J9– –

Negative lead of single lithium cell

J9 – VSENSE

Tie to battery’s positive terminal

J10

– THERM

Tie to thermistor lead in battery pack

J10

– GND

Tie to other thermistor lead (may be GND)

 

 

 

2.1.2Jumper-SelectableConfiguration

Jumper

Selection

 

 

J3

1-Acharge, use two jumpers placed horizontally; no jumpers on J4

J4

0.5-Acharge, use two jumpers placed horizontally, no jumpers on J3

J2

Adapter power good (APD) or battery’s thermistor

J5

Enable, on or off

J6

Regulation voltage, 4.2 V or 4.1 V (single cell), 8.4 V or 8.2 V (double cell)

J7

Timer, 3-hour(float, no jumper),4.5-hour,or6-hour

J8

Stat2 green diode, connect for bq24002/3/5/6/8

This jumper enables/disables the IC for bq24001/2/3/4/5/6. For bq24007/8, this jumper enables/ disables the change timer.

For bq24003/6/8 the evaluation board used two LED (red and green) in place of a single dull-colorLED. Therefore, when both LEDs are lit a yellow status is indicated.

2.2Test Procedures

2.2.1For Single-CellApplications

Set up the evaluation board as described above, by making the necessary I/O connections and jumper selections.

Note:

Before test and evaluation, it is important to verify that the maximum power dissipation on the IC is not exceeded. Pmax = 2.3 W.

Pdiss, single cell = (VI – 3 V) × ICHG where VI = VCC –0.1V

2-2

Test Procedures

Note:

VI for a single cell should not exceed 5.3 VDC for the1-Acharge rate and 7.6 V forthe .5-Acharge rate.

Adjust the input power supply for 5 V. The red LED should illuminate to indicate charging, unless there is a fault or the battery is fully charged.

The bq2400x enters preconditioning mode if the battery is below the LowV threshold. In this mode, the bq2400x trickle-chargeswith approximately 65 mA for approximately 23 minutes. If the battery does not reach the LowV threshold after this period, then the charge current is terminated and the bq2400x enters fault mode. The red LED flashes when in fault mode. This feature may be tested inthe .5-Acharge mode by using a5-Ω ,3-Wresistor in place of the battery. Fault mode is reset by toggling input power or enable pin.

Once the battery charges to the LowV-stopthreshold, the battery enters fast charge mode and charges at the selected ICHG level(0.5-1A).

The battery remains at the fast-chargemode until either the selected time expires or the battery charges to the selected regulation voltage.

The time-outfeature may be tested in the0.5-Acharge mode by using a 7 Ω ,3-Wresistor in place of the battery. Apply the resistor after the unit is powered.

If the battery discharges down to the HighV threshold, the charger starts fast charging. The refresh feature may be tested in the 0.5-Acharge mode by using a7-Ω,3-Wresistor in parallel with a fully charged battery.

The circuit has an overvoltage comparator for added protection. If the battery voltage exceeds this threshold for 330 ms, then the charger goes into fault mode. This may be tested by connecting an external power supply in place of the battery and adjusting the voltage above the threshold.

2.2.2For Two-CellApplications

Set up the evaluation board as described above, by making the necessary I/O connections and jumper selections.

Note:

Before test and evaluation, it is important to verify that the maximum power dissipation on the IC is not exceeded. Pmax = 2.3 W.

Pdiss, 2 cell = (VI – 6.8 V) × ICHG where VI = VCC –0.1V

Note:

With a two-cellbattery pack at 6 V, charging at 1 A, the IC power dissipation is temporarily as high as 3.1 W until the pack charges to 6.8 V. This condition is acceptable for the short time before the pack reaches 6.8 V.

Adjust the input power supply for 9.1 V. The red LED should illuminate to indicate charging, unless there is a fault or the battery is fully charged.

Test Summary

2-3