LM4811MM National Semiconductor, LM4811MM Datasheet - Page 11

• Manufacturer Part Number: LM4811MM
• Description: AUDIO POWER AMPLIFIER
• Manufacturer: National Semiconductor
• Type: Dual 150Mw Headphone Amplifierr

Specifications of LM4811MM

• Amplifier Case Style: MSOP
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Supply Voltage Max: 5V
• Leaded Process Compatible: No
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Typical Performance Characteristics
Application Information
DIGITAL VOLUME CONTROL
The LM4811’s gain is controlled by the signals applied to the
CLOCK and UP/DN inputs. An external clock is required to
drive the CLOCK pin. At each rising edge of the clock signal,
the gain will either increase or decrease by a 3dB step
depending on the logic voltage level applied to the UP/DN
pin. A logic high voltage level applied to the UP/DN pin
causes the gain to increase by 3dB at each rising edge of the
clock signal. Conversely, a logic low voltage level applied to
the UP/DN pin causes the gain to decrease 3dB at each
rising edge of the clock signal. For both the CLOCK and
UP/DN inputs, the trigger point is 1.4V minimum for a logic
high level, and 0.4V maximum for a logic low level.
There are 16 discrete gain settings ranging from +12dB
maximum to −33dB minimum. Upon device power on, the
amplifier’s gain is set to a default value of 0dB. However,
when coming out of shutdown mode, the LM4811 will revert
back to its previous gain setting.
Power Supply Rejection Ratio
Frequency Response
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The LM4811’s CLOCK and UP/DN pins should be de-
bounced in order to avoid unwanted state changes during
transitions between V
operation of the digital volume control. A microcontroller or
microprocessor output is recommended to drive the CLOCK
and UP/DN pins.
Power Supply Rejection Ratio
FIGURE 2. Timing Diagram
Supply Current vs
Supply Voltage
IL
and V
IH
. This will ensure correct
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