Datasheet

bq76PL536A
www.ti.com SLUSAD3A –JUNE 2011–REVISED AUGUST 2012
Auxiliary Power Output (AUX)
The bq76PL536A provides an approximately 1-mA auxiliary power output that is controlled via
IO_CONTROL[AUX]. This output is taken directly from REG50. The current drawn from this pin must be included
in the REG50 current-limit budget by the designer.
Undervoltage Lockout and Power-On Reset
The device incorporates two comparators to detect low V
BAT
conditions. The first detects low voltage where some
device digital operations are still available. The second, (POR) detects a voltage below which device operation is
not ensured.
UVLO
When the UVLO threshold voltage is sensed for a period ≥ UVLO
DELAY
, the device is no longer able to make
accurate analog measurements and conversions. The ADC, cell-balancing and fault-detection circuitry are
disabled. The digital circuitry, including host CPU and vertical communications between ICs, is fully functional.
Register contents are preserved with the exception that CB_CTRL is set to 0, and the UVLO bit is set in
DEVICE_STATUS[].
Power-On Reset (POR)
When the POR voltage threshold or lower is sensed for a period ≥ UVLO
DELAY
, the device is no longer able to
function reliably. The device is disabled, including all fault-detection circuitry, host SPI communications, vertical
communications, etc.
After the voltage rises above the hysteresis limit longer than the delay time, the device exits the reset state, with
all registers set to default conditions. The FAULT_STATUS[POR] bit is set and latched until reset by the host.
The device no longer has a valid address (DEVICE_ADDRESS[AR] = 0, ADDRESS_CONTROL[] = 0). The
device should be reprogrammed with a valid address, and any registers re-written if non-default values are
desired.
Reset Command
The bq76PL536Acan also be reset by writing the reset code (0xa5) to the RESET register. All devices respond to
a broadcast RESET command regardless of their current assigned address. The result is identical to a POR with
the exception that the normal POR period is reduced to several hundred microseconds.
Thermal Shutdown (TSD)
The bq76PL536Acontains an integrated thermal shutdown circuit whose sensor is located near the REG50 LDO
and has a threshold of T
SD
. When triggered, the REG50 regulator reduces its output voltage to zero, and the
ADC is turned off to conserve power. The thermal shutdown circuit has a built-in hysteresis that delays recovery
until the die has cooled slightly. When the thermal shutdown is active, the DEVICE_STATUS[TSD] bit is set. The
IO_CONTROL[SLEEP] and ALERT[SLEEP] bits also become set to reduce power consumption.
WARNING
The secondary protector settings are DISABLED in the TSD state.
CAUTION
Temperature measurement and monitoring do not function due to loss of power if the
thermistors are powered from the REG50 or AUX pins and TSD occurs. Protection-
dependent schemes implemented by the designer which depend on the REG50
voltage also may not function as a result of loss of the REG50 output.
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