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National Semiconductor
National Semiconductor

LM4862M Datasheet

675 mW Audio Power Amplifier with Shutdown Mode


LM4862M Datasheet Preview


May 1997
LM4862
675 mW Audio Power Amplifier with Shutdown Mode
General Description
The LM4862 is a bridge-connected audio power amplifier ca-
pable of delivering typically 675 mW of continuous average
power to an 8load with 1% (THD) from a 5V power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4862 does not require
output coupling capacitors, bootstrap capacitors, or snubber
networks, it is optimally suited for low-power portable sys-
tems.
The LM4862 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism.
The unity-gain stable LM4862 can be configured by external
gain-setting resistors.
Key Specifications
n THD at 500 mW continuous average
output power at 1 kHz into 8
n Output power at 10% THD+N at
1 kHz into 8
n Shutdown Current
1% (max)
825 mW (typ)
0.7 µA (typ)
Features
n No output coupling capacitors, bootstrap capacitors or
snubber circuits are necessary
n Small Outline or DIP packaging
n Unity-gain stable
n External gain configuration capability
n Pin compatible with LM4861
Applications
n Portable Computers
n Cellular Phones
n Toys and Games
Typical Application
Connection Diagram
Small Outline and DIP Package
DS012342-2
Top View
Order Number LM4862M, LM4862N
See NS Package Number M08A or N08E
*Refer to the Application Information section for information
concerning proper selection of the input coupling capacitor.
FIGURE 1. Typical Audio Amplifier Application Circuit
DS012342-1
Boomer® is a registered trademark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation DS012342
www.national.com
Page 1

Absolute Maximum Ratings (Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
Storage Temperature
Input Voltage
Power Dissipation (Note 3)
ESD Susceptibility (Note 4)
ESD Susceptibility (Note 5)
Junction Temperature
Soldering Information
Small Outline Package
Vapor Phase (60 sec.)
6.0V
−65˚C to +150˚C
−0.3V to VDD + 0.3V
Internally limited
3500V
250V
150˚C
215˚C
Infrared (15 sec.)
220˚C
See AN-450 “Surface Mounting and their Effects on
Product Reliability” for other methods of soldering surface
mount devices.
Thermal Resistance
θJC (typ) — M08A
θJA (typ) — M08A
θJC (typ) — N08E
θJA (typ) — N08E
35˚C/W
170˚C/W
37˚C/W
107˚C/W
Operating Ratings
Temperature Range
TMIN TA TMAX
Supply Voltage
−40˚C TA 85˚C
2.7V VDD 5.5V
Electrical Characteristics(Note 1) (Note 2)
The following specifications apply for VDD = 5V unless otherwise specified. Limits apply for TA = 25˚C.
Symbol
Parameter
Conditions
LM4862
Typical Limit
Units
(Limits)
(Note 6) (Note 7)
VDD Supply Voltage
2.7 V (min)
5.5 V (max)
IDD
ISD
VOS
PO
THD + N
PSRR
Quiescent Power Supply Current
Shutdown Current
Output Offset Voltage
Output Power
Total Harmonic Distortion +
Noise
Power Supply Rejection Ratio
VIN = 0V, IO = 0A (Note 8)
VPIN1 = VDD
VIN = 0V
THD = 1% (max); f = 1 kHz; RL = 8
THD + N = 10%; f = 1 kHz; RL = 8
PO = 500 mWrms; RL = 8
AVD = 2; 20 Hz f 20 kHz
VDD = 4.9V to 5.1V
3.6 6.0 mA (max)
0.7 5 µA (max)
5 50 mV (max)
675 500 mW (min)
825 mW
0.55 %
50 dB
Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is func-
tional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guar-
antee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is
given, however, the typical value is a good indication of device performance.
Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature TA. The maximum
allowable power dissipation is PDMAX = (TMAX − TA)/θJA. For the LM4862, TJMAX = 150˚C. The typical junction-to-ambient thermal resistance, when board mounted,
is 170˚C/W for package number M08A and is 107˚C/W for package number N08E.
Note 4: Human body model, 100 pF discharged through a 1.5 kresistor.
Note 5: Machine Model, 200 pF–240 pF discharged through all pins.
Note 6: Typicals are measured at 25˚C and represent the parametric norm.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier.
www.national.com
2
Page 2

Automatic Switching Circuit
FIGURE 2. Automatic Switching Circuit
External Components Description (Figure 1)
DS012342-21
Components
1. Ri
2. Ci
3. RF
4. CS
5. CB
Functional Description
Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also forms a
high pass filter with Ci at fc = 1/(2πRiCI).
Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a
highpass filter with Ri at fc = 1/(2πRiCi). Refer to the section, Proper Selection of External Components,
for an explanation of how to determine the value of Ci.
Feedback resistance which sets the closed-loop gain in conjunction with Ri.
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
section for proper placement and selection of the supply bypass capacitor.
Bypass pin capacitor which provides half-supply filtering. Refer to the Proper Selection of External
Components section for proper placement and selection of the half-supply bypass capacitor.
3 www.national.com
Page 3

Typical Performance Characteristics
THD+N vs Frequency
THD+N vs Frequency
THD+N vs Frequency
DS012342-3
THD+N vs Output Power
DS012342-4
THD+N vs Output Power
DS012342-5
THD+N vs Output Power
Output Power vs
Supply Voltage
DS012342-6
Output Power vs
Supply Voltage
DS012342-7
Output Power vs
Supply Voltage
DS012342-8
DS012342-9
DS012342-10
DS012342-11
www.national.com
4
Page 4
Part Number LM4862M
Manufactur National Semiconductor
Description 675 mW Audio Power Amplifier with Shutdown Mode
Total Page 10 Pages
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LM4862M datasheet
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