SA572 Datasheet, PDF (8/12 Pages) NXP Semiconductors – Programmable analog compandor

Philips Semiconductors
Programmable analog compandor
Product specification
SA572
R4
+VB
R3
17.3k
C_IN1
V_IN
2.2µF
–
A1
+
R5
100k
C_IN2
R1
(7,9) _6.8k
C_IN3
2.2µF
(5,11)
∆G
V_REF
BUFFER
(6,10) R6
1k
(2,14)
(4,12)
A2
C1
2.2µF
R2
3.3k
(3,13)
CA CR
1µF 10µF
V_OUT
(8)
(16)
+V_CC
Figure 7. Basic Expandor Schematic
SR00700
Basic Compressor
Figure 8 shows the hook-up of the circuit as a compressor. The IC is
put in the feedback loop of the OPA A₁. The system gain expression
is as follows:
ǒ Ǔ ^VOUT
V_IN
+
1
I₁
2
@
R₂ @ R₁
R₃ @ V_IN(AVG)
2
(7)
R_DC1, R_DC2, and CDC form a DC feedback for A₁. The output DC
level of A₁ is given by
ǒ Ǔ V_ODC
+ V_REF
1
)
R_DC1
)
R₄
R_DC2
(8)
ǒ Ǔ * V_B @
R_DC1 ) R_DC2
R₄
The zener diodes D₁ and D₂ are used for channel overload
protection.
R4
RDC1
RDC2
9.1k
C2 .1µF
9.1k
CDC
10µF
C_IN1
V_IN ^2.2µF
R3
17.3k
C1
–
A1
+
D1
D2
1k R5
(6,10) _VREF
V_OUT
(5,11)
(2,14)
(4,12)
R1 (7,9)
∆G
6.8k
C_IN2
2.2µF
BUFFER
C_IN3
2.2µF
CR CA
10µF 1µF
3.3k
R2
(3,13)
(8)
V_CC ⁽¹⁶⁾
Figure 8. Basic Compressor Schematic
SR00701
1998 Nov 03
8