LM4891 NSC [National Semiconductor], LM4891 Datasheet

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LM4891

Manufacturer Part Number
LM4891
Description
1 Watt Audio Power Amplifier
Manufacturer
NSC [National Semiconductor]
Datasheet

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© 2002 National Semiconductor Corporation
LM4891
1 Watt Audio Power Amplifier
General Description
The LM4891 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other por-
table communication device applications. It is capable of
delivering 1 watt of continuous average power to an 8Ω BTL
load with less than 1% distortion (THD+N) 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. The LM4891 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other low voltage appli-
cations where minimal power consumption is a primary re-
quirement.
The LM4891 features a low-power consumption shutdown
mode, which is achieved by driving the shutdown pin with
logic high. Additionally, the LM4891 features an internal ther-
mal shutdown protection mechanism.
The LM4891 contains advanced pop & click circuitry which
eliminates noises which would otherwise occur during
turn-on and turn-off transitions.
The LM4891 is unity-gain stable and can be configured by
external gain-setting resistors.
Typical Application
Boomer
®
is a registered trademark of National Semiconductor Corporation.
FIGURE 1. Typical Audio Amplifier Application Circuit
DS200074
DC
Key Specifications
Features
n Available in space-saving packages: micro SMD, MSOP,
n Ultra low current shutdown mode
n BTL output can drive capacitive loads
n Improved pop & click circuitry eliminates noises during
n 2.2 to 5.5V operation
n No output coupling capacitors, snubber networks or
n Thermal shutdown protection
n Unity-gain stable
n External gain configuration capability
Applications
n Mobile Phones
n PDAs
n Portable electronic devices
j
j
j
j
SOIC, and LLP
turn-on and turn-off transitions
bootstrap capacitors required
PSRR at 217Hz, V
Power Output at 5.0V & 1% THD
Power Output at 3.3V & 1% THD
Shutdown Current
DD
20007401
= 5V, 8Ω Load
October 2002
400mW (typ)
www.national.com
0.1µA (typ)
62dB (typ)
1.0W (typ)

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LM4891 Summary of contents

Page 1

... The LM4891 contains advanced pop & click circuitry which eliminates noises which would otherwise occur during turn-on and turn-off transitions. The LM4891 is unity-gain stable and can be configured by external gain-setting resistors. Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit Boomer ® ...

Page 2

... Connection Diagrams 8 Bump micro SMD Top View Order Number LM4891IBP, LM4891IBPX See NS Package Number BPA08DDB 8 Bump micro SMD Marking Top View X - Date Code T - Die Traceability G - Boomer Family G - LM4891IBP Mini Small Outline (MSOP) Package Top View Order Number LM4891MM See NS Package Number MUA08A ...

Page 3

... A LM4891 Typical Limit (Note 6) (Note 7) 3.5 mA (max) 0.1 µA (max) 0.4 0 217Hz 1kHz) LM4891 Typical Limit (Note 6) (Note 7) 2.6 mA (max) 0.1 µA (max) www.national.com 56˚C/W 190˚C/W 220˚C/W ≤ 85˚C A ≤ 5.5V DD Units (Limits 25˚C. ...

Page 4

... V = 200mV sine p-p ripple –T )/θ or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4891, see power derating A JA exceeds 6V (to a max then most of the excess current will flow through the ESD protection circuits the device occurs at an output power level significantly below full output power. P ...

Page 5

Typical Performance Characteristics THD+N vs Frequency 5V, 8Ω and PWR = 250mW DD L THD+N vs Frequency 2.6V, 8Ω and PWR = 100mW DD L THD+N vs Power Out @ ...

Page 6

Typical Performance Characteristics THD+N vs Power Out @ V = 2.6V, 8Ω Power Supply Rejection Ratio (PSRR) Input terminated with 10Ω R Power Supply Rejection Ratio (PSRR) Input terminated with 10Ω R www.national.com (Continued) , 1kHz L 20007443 ...

Page 7

Typical Performance Characteristics Power Dissipation vs Output Power V = 3.3V DD Output Power vs Load Resistance Supply Current vs Shutdown Voltage (Continued 20007449 20007451 Clipping (Dropout) Voltage vs 20007474 7 Power Dissipation vs Output Power = ...

Page 8

Typical Performance Characteristics Open Loop Frequency Response Load DD Power Derating Curves (P = 670mW) DMAX Power Derating - 10 Pin LD Pkg P = 670mW, 5V, 8Ω DMAX www.national.com (Continued) Open Loop Frequency Response 20007475 ...

Page 9

... By adding additional copper foil, the thermal resistance of the application can be reduced from a free air value of 150˚C/W, resulting in higher P can be added to any of the leads connected to the LM4891 especially effective when connected to V the output pins. Refer to the application information on the LM4891 reference design board for an example of good heat sinking ...

Page 10

... Supply Voltage curve in the Typical Performance Characteristics section standard voltage, in most applications, chosen for the supply rail. Extra supply voltage creates headroom that al- lows the LM4891 to reproduce peaks in excess of 1W with- , forms a out producing audible distortion. At this time, the designer i ...

Page 11

... This feedback capacitor creates a low pass filter that elimi- With and f (Continued) VD 300 kHz which is much smaller than the LM4891 GBWP of in con- 2.5 MHz. This figure displays that if a designer has a need to i design an amplifier with a higher differential gain, the LM4891 can still be used without running into bandwidth limitations ...

Page 12

... Application Information FIGURE 3. Differential Amplifier Configuration for LM4891 FIGURE 4. Reference Design Board and Layout - micro SMD www.national.com (Continued) 12 20007429 20007425 ...

Page 13

... Application Information LM4891 micro SMD BOARD ARTWORK Silk Screen Bottom Layer Inner Layer V DD (Continued) 20007457 20007459 20007461 13 Top Layer 20007458 Inner Layer Ground 20007460 www.national.com ...

Page 14

Application Information FIGURE 5. Reference Design Board and PCB Layout Guidelines - MSOP & SO Boards www.national.com (Continued) 14 20007468 ...

Page 15

... Application Information LM4891 SO DEMO BOARD ARTWORK Silk Screen Top Layer Bottom Layer LM4891 MSOP DEMO BOARD ARTWORK (Continued) 20007462 20007463 20007464 15 Silk Screen 20007465 Top Layer 20007466 Bottom Layer 20007467 www.national.com ...

Page 16

... Application Information Item Part Number 1 551011208-001 LM4891 Mono Reference Design Board 10 482911183-001 LM4891 Audio AMP 20 151911207-001 Tant Cap 1uF 16V 10 21 151911207-002 Cer Cap 0.39uF 50V Z5U 20% 1210 25 152911207-001 Tant Cap 1uF 16V 10 30 472911207-001 Res 20K Ohm 1/10W 5 35 210007039-002 Jumper Header Vertical Mount 2X1 0.100 2 ...

Page 17

... Recommend non-solder mask defined landing pad. 4. Pin 1 is established by lower left corner with respect to text orientation pins are numbered counterclockwise. 5. Reference JEDEC registration MO-211, variation BC 1.361 8-Bump micro SMD Order Number LM4891IBP, LM4891IBPX NS Package Number BPA08DDB ± ± 0. 1.361 0. 0.850 17 ± ...

Page 18

... Physical Dimensions www.national.com inches (millimeters) unless otherwise noted (Continued) MSOP Order Number LM4891MM NS Package Number MUA08A 18 ...

Page 19

... Physical Dimensions inches (millimeters) unless otherwise noted (Continued) SO Order Number LM4891M NS Package Number M08A 19 www.national.com ...

Page 20

... National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. inches (millimeters) unless otherwise noted (Continued) LLP Order Number LM4891LD NS Package Number LDA10B 2. A critical component is any component of a life ...

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