LM4894MMX/NOPB National Semiconductor, LM4894MMX/NOPB Datasheet - Page 11

• Manufacturer Part Number: LM4894MMX/NOPB
• Description: IC AMP AUDIO PWR 1W SMD
• Manufacturer: National Semiconductor
• Series: Boomer®r

Specifications of LM4894MMX/NOPB

• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 1W x 1 @ 8 Ohm
• Voltage - Supply: 2.2 V ~ 5.5 V
• Features: Depop, Differential Inputs, Shutdown, Thermal Protection
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
• Operational Class: Class-AB
• Audio Amplifier Output Configuration: 1-Channel Mono
• Output Power (typ): 1x1@8OhmW
• Audio Amplifier Function: Speaker
• Total Harmonic Distortion: 0.1@8Ohm@400mW%
• Single Supply Voltage (typ): 3/5V
• Dual Supply Voltage (typ): Not RequiredV
• Power Supply Requirement: Single
• Rail/rail I/o Type: No
• Power Supply Rejection Ratio: 87dB
• Single Supply Voltage (min): 2.2V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 10
• Package Type: MSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Typical Performance Characteristics
Non-LD Specific Characteristics
Application Information
DIFFERENTIAL AMPLIFIER EXPLANATION
The LM4894 is a fully differential audio amplifier that fea-
tures differential input and output stages. Internally this is
accomplished by two circuits: a differential amplifier and a
common mode feedback amplifier that adjusts the output
voltages so that the average value remains V
setting the differential gain, the amplifier can be considered
to have "halves". Each half uses an input and feedback
resistor (R
(see Figure 1). With R
at -R
It is extremely important to match the input resistors to each
other, as well as the feedback resistors to each other for best
F
/R
i
for each half. This results in a differential gain of
i1
and R
DC Common-Mode Voltage
Common-Mode Voltage
F1
) to set its respective closed-loop gain
i1
A
= R
VD
PSRR vs
THD vs
i2
= -R
and R
F
/R
i
F1
= R
F2
, the gain is set
DD
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amplifier performance. See the Proper Selection of Exter-
nal Components section for more information. A differential
amplifier works in a manner where the difference between
the two input signals is amplified. In most applications, this
would require input signals that are 180˚ out of phase with
each other. The LM4894 can be used, however, as a single
ended input amplifier while still retaining its fully differential
benefits. In fact, completely unrelated signals may be placed
on the input pins. The LM4894 simply amplifies the differ-
ence between them. Figures 2 and 3 show single-ended
applications of the LM4894 that still take advantage of the
differential nature of the amplifier and the benefits to PSRR,
common-mode noise reduction, and "click and pop" reduc-
tion.
All of these applications, either single-ended or fully differ-
ential, provide what is known as a "bridged mode" output
(bridge-tied-load, BTL). This results in output signals at V
and V
o2
that are 180˚ out of phase with respect to each
DC Common-Mode Voltage
Common-Mode Voltage
PSRR vs
THD vs
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