LM4991MA National Semiconductor, LM4991MA Datasheet - Page 10
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LM4991MA
Manufacturer Part Number
LM4991MA
Description
Manufacturer
National Semiconductor
Datasheet
1.LM4991MA.pdf
(15 pages)
Specifications of LM4991MA
Operational Class
Class-AB
Audio Amplifier Output Configuration
1-Channel Mono
Output Power (typ)
1.5x1@8OhmW
Audio Amplifier Function
Speaker
Total Harmonic Distortion
0.2@8Ohm@0.5W%
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
64dB
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
8
Package Type
SOIC N
Lead Free Status / Rohs Status
Not Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM4991MA
Manufacturer:
NS/国半
Quantity:
20 000
Company:
Part Number:
LM4991MAX
Manufacturer:
MAXIM
Quantity:
6 870
Part Number:
LM4991MAX
Manufacturer:
NS/国半
Quantity:
20 000
Company:
Part Number:
LM4991MAX/NOPB
Manufacturer:
NS/TI
Quantity:
100
www.national.com
Typical Performance Characteristics
Application Information
EXPOSED-DAP PACKAGE PCB MOUNTING
CONSIDERATION
The LM4991’s exposed-DAP (die attach paddle) package
(LD) provides a low thermal resistance between the die and
the PCB to which the part is mounted and soldered. This
allows rapid heat transfer from the die to the surrounding
PCB copper traces, ground plane, and surrounding air. The
result is a low voltage audio power amplifier that produces
2W at ≤ 1% THD with a 4Ω load. This high power is achieved
through careful consideration of necessary thermal design.
Failing to optimize thermal design may compromise the
LM4991’s high power performance and activate unwanted,
though necessary, thermal shutdown protection.
The LD package must have its DAP soldered to a copper
pad on the PCB. The DAP’s PCB copper pad is connected to
a large plane of continuous unbroken copper. This plane
forms a thermal mass, heat sink, and radiation area. Place
the heat sink area on either outside plane in the case of a
Supply Voltage, R
Frequency Response vs
Input Capacitor Size
Output Power vs
L
= 16Ω
20074069
20074071
10
(Continued)
two-sided PCB, or on an inner layer of a board with more
than two layers. Connect the DAP copper pad to the inner
layer or backside copper heat sink area with 4(2x2) vias. The
via diameter should be 0.012in-0.013in with a 1.27mm pitch.
Ensure efficient thermal conductivity by plating through the
vias.
Best thermal performance is achieved with the largest prac-
tical heat sink area. If the heatsink and amplifier share the
same PCB layer, a nominal 2.5in
operation with a 4Ω load. Heatsink areas not placed on the
same PCB layer as the LM4991 should be 5in
same supply voltage and load resistance. The last two area
recommendations apply for 25˚C ambient temperature. In-
crease the area to compensate for ambient temperatures
above 25˚C. The LM4991’s power de-rating curve in the
Typical Performance Characteristics shows the maximum
power dissipation versus temperature. An example PCB lay-
out for the LD package is shown in the Demonstration
Board Layout section. Further detailed and specific infor-
mation concerning PCB layout, fabrication, and mounting an
Supply Voltage, R
Output Power vs
2
L
area is necessary for 5V
= 32Ω
2
20074070
(min) for the