SA2159

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

Rev: 1.0

2005.04.22

Http: www.silan.com.cn

Page 3 of 11

PIN CONFIGURATION

PIN DESCRIPTION

Pin No.

Symbol

Description

1

IN

Signal input

2

EC+

Positive exponential control

3

EC-

Negative exponential control

4

EC+(SYM)

Symmetry control

5

V-

Negative power

6

GND

Ground

7

V+

Positive power

8

OUT

Output

FUNCTION DESCRIPTION

OPERATING THEORY

The SA2159 VCA is designed for high performance in audio frequency applications which requires exponential

gain control, low distortion, wide dynamic range and low DC bias modulation. The gain control part controls gain

by converting an input current signal to a bipolar logged voltage, adding a DC control voltage and reconverting

the summed voltage back to a current through a bipolar antilog circuit.

The simplified internal circuit diagram of the IC is shown in figure 1. The AC input signal current flows in the

input pin 1, which is maintained at a virtual ground potential by the internal op amp.

Figure 1. Simplified internal circuit diagram