Features Fixed Logic Levels Ground referenced outputs High PSRR Available in space-saving micro SMD package Ultra low current shutdown mode Improved pop & click circuitry eliminates noises during turn-on and turn-off transitions No output coupling capacitors, snubber networks, bootstrap capacitors, or gain-setting resistors required Shutdown either channel independently Description The LM4920 is a ground referenced, fixed-gain audio power amplifier capable of delivering 80mW of continuous average power into a 16 single-ended load with less than 1% THD+N from a 3V power supply. The LM4920 features a new circuit technology that utilizes a charge pump to generate a negative reference voltage. This allows the outputs to be biased about ground, thereby eliminating output-coupling capacitors typically used with normal single-ended loads. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4920 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement. The LM4920 features a low-power consumption shutdown mode selectable for either channel separately. This is accomplished by driving either the SD_RC (Shutdown Right Channel) or SD_LC (Shutdown Left Channel) (or both) pins with logic low, depending on which channel is desired shutdown. Additionally, the LM4920 features an internal thermal shutdown protection mechanism. The LM4920 contains advanced pop & click circuitry that eliminates noises which would otherwise occur during turn-on and turn-off transitions. The LM4920 has an internal fixed gain of 1.5V/V. Key Specification Improved PSRR at 217Hz 70dB (typ) Power Output at VDD = 3V, RL = 16, THD <= 1% 80mW (typ) Shutdown Current 0.01µA (typ) Internal Fixed Gain 1.5V/V (typ) Operating Voltage 1.6V to 4.2V Applications Mobile Phones MP3 Players PDAs Portable electronic devices Notebook PCs

Typical Application click for larger image	Connection Diagram click for larger image
Typical Performance click for larger image

Parameters Values Supply Current 7 mA User Supply 3 Volt Power@ 16Ohms, 1% THD 0.08 Watt Power@ 32Ohms, 1% THD 0.065 Watt THD 0.03 % PSRR 70 dB SNR 100 dB Channels 2 Channels Shutdown Type Independent Low Supply Min 1.4 Volt Supply Max 3.6 Volt Output Configuration Differential Temperature Min -40 deg C Temperature Max 85 deg C THD Conditions Po=50mW, f=1kHz, RL=32 Ohms, single channel PSRR Conditions f=217Hz, Vripple=200mVp-p SNR Conditions RL=32, Po=20mW Supply Range +1.4 - +3.6 V

Datasheets

Title		Size	Date	Other Language
	LM4920 Ground-Referenced, Ultra Low Noise, Fixed Gain, 80mW Stereo Headphone Amplifier	1240 Kbytes	18-Oct-06

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM4920TL/NOPB RoHS Status	MICRO SMD	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 0	$0.88 each at 1K+ pcs	reel of 250
LM4920TLX/NOPB RoHS Status	MICRO SMD	Full production Lead Time: 16 weeks	Distributor Region Qty DIGI-KEY Worldwide 0	$0.88 each at 1K+ pcs	reel of 3000

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM4920.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM4920 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM4920TLBD	LM4920TLBD Evaluation Board	Full production	Distributor Region Qty DIGI-KEY Worldwide 0	$150.00 each	1

National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

Lead Free product status is available through the search tool located here

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM4920TL/NOPB	4.601	MICRO SMD	14	1	260	Detail	Download	N/A	XYTT I GH4
LM4920TLX/NOPB	4.601	MICRO SMD	14	1	260	Detail	Download	N/A	XYTT I GH4

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM4920.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM4920 is located at RoHS Status.

CAD Symbols and Models Download LM4920 CAD Symbols

Models N/A