BQ24030 Datasheet, PDF(15/20 Page) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINYI)

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BQ24030 Datasheet, PDF (15/20 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINYI)

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bq24030, bq24032, bq24035

www.ti.com

SLUS618 â AUGUST 2004

Charge Timer Operation

As a safety backup, the bqTINY-III monitors the charge time in the charge mode. If taper threshold is not

detected within the time period, t(CHG), the bqTINY-III turns off the charger and enunciates FAULT on the STAT1

and STAT2 pins. The resistor connected between the TMR and VSS, RTMR, determines the timer period. The

K(TMR) parameter is specified in the specifications table. In order to disable the charge timer, eliminate RTMR,

connect the TMR pin directly to the LDO pin. Note that this action eliminates all safety timers also clears any

timer fault. TMR pin should not be left floating.

t(CHG) + K(TMR) R(TMR)

(5)

While in the thermal regulation mode or DPPM mode, the bqTINY-III dynamically adjusts the timer period in order

to provide the additional time needed to fully charge the battery. This proprietary feature is designed to prevent

against early or false termination. The maximum charge time in this mode, t(CHG-TREG), is calculated by the

equation Equation 6.

t (CHG*TREG)

t(CHG) V(SET)

V(SET*REG)

(6)

Note that since this adjustment is dynamic and changes as the ambient temperature changes and the charge

level changes, the timer clock is adjusted. It is difficult to estimate a total safety time without integrating the

above equation over the charge cycle. Therefore, understanding the theory that the safety time is adjusted

inversely proportionately with the charge current and the battery is a current-hour rating the safety time

dynamically adjusts appropriately.

The V(SET) parameter is specified in the specifications table. V(SET-TREG) is the voltage on the ISET pin during the

thermal regulation mode and is a function of charge current. (Note that charge current is dynamically adjusted

during the thermal regulation mode).

V(SET*TREG)

I(OUT) R(SET)

K(SET)

(7)

Charge Taper Detection, Termination and Recharge

The bqTINY-III monitors the charging current during the voltage regulation phase. Once the taper threshold,

I(TAPER), is detected the bqTINY-III terminates charge. The resistor connected between the ISET1 and VSS, RSET,

determines the taper detection level. The V(TAPER) and K(SET)parameters are specified in the specifications table.

Note that this applies to both AC and USB charging.

I (TAPER)

V(TAPER)

RSET

K(SET)

(8)

After charge termination, the bqTINY-III re-starts the charge once the voltage on the OUT pin falls below the

V(RCH) threshold. This feature keeps the battery at full capacity at all times. Please see the Battery Absent

Detection section for additional details.

LDO Register

The bqTINY-III provides a 3.3V LDO regulator. This regulator is typically used to power USB transceiver or

drivers in portable applications. Note that this LDO is only enabled when either AC or USB inputs are present.

Sleep and Standby Modes

The bqTINY-III charger circuitry enters the low-power sleep mode if both AC and USB are removed from the

circuit. This feature prevents draining the battery into the bqTINY-III during the absence of input supplies. Note

that in SLEEP mode, Q2 remains on (i.e. battery connected to the OUT pin) in order for the battery to continue

supplying power to the system.

The bqTINY-III enters the low-power standby mode if while AC or USB is present, the CE input is low. In this

suspend mode, internal PowerFETs Q1 and Q3 (refer to block diagram) are turned off, the BAT input is used to

power the system through OUT pin and the LDO remains on (powered from output). This feature is designed to

limit the power drawn from the input supplies (such as USB suspend mode).

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