Functional Description

General Operation

The bq2052 determines battery capacity by monitoring

the amount of charge removed from a primary battery.

The bq2052 measures discharge currents and battery

voltage, monitors the battery for the low battery-voltage

thresholds, and compensates available capacity for tem-

perature and discharge rate. The bq2052 measures ca-

pacity by monitoring the voltage across a small-value se-

ries sense resistor between the negative battery termi-

nal and ground.

Figure 1 shows a typical battery pack application of the

bq2052 using the LED display capability as a

charge-state indicator.

The bq2052 displays capacity

with two, four, or five LEDs using the programmed full

count (PFC) as the battery’s “full” reference. The bq2052

has a push-button input for momentarily enabling the

LED display.

Measurements

The bq2052 uses a voltage-to-frequency converter (VFC)

for discharge measurement and an analog-to-digital con-

verter (ADC) for battery voltage measurement.

Discharge Counting

The VFC measures the discharge flow of the battery by

monitoring a small value sense resistor between the SR

“discharge” activity when the potential at the SR input,

time using an internal counter. The fundamental rate of

the counter is 3.125

µVh. The VFC measures signals up

to 0.5V in magnitude.

Digital Magnitude Filter

The bq2052 has a digital filter to eliminate discharge

counting below a set threshold. The minimum discharge

µV.

3

Preliminary

bq2052

FG205201.eps

PROG6

CP

HDQ

SEG5

SEG4

SEG3

SEG2

SEG1

VSS

DISP

SB

VCC

REF

bq2052

Gas Gauge IC

LCOM

SR

RBI

0.1

µF

Q1

ZVNL110A

R1

C1

100K

RS

RB1

RB2

Load

Indicates optional.

(6.0V nominal and should not exceed 6.5V).

Otherwise, R1, C1, and Q1 are needed for regulation of > 2 cells.

3. Programming resistors and ESD-protection diodes are not shown.

4. R-C on SR is required.

To

µC

H or L

5. A series diode is required on RBI if the bottom series cell is used as the backup source.

If the cell is used, the backup capacitor is not required, and the anode is connected to the

positive terminal of the cell.

1.

Notes:

Figure 1. Application Diagram—5-Segment LED Display

Not Recommended For New Designs