DS1881
Dual NV Audio Taper Digital Potentiometer
8 _____________________________________________________________________
Detailed Description
The DS1881 is a dual-channel, digitally controlled,
audio potentiometer. The Block Diagram illustrates the
features of the DS1881. The following sections discuss
these features in detail.
Potentiometer Configurations
The DS1881 potentiometers have two possible attenua-
tion configuration options. The Configuration Register
section discusses how to change between the two
options. Note that both potentiometers are always set to
the same option.
The factory default for both potentiometers is Option 1
(see Table 1). Option 1 provides 64 positions with 1dB
attenuation per step for positions 0 through 62 and
mute as position 63. Option 2 (see Table 2) is a 34-
position configuration. From position 0, the first 12
steps have 1dB attenuation per step, the next 12 have
2dB attenuation per step, and the following 8 steps
have 3dB attenuation per step. The last position, posi-
tion 33, is the mute setting.
Zero-Crossing Detection
Zero-crossing detection is a user-selectable feature
used to help eliminate clicking or popping noises dur-
ing changes of potentiometer settings. See the
Configuration Register section to learn how to enable
the zero-crossing detection feature.
After the I
2
C master issues a command to change the
wiper position and the DS1881 has responded with an
acknowledge (ACK) to the command, the DS1881 has
a 50ms window to change the wiper position. The
DS1881 constantly monitors the voltage of the high and
low terminals of both potentiometers. During the 50ms
window, if the zero-crossing detection is enabled, then
each potentiometer’s wiper will change position if the
high and low terminals of the same potentiometer
become equal in potential (i.e., the magnitude of the
input signal is zero). If a zero-crossing event does not
occur within the 50ms window, then the wiper is
allowed to change to the new position regardless of the
state of the input signal. When the zero-crossing detec-
tion feature is not enabled, the DS1881 will allow wiper
movement as soon as the DS1881 has issued the
acknowledge to the master-controlling device.
Table 1. Configuration Option 1
