bq26221

SLUS607 − MAY 2004

6

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FUNCTIONAL BLOCK DIAGRAM

UDG−02050

RBI

GPIO

VCC

SRP

VSS

SRN

HDQ

BAT

Multiplexer

Temperature

Sensor

Autocalibrating

VFC

Bandgap,

Reference and

Bias

ADC

RAM

Temperature

Compensated

Precision

Oscillator

Timer

System I/O

and Control

User

Registers

Flash

ID

TERMINAL FUNCTIONS

TERMINAL

I/O

DESCRIPTION

NAME

No.

I/O

DESCRIPTION

BAT

5

I

Battery voltage sense input. This pin is used for sensing and measuring the battery voltage.

RBI

1

I

Register backup input. The RBI input pin is used with a storage capacitor or external supply to

provide backup potential to the internal RAM and registers while VCC is < V(POR).

GPIO

8

I/O

General-purpose input/output pin. GPIO is a general-purpose programmable input or output port

whose state is controlled via the HDQ serial communications interface.

HDQ

4

I/O

Single-wire HDQ interface. HDQ is a single-wire serial communications interface port. This

bidirectional input/output communicates the register information to the host.

SRN

6

I

Current sense input 2. The bq26221 interprets charge and discharge activity by monitoring and

integrating the voltage drop, VSR, across pins SRP and SRN. The SRN input connects to the

sense resistor and the negative terminal of the pack. VSRP < VSRN indicates discharge, and

VSRP > VSRN indicates charge.

SRP

7

I

Current sense input 1. The bq26221 interprets charge and discharge activity by monitoring and

integrating the voltage drop, VSR, across pins SRP and SRN. The SRP input connects to the

sense resistor and the negative terminal of the battery. VSRP < VSRN indicates discharge, and

VSRP > VSRN indicates charge.

VCC

2

I

Supply voltage

VSS

3

−

Ground