BQ2023 Datasheet, PDF (9/27 Pages) Texas Instruments – SINGLE-WIRE ADVANCED BATTERY MONITOR IC FOR CELLULAR AND PDA APPLICATIONS

bq2023
SINGLEĆWIRE ADVANCED BATTERY MONITOR IC
FOR CELLULAR AND PDA APPLICATIONS
SLUS480B – MAY 2001
APPLICATION INFORMATION
functional description (continued)
low-power sleep mode
In order to minimize power consumption, the bq2023 offers a low-power sleep mode. Table 2 shows the active
registers during normal and sleep modes.
Table 2. Operational States
MODE
Normal
Sleep
ACTIVE REGISTERS
CCE, DCR, CTC, DTC, SDR, TEMPH, TEMPL
SDR, TEMPH, TEMPL
There are two methods for entering the sleep mode.
sleep mode as a result of charge/discharge inactivity
The bq2023 enters sleep mode if battery current (i.e., voltage difference between the SRP and SRN pins) is
less than the WOE threshold, and the SLEN bit (in the MODE/WOE register) is set, and there is no
communication activity on the SDQ pin for approximately one hour. The bq2023 wakes on either a low to high
or high to low transition on the SDQ pin. The SLEN bit is set during power-on-reset. Table 2 shows the available
WOE thresholds.
Table 3. WOE Thresholds
WOE3–1
(HEX)
0h
1h
2h
3h
4h
5h
6h
7h^†
† _Default
VWOE
(µV)
N/A
21.35
18.30
15.25
12.20
9.15
6.10
3.05
sleep mode as a result of change PDET input
PDET input can also place the bq2023 in sleep mode. The bq2023 enters sleep mode in response to PDET input
going low. This happens regardless of the state of the SLEN bit (in the MODE/WOE register). In order to wake
up the bq2023, several conditions need to be considered:
D A low-to-high transition on PDET will wake the device, if
– SLEN = 0, or
– SLEN = 1 and the device was awake when PDET was pulled low.
– To ensure proper wake-up sequence it is recommended that the host initiate either a low to high or high
to low transition on the SDQ pin.
D A low-to-high transition will not wake the device if
– SLEN = 1 and the device was asleep when PDET was pulled low.
Note that PDET signal should be tied to the V_CC during a POR condition.
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