MAX4061 MAXIM [Maxim Integrated Products], MAX4061 Datasheet - Page 11

• Manufacturer Part Number: MAX4061
• Description: Differential Microphone Preamplifiers with Internal Bias and Complete Shutdown
• Manufacturer: MAXIM [Maxim Integrated Products]

The MAX4061/MAX4062 have a lower bias voltage and
low-impedance outputs (optimum electret bias resistor
can then be set externally). This gives a low-noise, flexi-
ble solution that can run from 2.4V to 5.5V, suitable for
hand-held devices such as PDAs that typically have
audio power supplies in the 3V region (see Figure 3).
In applications where the differential microphone is
placed some distance from the MAX4060/MAX4061/
MAX4062, using a remote differential bias scheme as
shown in Figure 4 can provide improved noise rejection.
The output voltage has a DC-bias voltage independent
of the power supplies, resulting in superior PSRR per-
formance. The MAX4061 output is high impedance
when the part is in shutdown mode. AC-coupling the
output into the next audio stage (e.g., CODEC) is rec-
ommended.
Figure 2. MAX4060 Used for Biasing a Microphone
Differential Microphone Preamplifiers with
______________________________________________________________________________________
MICROPHONE
INPUT
Internal Bias and Complete Shutdown
MAX4060/MAX4061 DC Bias
3
5
6
8
MAX4061/MAX4062
BIAS
IN+
IN-
AUX_IN
R
BIAS
Output
V
BIAS
x10
x10
The MAX4061 features a low-power, complete shut-
down mode. When SHDN goes low, the supply current
drops to 0.3µA, the output enters a high-impedance
state, and the bias current to the microphone is
switched off. Driving SHDN high enables the amplifier.
SHDN should not be left floating.
The MAX4060 operates from a 4.5V to 5.5V single sup-
ply and the MAX4061/MAX4062 operate from a 2.4V to
5.5V single supply. Bypass the power supply with a
0.1µF capacitor to ground. In systems where analog
and digital grounds are available, the MAX4060/
MAX4061 should be connected to the analog ground.
4.5V TO 5.5V
4
V
CC
GND
7
Applications Information
MAX4060
Power Supplies and Layout
INT/AUX
OUT
1
2
Shutdown Mode
11