BQ40Z50-R2 Datasheet, PDF (32/51 Pages) Texas Instruments – 1-Series, 2-Series, 3-Series, and 4-Series Li-Ion Battery Pack Manager

bq40z50-R2
SLUSCS4 – JUNE 2017
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Figure 26. Differential Filter
9.2.2.2.2 Power Supply Decoupling and PBI
The bq40z50-R2 device has an internal LDO that is internally compensated and does not require an external
decoupling capacitor.
The PBI pin is used as a power supply backup input pin providing power during brief transient power outages. A
standard 2.2-µF ceramic capacitor is connected from the PBI pin to ground, as shown in Figure 27.
C13
2.2 μF
1 _PBI
2 _VC4
3 _VC3
4 _VC2
5 VC1
6 _SRN
7 NC
8 _SRP
24
PTCEN
PTC ²³
LEDCNTLC ²²
LEDCNTLB ²¹
LEDCNTLA ²⁰
SMBC ¹⁹
SMBD ¹⁸
DISP ¹⁷
Copyright © 2017 , Texas Instruments Incorporated
Figure 27. Power Supply Decoupling
9.2.2.2.3 System Present
The System Present signal informs the gas gauge whether the pack is installed into or removed from the system.
In the host system, this pin is grounded. The PRES pin of the bq40z50-R2 device is occasionally sampled to test
for system present. To save power, an internal pullup is provided by the gas gauge during a brief 4-μs sampling
pulse once per second. A resistor can be used to pull the signal low and the resistance must be 20 kΩ or lower
to ensure that the test pulse is lower than the VIL limit. The pullup current source is typically 10 µA to 20 µA.
32
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