ACS422A68TAGZBX8 IDT, ACS422A68TAGZBX8 Datasheet - Page 51

• Manufacturer Part Number: ACS422A68TAGZBX8
• Description: Interface - CODECs
• Manufacturer: IDT

Specifications of ACS422A68TAGZBX8

• Rohs: yes
• Part # Aliases: IDTACS422A68TAGZBX8

ACS422x68
LOW-POWER, HIGH-FIDELITY, INTEGRATED CODEC
©2011 INTEGRATED DEVICE TECHNOLOGY, INC.
4.3.
The MICBIAS output is used to bias electric type microphones. It provides a low noise reference voltage used for an
external resistor biasing network. The MICB control bit is used to enable the output.
The MICBIAS can source up to 3mA of current; therefore, the external resistors must be large enough to conform to
this limit.
4.4.
The Programmable Gain Amplifier (PGA) enables the input signal level to be matched to the ADC input range. Ampli-
fier gain is adjustable across the range +30dB to –17.25dB (using 0.75dB steps). The PGA can be controlled directly by
the system software using the Input Volume Control registers (INVOLL and INVOLR), or alternately the Automatic
Level Control (ALC) function can automatically control the gain. If the ALC function is used, writing to the Input Volume
Control registers has no effect.
Left and right input gains are independently adjustable. By controlling the update bit (INVOLU), the left and right gain
settings can be simultaneously updated. To eliminate zipper noise, LZCEN and RZCEN bits enable a zero-cross detec-
tor to insure changes only occur when the signal is at zero. A time-out for zero-cross is also provided, using TOEN in
register R29 (1Dh).
Software can also mute the inputs in the analog domain.
R26 (1Ah)
Power Management
(1)
Register Address
Microphone Bias
4.3.1.
Programmable Gain Control
Microphone Bias Control Register
Internal Mic
Voltage
Bit
1
Table 59. Power Management 1 Register - Mic Bias Enable
Label
MICB
+
-
Figure 18. Mic Bias
Type
RW
AGND
Resistor
Resistor
Internal
Internal
Default
51
MICB
0
Microphone Bias Enable
0 = OFF (high impedance output)
1 = ON
MICBIAS 2.5V
Description
ACS422X68
V1.6 01/13