V

REG

R

NTC

NTC

ADx

Figure 8-1. External Thermistor Biasing

8.3.9 Power Supply Control

The BQ28Z610-R1 device manages its supply voltage dynamically according to operating conditions. When

VVC2 > VSWITCHOVER– + VHYS, the AFE connects an internal switch to BAT and uses this pin to supply power to

its internal 1.8-V LDO, which subsequently powers all device logic and flash operations. Once VC2 decreases

to VVC2 < VSWITCHOVER–, the AFE disconnects its internal switch from VC2 and connects another switch to

PACK, allowing sourcing of power from a charger (if present). An external capacitor connected to PBI provides

a momentary supply voltage to help guard against system brownouts due to transient short-circuit or overload

events that pull VC2 below VSWITCHOVER–.

8.3.10 Power-On Reset

In the event of a power-cycle, the BQ28Z610-R1 AFE holds its internal RESET output pin high for tRST duration

to allow its internal 1.8-V LDO and LFO to stabilize before running the AGG. The AFE enters power-on reset

when the voltage at VREG falls below VREGIT– and exits reset when VREG rises above VREGIT– + VHYS for tRST

time. After tRST, the BQ28Z610-R1 AGG will write its trim values to the AFE.

normal operation

(untrimmed)

normal operation

(trimmed)

1.8-V Regulator

LFO

tOSU

tRST

AFE RESET

VIT+

VIT–

AGG writes trim values to

AFE

Figure 8-2. POR Timing Diagram

8.3.11 Bus Communication Interface

The BQ28Z610-R1 device has an I2C bus communication interface. This device has the option to broadcast

information to a smart charger to provide key information to adjust the charging current and charging voltage

based on the temperature or individual cell voltages.

BQ28Z610-R1

SLUSE07B – JANUARY 2020 – REVISED JANUARY 2022

www.ti.com

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