SHUTDOWN MODE
Charger detect on
TS2 pulldown detect on
NORMAL MODE
Monitoring on
Protection on
REG18,
REG1, REG2
on
SLEEP MODE
REG18,
REG1, REG2
on
Comparator protections on
Periodic ADC protections on
Current wake detector on
Charger
detection or TS2
pulldown
detection
Shutdown signal by
RST_SHUT pin or
command or low
V
BAT
or high temp
Shutdown signal by
RST_SHUT pin or
low V
BAT
or high
temp
Very low V
BAT
EXIT_DEEPSLEEP()
command or reset
signal by RST_SHUT pin or charger
detected
DEEPSLEEP()
command
twice, or
Permanent Fail
SLEEP_DISABLE()
command or fault or fault recovery
or
current detected
or
charger detected
or reset signal
by RST_SHUT pin
Low current
Reset signal by RST_SHUT
pin
Blue = programmable
DEEPSLEEP MODE
REG18,
REG1, REG2
on
LFO on
DEEPSLEEP()
command twice
Figure 13-1. Device Functional Modes
13.2 NORMAL Mode
NORMAL mode is the highest performance mode of the device, in which the device regularly measures voltage,
current, and temperature, the LFO (low frequency oscillator) is operating, and the internal processor powers
up (as needed) for data processing and control. Full battery protections operate based on device configuration
settings. System current is measured at intervals of 3 ms, with cell voltages measured at intervals of 45 ms
or slower, depending on configuration. The device also provides a configuration bit that causes the conversion
speed for both voltages and CC2 current to be doubled, with a reduction in measurement resolution.
The device is generally in NORMAL mode when any active charging or discharging is underway. When the
CC1
Current()
measurement falls below a programmable current threshold, the system is considered in relax mode,
and the BQ76942 device can autonomously transition into SLEEP mode, depending on configuration.
13.3 SLEEP Mode
SLEEP mode is a reduced functionality state that can be optionally used to reduce power dissipation when
there is little or no system load current or charging in progress, but still provides voltage at the battery pack
terminals to keep the system active. At initial powerup, a configuration bit determines whether the device can
enter SLEEP mode. After initialization, SLEEP mode can be allowed or disallowed using subcommands. Status
bits are provided to indicate whether the device is presently allowed to enter SLEEP mode or not, and whether it
is presently in SLEEP mode or not.
When the magnitude of the CC1 Current measurement falls below a programmable current threshold, the
system is considered in relax mode, and the BQ76942 device autonomously transitions into SLEEP mode,
if settings permit. During SLEEP mode, comparator-based protections operate the same as during NORMAL
mode. ADC-based current, voltage, and temperature measurements are taken at programmable intervals. All
temperature protections use the ADC measurements taken at these intervals, so they will update at a reduced
rate during SLEEP mode.
The BQ76942 device exits SLEEP mode if a protection fault occurs, current begins flowing, a charger is
attached, if forced by a subcommand, or if the RST_SHUT pin is asserted for < 1 s. When exiting based
on current flow, the device quickly enables the FETs (if the CHG FET was off or the DSG FET was in source-
SLUSE14B – DECEMBER 2020 – REVISED DECEMBER 2021
50
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