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BQ769142
SLUSE91A – SEPTEMBER 2020 – REVISED FEBRUARY 2021
Typically, a 10-kΩ resistor is connected between the PACK+ terminal and the LD pin. This resistance
should be understood when considering the load impedance. The load detect current is enabled for a
programmable time duration, then is disabled for another programmable time duration, with this
sequence repeating until the load is detected as removed or it times out.
12 Device Hardware Features
12.1 Voltage References
The BQ769142 device includes two voltage references, V
for most measurements except external thermistors. V
oscillators, and integrated coulomb counter ADC. The value of V
ADC's measurement of the REG18 LDO voltage while using V
12.2 ADC Multiplexer
The ADC multiplexer connects various signals to the voltage ADC, including the individual differential cell voltage
pins, the on-chip temperature sensor, the biased thermistor pins, the REG18 LDO voltage, the VSS pin voltage,
and internal dividers connected to the VC14, PACK, and LD pins.
12.3 LDOs
The BQ769142 device contains an integrated 1.8-V LDO (REG18) that provides a regulated 1.8 V supply
voltage for the device's internal circuitry and digital logic. This regulator uses an external capacitor connected to
the REG18 pin, and it should only be used for internal circuitry.
The device also integrates two separately programmable LDOs (REG1 and REG2) for external circuitry, such as
a host processor or external transceiver circuitry, which can be programmed to independent output voltages. The
REG1 and REG2 LDOs take their input from the REGIN pin, with this voltage either provided externally or
generated by an on-chip preregulator (referred to as REG0). The REG1 and REG2 LDOs can provide an output
current of up to 45 mA each.
12.3.1 Preregulator Control
The REG1 and REG2 LDOs take their input from the REGIN pin, which should be approximately 5.5 V. This
REGIN pin voltage can be supplied externally (such as by a separate DC/DC converter) or using the integrated
voltage preregulator (referring to as REG0), which drives the base of an external NPN BJT (using the BREG pin)
to provide the 5.5-V REGIN pin voltage. When the preregulator is used, special care should be taken to ensure
the device retains sufficient voltage on its BAT pin, per the specifications in Specifications.
The system designer should ensure the external BJT can tolerate the peak power that may be
dissipated in it under maximum load expected on REG1 and REG2. If the maximum stack voltage is
80 V, then the BJT has a collector-emitter voltage of approximately 75 V, thereby dissipating 6.75 W if
REG1 and REG2 are both used to support a 45 mA load.
There is a diode connection between the REGIN pin (anode) and the BAT pin (cathode), so the
voltage on REGIN should not exceed the voltage on BAT.
12.3.2 REG1 and REG2 LDO Controls
The REG1 and REG2 LDOs in the BQ769142 device are for customer use, and their output voltages can be
programmed independently to 1.8 V, 2.5 V, 3.0 V, 3.3 V, or 5.0 V. The REG1 and REG2 LDOs and the REG0
preregulator are disabled by default in the BQ769142 device. While in SHUTDOWN mode, the REG1 and REG2
pins have ≈10-MΩ resistances to VSS to discharge any output capacitance. While in other power modes, when
REG1 and REG2 are powered down, they are pulled to VSS with an internal resistance of ≈2.5 kΩ. If pullup
resistors for serial communications are connected to the REG1 voltage output, the REG1 voltage can be
overdriven from an external voltage supply on the manufacturing line to enable communications with the device.
44
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Note
and V
REF1
is used by the integrated 1.8 V LDO, internal
REF2
REF2
for diagnostic purposes.
REF1
Note
Product Folder Links:
BQ769142
, with V
used by the voltage ADC
REF2
REF1
can be measured indirectly by the voltage
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