LM4874 Datasheet, PDF (1/21 Pages) National Semiconductor (TI) – 2.1W Differential Input, BTL Output Stereo Audio Amplifier with Selectable Gain and Shutdown

August 2002
LM4874
2.1W Differential Input, BTL Output Stereo Audio
Amplifier with Selectable Gain and Shutdown
General Description
The LM4874 features differential stereo inputs, BTL (bridge-
tied load) outputs, and four externally selectable fixed gains.
Operating on a single 5V supply, the LM4874 delivers 1.2W,
1.9W, or 2.1W (typ) of output power to an 8Ω, 4Ω, or 3Ω BTL
load (Note 1), respectively, with less than 1% THD+N. The
LM4874’s gain is selected using two digital inputs. The nomi-
nal gain values are 6dB, 10dB, 15.6dB, and 21.6dB.
The LM4874 is designed for notebook and other handheld
portable applications. It delivers high quality output power
from a surface-mount package and requires few external
components.
Other features include an active-low micropower shutdown
mode input and thermal shutdown protection.
Key Specifications
j BTL output power
R_L = 8Ω, V_DD = 5.0V, and THD+N = 1%
j Micropower shutdown current
j PSRR (@ 1kHz, V_DD = 5V, (Fig.1))
1.2W (typ)
0.1µA (typ)
62dB (typ)
Features
n Fully differential input and output
n Internal gain set: 6dB, 10dB, 15.6dB, and 21.6dB
n Improved ’click and pop’ suppression
n Thermal shutdown protection circuit
n Ultra low current micropower shutdown mode
n 3.0V to 5.5V operation
n Available in space-saving exposed-DAP TSSOP
package
j BTL output power
R_L = 3Ω, V_DD = 5.0V, and THD+N = 1%
j BTL output power
R_L = 4Ω, V_DD = 5.0V, and THD+N = 1%
2.1W (typ)
1.9W (typ)
Applications
n Notebook computers
n PDAs
n Portable electronic devices
Connection Diagram
Top View
20046902
Order Number LM4874MH
See NS Package Number MXA20A for Exposed-DAP TSSOP
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© 2002 National Semiconductor Corporation DS200469
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