BQ29312_15 Datasheet, PDF (15/39 Pages) Texas Instruments – FOUR CELL LITHIUM-ION

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bq29312
SLUS546E – MARCH 2003 – REVISED MARCH 2005
FUNCTIONAL DESCRIPTION (continued)
The default-state of the CHG and DSG FET drive is off, when PMS = GND. A host can control the FET drive by
programming OUTPUT CTL (b3...b1) where b1 is used to control the discharge FET, b2 is used to control the
charge FET and b3 is used to control the ZVCHG FET. These controls are only valid when not in the initialized
state. The CHG drive FET can be powered by PACK and the DSG FET can be powered by BAT.
Precharge and 0 V Charging—Theory of Operation
The bq29312 supports both a charger that has a precharge mode and one that does not. The bq29312 also
supports charging even when the battery falls to 0 V. Detail is described in the application section.
SLEEP Control Input (SLEEP)
The SLEEP input is pulled-up internally to REG. When SLEEP is pulled to REG, the bq29312 enters the SLEEP
mode. The SLEEP mode disables all the FET outputs and the OL, SC and watchdog faults are also disabled.
The RAM configuration is still valid on exit of the SLEEP mode. The host can force the bq29312 into SLEEP
mode via register control also.
ITEM
I²C Read/Write
REG Output
External pin control:
CHG, DSG, ZVCHG, TOUT, OD
OC and SC protection:
SCD, SCC and OCD
CELL Translation
PACKOUT, VMEN
Cell Balancing:
CB[3:0]
Watchdog: WDDIS
Table 1. SLEEP Control Input
FUNCTION
Active
Active
SLEEP
I²C READ/WRITE
EXIT SLEEP
Disabled
Write is available,
but read is disabled
Last pre-sleep entry configuration is valid.(If change
configuration, latest write data is valid.)
Power Modes
The bq29312 has three power modes, Normal, Sleep, and Ship. The following table outlines the operational
functions during these power modes.
POWER
MODE
Normal
Sleep
Ship
TO ENTER POWER MODE
SLEEP = GND and
STATE CTL( b0) = 0 and
STATE CTL( b1) = 0
{SLEEP = REG (floating) or
STATE CTL( b0) = 1 } and
STATE CTL( b1) = 0
STATE CTL( b1) = 1
And supply at the PACK pin is
removed
Table 2. Power Modes
TO EXIT POWER
MODE
SLEEP = GND and
STATE CTL( b0) = 0
Supply voltage to PACK
MODE DESCRIPTION
The battery is in normal operation with protection, power
management and battery monitoring functions available and
operating.
The supply current of this mode varies as the host can enable
and disable various power management features.
All functions stop except LDO and I²C interface.
On entry to this mode, all registers are masked off keeping their
state.
The host controller can change the RAM registers via the I²C
interface, but reading data is disabled until exit of Sleep mode.
The bq29312 is completely shut down as in the sleep mode. In
addition the REG output is disabled, I²C interface is powered
down and memory is not valid.
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