LM4831VF National Semiconductor, LM4831VF Datasheet - Page 5

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LM4831VF

Manufacturer Part Number
LM4831VF
Description
IC AMP AUDIO PWR 1.5W AB 44LQFP
Manufacturer
National Semiconductor
Series
Boomer®r
Type
Class ABr
Datasheet

Specifications of LM4831VF

Output Type
2-Channel (Stereo)
Max Output Power X Channels @ Load
1.5W x 2 @ 4 Ohm
Voltage - Supply
2.7 V ~ 5.5 V
Features
Depop, Input Multiplexer, Microphone, Shutdown
Mounting Type
Surface Mount
Package / Case
44-LQFP
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
*LM4831VF

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Pin Descriptions
VDDA
VDDD
GNDA,
GNDD,
GNDM
This is the analog power supply pin
which powers all internal circuitry, with
the exceptions of the output amplifiers
and the digital logic in the Beep and
Switching circuit sections. This pin
should be connected to the same
supply voltage as the two VDDD pins
(typically 5V), but have a separate
ground return path to the supply
ground to minimize interaction with the
high current amplifier returns and
digital switching noise. In addition, this
pin should be bypassed with a 0.01
µF–0.1 µF capacitor.
These pins are the “digital” and high
current power supply pins which
power the stereo bridged output
amplifier and the digital logic in the
Beep and Switching circuit sections.
These pins should be connected to
the same supply voltage as the VDDA
pin (typically 5V), but have a separate
return path to the supply to avoid
interferring with low level signals. In
addition, this pin should be bypassed
with a 0.01 µF–0.1 µF capacitor. At
the power supply connection, a bulk
storage capacitor of at least 10 µF will
reduce the instantaneous current
demanded from the power supply.
These are the power supply ground
pins. GNDA is the ground pin for the
low current analog circuitry. The two
GNDD pins are for the digital logic
and bridged output amplifiers. GNDM
is the ground for the microphone
amplifier. Make sure that the high
current GNDD paths are not returned
through the low current GNDM or
GNDA paths. These four ground pins
should be star-grounded at a stable,
low-impedance, noise-free system
ground.
5
BYPASS
HP-IN
DS-IN
This voltage at this pin is nominally
1/2 VDDD and is created by an
internal 50 k
node should be bypassed with a
capacitor value from 0.1 µF-1.0 µF.
Increasing the capacitor value will
increase the ramp time of the
amplifiers, thereby improving turn-on
pop performance. 0.1µF is typical for
the bypass capacitor. In addition, a 1
M
positive supply is shown in Figure 3 .
This resistor guarantees that the
LM4831 will turn-on if the device is
powered up with both the PWRDWN
and DS-IN pins high. If the the
LM4831 will never enter that state,
then the 1M
removed.
This pin places the output power
amplifier in “headphone” mode. If
HP-IN is low, the amplifier is in
bridged mode and the 2:1 mux passes
the input on the EQ_IN pin. If HP-IN is
high, the amplifier is in single-ended
mode and the 2:1 mux passes the
output of the mixing stage.
Single-ended mode places the
non-inverting amplifier in the output
amplifiers into a high impedance state.
HP-IN also has priority over the DS-IN
pin, so if HP-IN and DS-IN are both
high, the device is in single-ended
mode and the stereo line out amplifier
is in a high-impedance state.
This pin is used to put the LM4831
into “docking-station” mode and
control the line out drivers and the
state of the internal 2:1 analog
multiplexer. If DS-IN is high, the
stereo line out amplifier is on and the
stereo bridged amplifier is in a high
impedance state. Asserting the DS-IN
pin also changes the 2:1 analog
multiplexer output from the stereo
signal on the L_EQIN and R_EQIN
pins to the internal path from the
stereo input mixer.
resistor from the bypass pin to the
resistor can be
resistor divider. This
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