SC7001Q

(Continued)

PIN No.

Symbol

Description

63

D GND

Digital ground

64~72

F1~F9

Function input pin 1~9

73

CVD OUT

Voltage double output

74

CVD(-)

Voltage double capacitor connection (-)

75

CVD(+)

Voltage double capacitor connection(+)

76

OUT

Beep frequency output (4096Hz)

77

OSC OUT

X-tal connection (32.768KHz)

78

OSC IN

X-tal connection

79

BP2

Backplane 2 of LCD display

80

BP3

Backplane 3 of LCD display

FUNCTIONAL DESCRIPTION

1. SC7001Q INTEGRATING DUAL-SLOPE A/D CONVERTER

The SC7001Q consists of a low-speed A/D and a high-speed A/D conversion circuit.

Low-speed A/D conversion circuit

When an analog DC input signal under 320mV is applied, the low-speed conversion proceeds like a sequence

of AUTO ZERO (A.Z)

→INTEGRATION (INT) →DEINTEGRATION (DEINT) → AUTO ZERO. One conversion

takes 519.7ms is the voltage measurement mode.

The counter data of DEINTEGRATION interval is transferred to the LCD and the output value is determined.

High-speed A/D conversion circuit

Range selection and barograph display operate by the high-speed conversion which is like that of low-speed

A/D conversion. One conversion takes 80ms in the voltage measurement mode.

Waveform and block diagram of dual-slope A/D converter (Negative input)

Conversion time

Tim

Speed

T1

T2

T3

Conversion time

T1+T2+T3

Low-speed A/D

100ms

200ms

219.7ms(109.8ms)*

519.7ms(409.8ms)

High-speed A/D

40ms

20ms

20ms(10ms)

80ms(70ms)

* : The value of parenthesis is for current measurement mode.

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

REV:1.2

2007.12.26

Http: www.silan.com.cn

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