lm4664 National Semiconductor Corporation, lm4664 Datasheet - Page 10

• Manufacturer Part Number: lm4664
• Description: Filterless High Efficiency 1.1w Switching Audio Amplifier
• Manufacturer: National Semiconductor Corporation

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Application Information
the shutdown voltage has crossed the threshold. To mini-
mize the supply current while in the shutdown state, the
Shutdown pin should be driven to GND or left floating. If the
Shutdown pin is not driven to GND, the amount of additional
resistor current due to the internal shutdown resistor can be
found by Equation (1) below.
With only a 0.5V difference, an additional 8.3µA of current
will be drawn while in the shutdown state.
GAIN SELECTION FUNCTION
The LM4664 has fixed selectable gain to minimize external
components, increase flexibility and simplify design. For a
differential gain of 6dB, the Gain Select pin should be per-
(V
SD
- GND) / 60kΩ
(Continued)
(1)
10
manently connected to V
For a differential gain of 12dB, the Gain Select pin should be
permanently connected to GND or driven to a logic low level.
The gain of the LM4664 can be switched while the amplifier
is in PLAY mode driving a load with a signal without damage
to the IC. The voltage on the Gain Select pin should be
switched quickly between GND (logic low) and V
high) to eliminate any possible audible artifacts from appear-
ing at the output. For typical threshold voltages for the Gain
Select function, refer to the Gain Threshold Voltages graph
in the Typical Performance Characteristics section.
DD
or driven to a logic high level.
DD
(logic