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AS1702 - AS1705

8 Detailed Description

The AS1702 - AS1705 are 1.8W high output-current audio amplifiers (configured as BTL amplifiers), and contain inte-

grated low-power shutdown and click- and pop-suppression circuitry. Two inputs (SHDM and SHDN) allow shutdown

mode to be configured as active-high or active-low (see Shutdown Mode on page 11).

Each device has either adjustable or fixed gains (0dB, 3dB, 6dB) (see Ordering Information on page 19).

Bias

The devices operate from a single 2.7 to 5.5V supply and contain an internally generated, common-mode bias voltage

of:

referenced to ground. Bias provides click-and-pop suppression and sets the DC bias level for the audio outputs. Select

the value of the bias bypass capacitor as described in Section BIAS Capacitor on page 15.

Note:

Do not connect external loads to BIAS as this can adversely affect overall device performance.

Shutdown Mode

All devices implement a 100nA, low-power shutdown circuit which reduces quiescent current consumption. As shut-

down mode commences, the bias circuitry is automatically disabled, the device outputs go high impedance, and bias is

driven to GND.

The SHDM input controls the polarity of SHDN:

!

Drive SHDM high for an active-low SHDN input.

!

Drive SHDM low for an active-high SHDN input.

Click-and-Pop Suppression

ing shutdown, the device outputs are driven high impedance to 100k

Ω between both outputs minimizing the energy

present in the audio band, thus preventing clicks and pops.

Table 6. Shutdown Mode Selection Configurations

SHDM

SHDN

Mode

0

0

Shutdown Mode Enabled

0

1

Normal Operation Enabled

1

0

Normal Operation Enabled

1

1

Shutdown Mode Enabled

2

(EQ 1)