LM4985 - LM4985 Stereo 135mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output and Digitally Controlled (I2C) Volume Control

Datasheet Packaging Samples & Pricing Eval. Boards Reliability Design Tools Knowledge Base

Features
•OCL or capacitively coupled outputs (patent pending)
•I2C Digitally Controlled Volume Control
•Available in space-saving 0.4mm lead-pitch micro SMD package
•Volume control range: -76dB to +18dB
•Ultra low current shutdown mode
•2.3V - 5.5V operation
•Ultra low noise

Key Specification

PSRR: 217Hz and 1kHz  
Output Capacitor-less (OCL) 
fRIPPLE = 217Hz77dB (typ)
fRIPPLE = 1kHz76dB (typ)
Capacitor Coupled (C-CUPL) 
fRIPPLE = 217Hz63dB (typ)
fRIPPLE = 1kHz62dB (typ)
Output Power per channel (fIN = 1kHz, THD+N = 1%), RL = 16,OCL 
VDD = 2.5V31mW (typ)
VDD = 3.6V68mW (typ)
VDD = 5.0V135mW (typ)
THD+N (f = 1kHz) 
RLOAD = 16, OCL, POUT = 60mW0.60
RLOAD = 32, OCL, POUT = 33mW0.031
Shutdown Current0.1µA (typ)

General Description

The LM4985 is a stereo audio power amplifier with internal digitally controlled volume control. More...


Applications

•Mobile Phones
•PDAs
•Portable electronics devices
•MP3 Players
  Typical Application
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Parametric Table     expand
Parametric Table    collapse
Power@ 8Ohms, 1% THD Undefined Watt
Power@ 16Ohms, 1% THD 0.135 Watt
Power@ 32Ohms, 1% THD 0.08 Watt
Power@ 8Ohms, 10% THD Undefined Watt
THD 0.08 %
PSRR 77 dB
Channels 2 Channels
THD Conditions Pout = 100mW, f = 1kHz, Rload = 16ohms
PSRR Conditions OCL mode, f = 217Hz, Rload = 16ohms
Power@ 8Ohms, 1% THD Undefined Watt
Power@ 16Ohms, 1% THD 0.135 Watt
Power@ 32Ohms, 1% THD 0.08 Watt
Power@ 8Ohms, 10% THD Undefined Watt
THD 0.08 %
PSRR 77 dB
Channels 2 Channels
THD Conditions Pout = 100mW, f = 1kHz, Rload = 16ohms
PSRR Conditions OCL mode, f = 217Hz, Rload = 16ohms
User Supply 5 Volt
Shutdown Type I2C
Supply Range +2.2 - +5.5 V
Volume Control 32 step I2C
Exposed DAP No
Capless Headphone Yes
Temperature Min -40 deg C
Temperature Max 85 deg C
Automotive Selection Guide Yes
View Using Catalog


Typical Performance

click for larger image


  Additional Resources
Design Tools (see below)


Block Diagram

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Datasheet
RoHS Compliance Information Size in KbytesDate Click link below to Download
LM4985 Boomer ® Audio Power Amplifier Series Stereo 135mW Low Noise Headphone Amplifier with Selectable Capacitively Coupled or Output Capacitor-less (OCL) Output and Digitally Controlled (I2C) V 1492 Kbytes 30-May-06 Download

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Package Availability, Models, Samples & Pricing
Part NumberPackageFactory Lead TimeModelsSamples &
Electronic
Orders		Budgetary PricingStd
Pack
Size		Package
Marking
Format
TypePinsSpec.MSL
Rating		Peak
Reflow		RoHS
Report		CAD
Symbols		WeeksQtyQty$US each
LM4985TMEVALLM4985 Stereo 135mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output and Digitally Controlled (I2C) Volume ControlFull productionN/A
 
Buy Now 		1+$175.001-
N/AN/A
LM4985TMMICRO SMD12NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$1.20reel
of
250		XVG
I H2
6 weeksN/A
LM4985TMXMICRO SMD12NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$1.20reel
of
3000		XVG
I H2
16 weeksN/A

General Description

The LM4985 is a stereo audio power amplifier with internal digitally controlled volume control. This amplifier is capable of delivering 68mWRMS per channel into a 16 load or 38mWRMS per channel into a 32 load at 1% THD when powered by a 3.6V power supply and operating in the OCL mode.

Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. To that end, the LM4985 features two functions that optimize system cost and minimize PCB area: an integrated, digitally controlled (I2C bus) volume control and an operational mode that eliminates output signal coupling capacitors (OCL mode). Since the LM4985 does not require bootstrap capacitors, snubber networks, or output coupling capacitors, it is optimally suited for low-power, battery powered portable systems. For added design flexibility, the LM4985 can also be configured for single-ended capacitively coupled outputs.

The LM4985 features a current shutdown mode for micropower dissipation and thermal shutdown protection.

Reliability Metrics

Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM4985TMCMOS7016561009540004270700104
LM4985TMXCMOS7016561009540004270700104

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.


Design Tools

TitleSize in Kbytes Date Click link below to Download    
Audio Amplifier Digital Control Interface Evaluation Board Software 16 Kbytes 27-Mar-2008 View    

If you have trouble printing or viewing PDF file(s), see Printing Problems.

Application Notes

TitleSize in Kbytes Date Click link below to Download
AN-1452: Application Note 1452 LM4985 Evaluation Board User's Guide 1190 Kbytes 26-May-06 Download

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[Information as of 5-Jul-2009]