±10

±8

±6

±4

±2

0

2

4

6

8

10

±20

0

20

40

60

80

Forced Temperature (ƒC)

C009

At ±2000mA

±14

±12

±10

±8

±6

±4

±2

0

2

4

6

±20

0

20

40

60

80

Forced Temperature (ƒC)

C007

21

BQ78350-R1A

www.ti.com

SLUSE05 – DECEMBER 2019

Product Folder Links: BQ78350-R1A

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Copyright © 2019, Texas Instruments Incorporated

Figure 13. Battery Discharge Current Error Reported

Through Current()

Figure 14. Battery Temperature (External) Error Reported

Through Temperature()

10 Power Supply Recommendations

The BQ78350-R1A device is powered directly from the 2.5-V REGOUT pin of the BQ769x0 companion AFE. An

input capacitor of 0.1 µF is required between VCC and VSS and should be placed as close to the BQ78350-R1A

device as possible.

To ensure correct power up of the BQ78350-R1A device, a 100-k resistor between MRST and VCC is also

required. See the Schematic for further details.

11 Layout

11.1 Layout Guidelines

11.1.1 Power Supply Decoupling Capacitor

Power supply decoupling from VCC to ground is important for optimal operation of the BQ78350-R1A device. To

keep the loop area small, place this capacitor next to the IC and use the shortest possible traces. A large-loop

area renders the capacitor useless and forms a small-loop antenna for noise pickup.

Ideally, the traces on each side of the capacitor must be the same length and run in the same direction to avoid

differential noise during ESD. If possible, place a via near the VSS pin to a ground plane layer.

Placement of the RBI capacitor is not as critical. It can be placed further away from the IC.

11.1.2 MRST Connection

The MRST pin controls the gas gauge reset state. The connections to this pin must be as short as possible to

avoid any incoming noise. Direct connection to VCC is possible if the reset functionality is not desired or

necessary.

If unwanted resets are found, one or more of the following solutions may be effective:

•

Add a 0.1-μF capacitor between MRST and ground.

•

Provide a 1-kΩ pullup resistor to VCC at MRST.

•

Surround the entire circuit with a ground pattern.

If a test point is added at MRST, it must be provided with a 10-kΩ series resistor.

11.1.3 Communication Line Protection Components

The 5.6-V Zener diodes, which protect the BQ78350-R1A communication pins from ESD, must be located as

close as possible to the pack connector. The grounded end of these Zener diodes must be returned to the

PACK(–) node, rather than to the low-current digital ground system. This way, ESD is diverted away from the

sensitive electronics as much as possible.