3-111

TELCOM SEMICONDUCTOR, INC.

7

6

5

4

3

1

2

8

TC7109A

B9–B12

POL, OR

B1-B8

LBEN

HBEN

8

6

ANALOG

IN

RUN/HOLD

SEND

MODE CE/

LOAD

+5V

TC7109A

B9–B12

POL, OR

B1–B8

LBEN

HBEN

8

6

8-BIT DATA BUS

ANALOG

IN

RUN/HOLD

SEND

MODE CE/

LOAD

+5V

TC7109A

B9–B12

POL, OR

B1–B8

LBEN

HBEN

8

6

ANALOG

IN

RUN/HOLD

SEND

MODE CE/

LOAD

+5V

TBRL DRR

GND

TBRE

RBR1–RBR8

SFD

TBR1–TBR8

SERIAL OUTPUT

SERIAL INPUT

6402 CMOS UART

23

Figure 21.

Handshake Interface for Multiplexed Converters

Integrating Converter Features

The output of integrating ADCs represents the integral,

or average, of an input voltage over a fixed period of time.

Compared with techniques in which the input is sampled and

held, the integrating converter averages the effects of noise.

A second important characteristic is that time is used to

quantize the answer, resulting in extremely small nonlinearity

errors and no missing output codes. The integrating con-

verter also has very good rejection of frequencies whose

periods are an integral multiple of the measurement period.

This feature can be used to advantage in reducing line

frequency noise (Figure 22).

30

20

10

0

0.1/t

1/t

10/t

INPUT FREQUENCY

t = MEASUREMENT

PERIOD

Figure 22. Normal Mode Rejection of Dual-Slope Converter as a

Function of Frequency

TC7109

TC7109A

12-BIT

ANALOG-TO-DIGITAL CONVERTERS