MAX4060EUA Просмотр технического описания (PDF) - Maxim Integrated

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MAX4060EUA

Differential Microphone Preamplifiers with Internal Bias and Complete Shutdown

Maxim Integrated 

Differential Microphone Preamplifiers with

Internal Bias and Complete Shutdown

100kΩ

2.4V TO 5.5V

RBIAS

4 BIAS

CBIAS

5

VCC

VBIAS

MAX4062

9 AUX_IN x10

INT/AUX 2

6 IN+

OUT 3

7 IN-

Figure 1. MAX4062 with Auxiliary Input Configuration

G1 10

G2 1

GND

8

ential inputs and to set the lower 3dB point (fCUT) of the

amplifier by sizing the output capacitor appropriately.

The input impedance matching on the differential input

is typically 1%, allowing input capacitor matching to be

effective at improving low-frequency PSRR.

Common-Mode Rejection Ratio

The common-mode rejection ratio (CMRR) refers to the

amount of rejection that the amplifier is capable of pro-

viding to any signal applied equally to the IN+ and IN-

inputs. In the case of amplifying low-level microphone

signals in noisy digital environments, it is a key figure of

merit. In audio circuits, this is generally measured for

VIN as an AC signal:

CMRR(dB) = ADM / ACM

where ADM is the differential gain, ACM is the common-

mode gain.

Input voltages are sufficiently small such that the output

is not clipped in either differential or common-mode

application. The topology used in the MAX4061/

MAX4062 means that the CMRR actually improves at

higher differential gains—another advantage of using

differential sensing.

Auxiliary Input

The auxiliary input is a single-ended input intended to

be used with a jack-socket-type microphone input

(Figure 1). Internal DC-bias components (as on the

main inputs) allow the input signal to be AC-coupled.

Mechanically switched jack sockets can be used in

conjunction with the INT/AUX select pin, allowing the

auxiliary microphone input to be automatically selected

when a jack socket is inserted.

Microphone Bias Voltage

MAX4060

The MAX4060 has a microphone bias voltage designed

to comply with the Microsoft/Intel PC99/2001 audio

standard. It features source impedance of greater than

2kΩ, and delivers more than 2V of bias when loaded

with a current of 800µA. This limits operation of this part

to supplies between 4.5V to 5.5V (see Figure 2).

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