BQ24085 Datasheet, PDF(13/34 Page) Texas Instruments – 750 mA SINGLE-CHIP Li-Ion/Li-Pol CHARGE MANAGEMENT IC WITH THERMAL REGULATION

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bq24085, bq24086

bq24087, bq24088

www.ti.com .................................................................................................................................................... SLUS784B â DECEMBER 2007 â REVISED MAY 2008

Sleep Mode

The bq24085/6/7/8 enters the sleep mode when the input power voltage (IN) is above the power down threshold

V(PDWN) but still lower than the input power detection threshold, V(IN) < V(OUT) + VIN(DT).

During the sleep mode the charger is off, and the host commands at the control pins are not interpreted. The

integrated power mosfet connected between IN and OUT pins is off, the status output pins STAT1 and STAT2

are set to the high impedance state and the PG output indicates input power not detected.

The sleep mode is entered from any other state, if the input power (IN) is not detected.

Overvoltage Lockout

The input power is detected when the input voltage V(IN) > V(OUT) + VIN(DT). When the input power is detected

the bq24085/6/7/8 transitions from the sleep mode to the power-on-reset mode. In this mode of operation, an

internal timer T(POR) is started and internal blocks are reset (power-on-reset). Until the timer expires, the STAT1

and STAT2 outputs indicate charger OFF, and the PG output indicates the input power status as not detected.

At the end of the power-on-reset delay, the internal comparators are enabled, and the STAT1, STAT2 and PG

pins are active.

Stand-By Mode

In the bq24085/6/7/8, the stand-by mode is started at the end of the power-on-reset phase, if the input power is

detected and CE = HI. In the stand-by mode, selected blocks in the IC are operational, and the control logic

monitors system status and control pins to define if the charger will set to on or off mode. The quiescent current

required in stand-by mode is 100 ÂµA typical.

If the CE pin is not available the bq24085/6/7/8 enters the begin charge mode at the end of the power-on-reset

phase.

Begin Charge Mode

All blocks in the IC are powered up, and the bq24085/6/7/8 is ready to start charging the battery pack. A new

charge cycle is started when the control logic decides that all conditions required to enable a new charge cycle

are met. During the begin charge phase all timers are reset, after that the IC enters the charging mode.

Charging Mode

When the charging mode is active, the bq24085/6/7/8 executes the charging algorithm, as described in the

operational flow chart, Figure 14.

Suspend Mode

The suspend mode is entered when the pack temperature is not within the valid temperature range. During the

suspend mode the charger is set to off, but the timers are not reset.

The normal charging mode resumes when the pack temperature is within range.

LDO Mode Operation

The LDO Mode (TMR pin open circuit) disables the charging termination circuit, disables the battery detect

routine and holds the safety timer clock in reset. This is often used for operation without a battery or in

production testing. This mode is different than a typical LDO since it has different modes of operation, and

delivers less current at lower output voltages. See Figure 20 for the output current versus the output voltage.

Note that a load on the output prior to powering the device may keep the part in short-circuit mode. Also, during

normal operation, exceeding the programmed fast charge level causes the output to drop, further restricting the

output power, and soon ends up in short-circuit mode. Operation with a battery or keeping the average load

current below the programmed current level prevents this type of latch up. The out pin current can be monitored

via the ISET pin. If in LDO mode without a battery present, It is recommended that a 350-â¦ feedback resistor be

used between the BAT and OUT pins.

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Product Folder Link(s): bq24085, bq24086 bq24087, bq24088

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