BQ40Z50-R1 datasheet(33/55 Pages) TI1

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bq40z50-R1

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SLUSCB3 – JULY 2015

Figure 26. Differential Filter

9.2.2.2.2

Power Supply Decoupling and PBI

The bq40z50-R1 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.

Figure 27. Power Supply Decoupling

9.2.2.2.3

System Present

The System Present signal is used to inform 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-R1 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 k

or lower to insure that the test pulse is lower than the VIL limit. The pull-up current source is typically 10 µA to

20 µA.

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BQ40Z50-R1 数据表(PDF) 33 Page - Texas Instruments