BQ2007 datasheet(3/16 Pages) TI

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COM

Common LCD/LED output

Common

output

for

LCD/LED

display

SEGA—G. Output is high-impedance during

initialization

allow

reading

soft-programmed

inputs

DSEL1, DSEL2,

MSEL, MULT, and QDSEL.

ALARM

Audio output

Audio alarm output.

Timer mode select

TM is a three-level input that controls the set-

tings for charge control functions. See Table 5.

VSEL

Voltage termination select

This

input

switches

the

voltage

detect

sensitivity. See Table 5.

FAST

Fast charge rate select

The FAST input switches between Fast and

Standard charge rates. See Table 4.

DCMD

Discharge command

The DCMD input controls the discharge-

before-charge function. A negative-going

pulse initiates a discharge action. If DCMD

is connected to VSS, automatic discharge-

before-charge is enabled. See Figure 3.

TCO

Temperature cut-off threshold input

Minimum allowable battery temperature-

sensor voltage. If the potential between TS

and SNS is less than the voltage at the TCO

input, then any fast charging or top-off

charging is terminated.

SNS

Sense resistor input

SNS controls the switching of MOD output based

on an external sense resistor. This provides the

lower reference potential for the BAT pin and the

TS pin.

BAT

Battery voltage input

Battery voltage sense input referenced to SNS

for the battery pack being charged. This resis-

tor divider network is connected between the

positive and the negative terminals of the

battery. See Figure 1.

Temperature sense input

Input referenced to SNS for battery tem-

perature monitoring negative temperature

coefficient (NTC) thermistor.

DIS

Discharge control

DIS is a push-pull output that controls an

external transistor to discharge the battery

before charging.

VSS

Ground

VCC

VCC supply input

MOD

Current-switching control output

Push/pull output that controls the charging

current to the battery. MOD switches high to

enable current flow and low to inhibit current

flow.

Functional Description

Figure 1 illustrates charge control and display status

during a bq2007 charge cycle. Table 1 summarizes the

bq2007 operational features. The charge action states

and control outputs are given for possible input

conditions.

Charge Action Control

The bq2007 charge action is controlled by input pins

DCMD, VSEL, FAST, and TM. When charge action is

initiated, the bq2007 enters the charge-pending state,

checks for acceptable battery voltage and temperature,

and performs any required discharge-before-charge

operations. DCMD controls the discharge-before-charge

function, and VSEL, FAST, and TM select the charger

configuration. See Tables 4 and 5.

During charging, the bq2007 continuously tests for

charge termination conditions: negative delta voltage,

peak voltage detection, maximum time-out, battery

over-voltage, and high-temperature cutoff. When the

charge state is terminated, a trickle charge continues to

compensate for self-discharge and maintain the fully

charged condition.

Charge Status Indication

Table 2 summarizes the bq2007 charge status display

indications. The charge status indicators include the

DIS output, which can be used to indicate the discharge

state, the audio ALARM output, which indicates charge

completion and fault conditions, and the dedicated

status outputs, LED1 and LED2.

bq2007

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