AD7528
DIGITALLY CONTROLLED DUAL TELEPHONE
ATTENUATOR
In this configuration the AD7528 functions as a 2-channel digi-
tally controlled attenuator. Ideal for stereo audio and telephone
signal level control applications. Table IV gives input codes vs.
attenuation for a 0 dB to 15.5 dB range.
Table IV. Attenuation vs. DAC A, DAC B Code for the Circuit
of Figure 15
Attn. DAC Input
Code In Attn. DAC Input
Decimal dB Code
Code In
Decimal
dB
Code
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
1 1 1 1 1 1 1 1
1 1 1 1 0 0 1 0
1 1 1 0 0 1 0 0
1 1 0 1 0 1 1 1
1 1 0 0 1 0 1 1
1 1 0 0 0 0 0 0
1 0 1 1 0 1 0 1
1 0 1 0 1 0 1 1
1 0 1 0 0 0 1 0
1 0 0 1 1 0 0 0
1 0 0 1 0 0 0 0
1 0 0 0 1 0 0 0
1 0 0 0 0 0 0 0
0 1 1 1 1 0 0 1
0 1 1 1 0 0 1 0
0 1 1 0 1 1 0 0
255
242
228
215
203
192
181
171
162
152
144
136
128
121
114
108
88.0 0 1 1 0 0 1 1 0
88.5 0 1 1 0 0 0 0 0
89.0 0 1 0 1 1 0 1 1
89.5 0 1 0 1 0 1 1 0
10.0 0 1 0 1 0 0 0 1
10.5 0 1 0 0 1 1 0 0
11.0 0 1 0 0 1 0 0 0
11.5 0 1 0 0 0 1 0 0
12.0 0 1 0 0 0 0 0 0
12.5 0 0 1 1 1 1 0 1
13.0 0 0 1 1 1 0 0 1
13.5 0 0 1 1 0 1 1 0
14.0 0 0 1 1 0 0 1 1
14.5 0 0 1 1 0 0 0 0
15.0 0 0 1 0 1 1 1 0
15.5 0 0 1 0 1 0 1 1
102
96
91
86
81
76
72
68
64
61
57
54
51
48
46
43
Attenuation, dB
−
Input Code = 256 ϫ 10 exp
20
V
DD
V
A
IN
DAC A
A1
V
A
OUT
DB0
DB7
DATA BUS
CS
WR
DAC A/DAC B
AD7528
V
B
IN
DAC B
A2
V
B
OUT
SUGGESTED
OP AMP: AD644
For further applications information the reader is referred to
Analog Devices Application Note on the AD7528.
Figure 15. Digitally Controlled Dual Telephone Attenuator
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
20-Lead Cerdip (Q-20)
20-Lead Plastic DIP (N-20)
11
1.07 (27.18) MAX
20
1
0.28 (7.11)
20
11
PIN 1
0.255 (6.477)
0.24 (6.1)
10
0.245 (6.223)
10
1
0.32 (8.128)
0.30 (7.62)
0.32 (8.128)
0.29 (7.366)
0.97 (24.64)
0.935 (23.75)
0.14 (3.56)
PIN 1
0.135 (3.429)
0.125 (3.17)
0.145 (3.683)
MIN
0.20 (5.0)
0.14 (3.56)
0.125 (3.17)
0.125 (3.175)
MIN
0.15 (3.8)
0.125 (3.18)
SEATING
PLANE
SEATING
PLANE
0.011 (0.28)
0.009 (0.23)
0.011 (0.28)
0.009 (0.23)
0.11 (2.79)
0.09 (2.28)
0.065 (1.66)
0.045 (1.15)
0.021 (0.533)
0.015 (0.381)
15؇
0؇
0.07 (1.78) 0.02 (0.5) 0.11 (2.79)
0.05 (1.27) 0.016 (0.41) 0.09 (2.28)
LEAD NO. 1 IDENTIFIED BY DOT OR NOTCH
15؇
0؇
LEAD NO. 1 IDENTIFIED BY DOT OR NOTCH
LEADS ARE SOLDER OR TIN-PLATED KOVAR OR ALLOY 42
LEADS ARE SOLDER OR TIN-PLATED KOVAR OR ALLOY 42
20-Lead SOIC (R-20)
20-Lead Plastic Leaded Chip Carrier (P-20A)
0.5118 (13.00)
0.4961 (12.60)
0.180 (4.47)
0.165 (4.19)
0.395 (10.02)
0.385 (9.78)
SQ
0.12 (3.05)
0.09 (2.29)
0.020 (0.51) MIN
20
11
10
0.356 (9.04)
0.350 (8.89)
SQ
19
0.2992 (7.60)
0.2914 (7.40)
0.048 (1.21)
0.042 (1.07)
3
0.021 (0.53)
0.013 (0.33)
PIN 1
IDENTIFIER
18
4
8
0.4193 (10.65)
0.3937 (10.00)
0.050
(1.27)
BSC
1
TOP VIEW
(PINS DOWN)
0.032 (0.81)
0.026 (0.66)
14
0.02
(0.51)
MAX
PIN 1
9
13
0.1043 (2.65)
0.0926 (2.35)
0.0291 (0.74)
0.0098 (0.25)
0.025 (0.64)
MIN
0.02 (0.51)
MAX
0.060 (1.53)
MIN
8؇
0؇
0.0500 0.0192 (0.49)
0.0118 (0.30)
0.0040 (0.10)
0.0500 (1.27)
0.0157 (0.40)
SEATING
PLANE
0.0125 (0.32)
0.0091 (0.23)
(1.27)
BSC
0.0138 (0.35)
–8–
REV. B
ADI [ ADI ]
