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Features

➤

Conforms to battery manufactur

ers' charge recommendations for

cyclic and float charge

➤

Pin-selectable charge algorithms

Two-Step Voltage with

temperature-compensated

constant-voltage maintenance

Two-Step Current with

constant-rate pulsed current

maintenance

Pulsed Current: hysteretic,

on-demand pulsed current

➤

Pin-selectable charge termination

by maximum voltage,

∆

V, mini-

mum current, and maximum

time

➤ Pre-charge qualification detects

shorted, opened, or damaged cells

and conditions battery

➤ Charging continuously qualified by

temperature and voltage limits

➤ Internal temperature-compen-

sated voltage reference

➤ Pulse-width modulation control

Ideal for high-efficiency

switch-mode power conversion

Configurable for linear or

gated current use

➤

Direct LED control outputs dis

play charge status and fault con

ditions

General Description

The bq2031 Lead-Acid Fast Charge

IC is designed to optimize charging

of lead-acid chemistry batteries. A

flexible pulse-width modulation

regulator allows the bq2031 to con

trol constant-voltage, constant-

current, or pulsed-current charging.

The regulator frequency is set by an

external capacitor for design flexi-

bility. The switch-mode design keeps

power dissipation to a minimum for

high charge current applications.

A charge cycle begins when power is

applied or the battery is replaced.

For safety, charging is inhibited un-

til the battery voltage is within con-

figured limits. If the battery voltage is

less than the low-voltage threshold,

the bq2031 provides trickle-current

charging until the voltage rises into

the allowed range or an internal

timer runs out and places the

bq2031 in a Fault condition. This

procedure prevents high-current

charging of cells that are possibly

damaged or reversed. Charging is

inhibited anytime the temperature

of the battery is outside the config

urable, allowed range. All voltage

thresholds are temperature-

compensated.

The bq2031 terminates fast (bulk)

charging based on the following:

■

Maximum voltage

■

Second difference of cell voltage

(

∆

■

Minimum current (in constant-

voltage charging)

■

Maximum time-out (MTO)

After bulk charging, the bq2031 pro-

vides temperature-compensated

maintenance (float) charging to

maintain battery capacity.

Lead-Acid Fast-Charge IC

TMTO Time-out timebase input

FLOAT State control output

BAT Battery voltage input

VCOMP Voltage loop comp input

ICOMP Current loop comp input

IGSEL Current gain select input

SNS Sense resistor input

TS Temperature sense input

TPWM Regulator timebase input

PN203101.eps

16-Pin Narrow

DIP or SOIC

LED

/DSEL

LED

/TSEL

MOD

COM

LED

/QSEL

TPWM

TMTO

FLOAT

BAT

VCOMP

ICOMP

IGSEL

SNS

LED

/ Charge status output 3/

QSEL Charge algorithm select

input 1

COM Common LED output

System ground

5.0V

10% power

MOD Modulation control

output

LED

/ Charge status output 1/

TSEL Charge algorithm select

input 2

LED

/ Charge status output 2/

DSEL Display select input

Pin Connections

Pin Names

SLUS156–JUNE 1999 E

bq2031

Summary of content (19 pages)

PAGE 1
bq2031 Lead-Acid Fast-Charge IC Features - ➤ Conforms to battery manufacturers' charge recommendations for cyclic and float charge Ideal for high-efficiency switch-mode power conversion - Configurable for linear or gated current use ➤ Pin-selectable charge algorithms - Two-Step Voltage with temperature-compensated constant-voltage maintenance - Two-Step Current with constant-rate pulsed current maintenance - Pulsed Current: hysteretic, on-demand pulsed current ➤ Pin-selectable charge terminatio
PAGE 2
bq2031 TPWM Pin Descriptions TMTO This input uses an external timing capacitor to ground the pulse-width modulation (PWM) frequency. See equation 9. Time-out timebase input This input sets the maximum charge time. The resistor and capacitor values are determined using equation 6. Figure 9 shows the resistor/capacitor connection. FLOAT COM QSEL MOD Voltage loop compensation input LED1–3 Current gain select input DSEL TSEL Termination select input With QSEL, selects the charge algorithm.
PAGE 3
bq2031 n Fast charge termination n Maintenance charging n Charge regulation Chip On VCC 4.5V Charge Algorithms Temperature Checks On Three charge algorithms are available in the bq2031: n Present VLCO < VCELL < VHCO Two-Step Voltage Temperature in Range Test 1 ISNS < ICOND n Two-Step Current n Pulsed Current Temperature Out of Range or Thermistor Absent Voltage Regulation @ VFLT + 0.
PAGE 4
bq2031 test 2 before the bq2031 recognizes its “pass” criterion. If this second test passes, the bq2031 begins fast (bulk) charging. Thermal monitoring continues throughout the charge cycle, and the bq2031 enters the Charge Pending state anytime the temperature is out of range. (There is one exception; if the bq2031 is in the Fault state—see below—the out-of-range temperature is not recognized until the bq2031 leaves the Fault state.
PAGE 5
VBLK VFLT Voltage Maintenance Fast Charge Phase 1 VMIN Phase 2 ICOND Voltage Current IMAX Qualification bq2031 Current IMIN IFLT Time VBLK Current VFLT Voltage VMIN Maintenance ICOND Fast Charge Voltage Current IMAX Qualification Figure 2. Two-Step Voltage Algorithm Time ICOND Maintenance Current VBLK VFLT Voltage VMIN Voltage Current IMAX Qualification Figure 3. Two-Step Current Algorithm Fast Charge Time Figure 4.
PAGE 6
bq2031 Configuring Algorithm and Display Modes VCC QSEL/LED 3 , DSEL/LED 2 , and TSEL/LED 1 are bidirectional pins with two functions; they are LED driver pins as outputs and programming pins for the bq2031 as inputs. The selection of pull-up, pull-down, or no pull resistor programs the charging algorithm on QSEL and TSEL per Table 1 and the display mode on DSEL per Table 2. The bq2031 latches the program states when any of the following events occurs: 1. VCC rises to a valid level. 2.
PAGE 7
bq2031 The user must include a pull-up resistor from the positive terminal of the battery stack to VDC (and a diode to prevent battery discharge through the power supply when the supply is turned off) in order to detect battery removal during periods of voltage regulation. Voltage regulation occurs in pre-charge qualification test 1 prior to all of the fast charge algorithms, and in phase 2 of the Two-Step Voltage fast charge algorithm.
PAGE 8
bq2031 n LTF—Low-temperature fault—Lower limit of the temperature range in which charging is allowed. VLTF = 0.6 * VCC VCC A resistor-divider network must be implemented that presents the defined voltage levels to the TS pin at the desired temperatures (see Figure 8). RT1 bq2031 The equations for determining RT1 and RT2 are: 13 Equation 4 NTC Thermistor VCC 0.6 ∗ VCC = 12 (VCC − 0.250 V ) RT1 ∗ (RT2 + R LTF ) 1+ (RT2 ∗ R LTF ) VSS RT2 t SNS Equation 5 TS 0.
PAGE 9
bq2031 Second Difference (∆2V) VCC Second difference is a Unitrode proprietary algorithm that accumulates the difference between successive samples of VBAT. The bq2031 takes a sample and makes a termination decision at a frequency equal to 0.008 * tMTO. Fast charge terminates when the accumulated difference is ≤ -8mV. Second difference is used only in the Two-Step Current algorithm, and is subject to a hold-off period (see below).
PAGE 10
bq2031 Voltage at the SNS pin is determined by the value of resistor RSNS, so nominal regulated current is set by: Table 4. Fixed-Pulse Period by IGSEL IGSEL TP (sec.) L 0.4 H 0.8 Z 1.6 Equation 8 IMAX = 0.250V/RSNS The switching frequency of the MOD output is determined by an external capacitor (CPWM) between the pin TPWM and ground, per the following: Equation 9 Pulsed Current Algorithm FPWM = 0.
PAGE 11
bq2031 Absolute Maximum Ratings Symbol Parameter Minimum Maximum Unit VCC VCC relative to VSS -0.3 +7.0 V VT DC voltage applied on any pin excluding VCC relative to VSS -0.3 +7.0 V TOPR Operating ambient temperature -20 +70 °C TSTG Storage temperature -55 +125 °C TSOLDER Soldering temperature - +260 °C TBIAS Temperature under bias -40 +85 °C Note: Commercial 10 s. max. Permanent device damage may occur if Absolute Maximum Ratings are exceeded.
PAGE 12
bq2031 Recommended DC Operating Conditions (TA = TOPR) Symbol Parameter Minimum Typical Maximum Unit Notes VCC Supply voltage 4.5 5.0 5.5 V VTEMP TS voltage potential 0 - VCC V VCELL Battery voltage potential 0 - VCC V ICC Supply current - 2 4 mA Outputs unloaded DSEL tri-state open detection -2 - Note 2 IGSEL tri-state open detection -2 IIZ VIH VIL VOH VOL IOH IOL IIL IIH IL Notes: Logic input high Logic input low VCC-1.
PAGE 13
bq2031 Impedance Symbol Parameter Minimum Typical Maximum Unit Notes RBATZ BAT pin input impedance 50 - - MΩ RSNSZ SNS pin input impedance 50 - - MΩ RTSZ TS pin input impedance 50 - - MΩ RPROG1 Soft-programmed pull-up or pull-down resistor value (for programming) - - 10 kΩ DSEL, TSEL, and QSEL RPROG2 Pull-up or pull-down resistor value - - 3 kΩ IGSEL RMTO Charge timer resistor 20 - 480 kΩ Timing (TA = TOPR; VCC = 5V ± 10%) Symbol Parameter Minimum Typical M
PAGE 14
bq2031 16-Pin DIP Narrow (PN) 16-Pin PN (0.300" DIP) Inches Dimension Millimeters Min. Max. Min. Max. A 0.160 0.180 4.06 4.57 A1 0.015 0.040 0.38 1.02 B 0.015 0.022 0.38 0.56 B1 0.055 0.065 1.40 1.65 C 0.008 0.013 0.20 0.33 D 0.740 0.770 18.80 19.56 E 0.300 0.325 7.62 8.26 E1 0.230 0.280 5.84 7.11 e 0.300 0.370 7.62 9.40 G 0.090 0.110 2.29 2.79 L 0.115 0.150 2.92 3.81 S 0.020 0.040 0.51 1.02 16-Pin SOIC Narrow (SN) 16-Pin SN (0.
PAGE 15
bq2031 Data Sheet Revision History Change No. Page No.
PAGE 16
PACKAGE OPTION ADDENDUM www.ti.
PAGE 17
PACKAGE MATERIALS INFORMATION www.ti.com 29-Jul-2008 TAPE AND REEL INFORMATION *All dimensions are nominal Device BQ2031SN-A5TR Package Package Pins Type Drawing SOIC D 16 SPQ Reel Reel Diameter Width (mm) W1 (mm) 2500 330.0 16.4 Pack Materials-Page 1 A0 (mm) B0 (mm) K0 (mm) P1 (mm) 6.5 10.3 2.1 8.0 W Pin1 (mm) Quadrant 16.
PAGE 18
PACKAGE MATERIALS INFORMATION www.ti.com 29-Jul-2008 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) BQ2031SN-A5TR SOIC D 16 2500 346.0 346.0 33.
PAGE 19
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.