AD5293BRUZ-20 Analog Devices Inc, AD5293BRUZ-20 Datasheet - Page 23

• Manufacturer Part Number: AD5293BRUZ-20
• Description: IC DGTL POT 1024POS 20K 14TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD5293BRUZ-20

• Temperature Coefficient: 35 ppm/°C Typical
• Taps: 1024
• Resistance (ohms): 20K
• Number Of Circuits: 1
• Interface: SPI Serial
• Voltage - Supply: 9 V ~ 33 V, ±9 V ~ 16.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 14-TSSOP
• Resistance In Ohms: 20K
• End To End Resistance: 20kohm
• Track Taper: Linear
• No. Of Steps: 256
• Resistance Tolerance: ± 1%
• Control Interface: Serial, SPI
• No. Of Pots: Single
• Potentiometer Ic: RoHS Compliant
• Supply Voltage Range: ± 9V To ± 16.5V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Type: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AD5293BRUZ-20-U1; AD5293BRUZ-20-U1

AUDIO VOLUME CONTROL
The excellent THD performance and high voltage capability
of the AD5293 make it ideal for digital volume control. The
AD5293 is used as an audio attenuator; it can be connected
directly to a gain amplifier. A large step change in the volume
level at any arbitrary time can lead to an abrupt discontinuity of
the audio signal, causing an audible zipper noise. To prevent this,
a zero-crossing window detector can be inserted to the CS line to
delay the device update until the audio signal crosses the window.
Because the input signal can operate on top of any dc level,
rather than absolute 0 V level, zero crossing in this case means
the signal is ac-coupled, and the dc offset level is the signal zero
reference point.
The configuration to reduce zipper noise is shown in Figure 56,
and the results of using this configuration are shown in Figure 55.
V
IN
1µF
C1
R
90kΩ
R
10kΩ
4
5
U6
AD8541
5V
V+
V–
100kΩ
200Ω
Figure 56. Audio Volume Control with Zipper Noise Reduction.
R
R
1
2
R
100kΩ
5V
3
ADCMP371
ADCMP371
GND
GND
V
V
+5V
+5V
CC
CC
U2
U3
Rev. D | Page 23 of 24
SYNC
4
5
U4B
7408
6
1
2
U4A
The input is ac-coupled by C1 and attenuated down before
feeding into the window comparator formed by U2, U3, and U4B.
U6 is used to establish the signal as zero reference. The upper
limit of the comparator is set above its offset and, therefore, the
output pulses high whenever the input falls between 2.502 V
and 2.497 V (or 0.005 V window) in this example. This output
is AND’ e d with the chip select signal such that the AD5293
updates whenever the signal crosses the window. To avoid a
constant update of the device, the chip select signal should be
programmed as two pulses, rather than as one.
In Figure 55, the lower trace shows that the volume level changes
from a quarter-scale to full-scale when a signal change occurs
near the zero-crossing window.
7408
SCLK
+15V
0.1µF
0.1µF
SDIN
–15V
C3
C2
1
2
CHANNEL 1
FREQ = 20.25kHz
1.03V p-p
U1
V
V
SYNC
SCLK
SDIN
DD
SS
A
B
AD5293
20kΩ
Figure 55. Zipper Noise Detector
W
GND
–15V
+15V
V–
V+
U5
V
OUT
AD5293