Datasheet
DS4420
I
2
C Programmable-Gain Amplifier
for Audio Applications
6 _____________________________________________________________________
Detailed Description
The key features of the DS4420 are illustrated in the
Block Diagram
.
Controlling the DS4420
The DS4420 is controlled through the I
2
C serial inter-
face. Gain, mute, and standby settings all reside in one
control register located at memory address F8h (see
Figure 1). Writes to other memory addresses are invalid.
Programmable Gain
The gain is adjustable from -35dB to +25dB in 3dB
increments. The gain is determined by the five LSBs of
the control register as shown in Figure 1. Gain settings
greater than 14h are invalid.
Mute Mode
The DS4420 is placed in mute mode by setting the mute
bit located in the control register (see Figure 1). When in
this mode, the output of the amplifier is muted and is
independent of the gain setting. The input-to-output
attenuation is specified in the
Electrical Characteristics
table as A
MUTE
.
Standby Mode
Standby mode is entered by setting the standby control
bit (see Figure 1). Setting the standby control bit mutes
the output of the amplifier and places the DS4420 into a
low-current (I
STBY
) consumption state. Unlike mute
mode, however, standby mode is intended for use when
no input signal is present. While in standby mode, the
DS4420 maintains input and output common-mode bias
voltages. The device produces no audible clicks or
pops when entering or exiting the standby state. The
time required for the output to become active when
exiting standby mode is specified as t
PU
.
Pin Description
PIN NAME FUNCTION
1A2
2A1
3A0
Address Select Inputs—Determine I
2
C Slave Address. Device address is 1010A
2
A
1
A
0
.
4 SCL I
2
C Serial Clock—Input for I
2
C Clock
5 SDA I
2
C Serial Data—Input/Output for I
2
C Data
6V
CC
Digital Power-Supply Terminal
7 GND Ground
8 IN+
9 IN-
Differential Audio Input Signal
10 N.C. No Connection
11 AGND Analog Ground (Must be Connected to GND)
12 OUT-
13 OUT+
Differential Audio Output Signal
14 AV
CC
Analog Power Supply (Must be Connected to V
CC
)
EP EP Exposed Paddle. Connect to GND and AGND.
Block Diagram
DS4420
3dB
GAIN
STEPS
AV
CC
AGNDGND
V
CC
A2A1A0
SDA
SCL
IN+
IN-
OUT+
OUT-
I
2
C INTERFACE
-35dB
TO +25dB
GAIN