M61040FP

REJ03F0237-0200 Rev.2.00 Mar 18, 2008

Page 11 of 24

Block Diagram Description

(1) Battery voltage detection circuit

The M61040 battery voltage detection circuit is shown in figure 3.

This circuit is composed of switch, buffer amplifier, reference voltage section and logic circuit.

Microcomputer selects detecting voltage before logic circuit controls the connection of switches. This connection

decides which cell voltage (Vbat1, Vbat2, Vbat3, Vbat4) should be output from analog out pin. Besides offset

voltage can be output.

In power down mode, supply current in this block is close to zero because all switches are off.

Note: Regard 50

µs as the standard of settling time by voltage change in this block.

S22

S21

S11

S32

S31

S42

S41

S02

S01

Vat1

Vat2

Vat3

Vat4

Vref

GND

Switch Control

From Serial to Parallel

conversion circuit

Logic Circuit

To Multiplexer circuit

+

−

5

6

7

8

11

Figure 3 Battery Voltage Detection Circuit