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

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

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.

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)

Applications
•Mobile Phones
•PDAs
•Portable electronics devices
•MP3 Players



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Typical Application
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Block Diagram
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Typical Performance
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ParametersValues
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 Yes

Datasheet
TitleSizeDateOther
Language
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) V1492
Kbytes		30-May-06 


Featured Application Notes
TitleSizeDateOther
Language
AN-1452: Application Note 1452 LM4985 Evaluation Board User's Guide1190
Kbytes		26-May-06 


More Application Notes
TitleSizeDateOther
Language
AN-1452: Application Note 1452 LM4985 Evaluation Board User's Guide1190
Kbytes		26-May-06 

Part Number(s)
(NSID)		Top ViewAvailabilityCurrent Reported StockBudgetary PricingStandard Pack Size
LM4985TM/NOPB

RoHS

Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
DIGIKEYWorldwide318
FUTUREWorldwide750
$1.20 each at 1K+ pcsreel
of
250
LM4985TMX/NOPB

RoHS

Full production
Lead Time: 16 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$1.20 each at 1K+ pcsreel
of
3000

Part Number(s)
(NSID)		DescriptionAvailabilityCurrent Reported StockBudgetary PricingStandard Pack Size
LM4985TMEVAL
LM4985 Stereo 135mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output and Digitally Controlled (I2C) Volume ControlFull production


 
DistributorRegionQty
DIGIKEYWorldwide0
NATIONALWorldwide44
$175.00 each1

The LM4985 is a stereo low noise headphone amplifier in a tiny 0.4mm pitch micro SMD package. The LM4985 is designed to meet the demands of mobile phones and other portable communication devices. It is capable of delivering 135 milliwatts of average power to a 16 ohm load with less than 1% distortion (THD+N) from a 5V DC power supply.

The LM4985TMEVAL is an evaluation board designed to ease evaluation and effort during the development of a circuit using the LM4985TM. The evaluation board comes with an I2C card and cable. It is an easy-to-use stand-alone board that requires power and GND, an I2C control signal, aninput signal and anoutput load.

Features:

  • Tiny 12-lead 0.4mm pitch micro SMD
  • Very low iddq (2.3mA cap-coupled, 3mA OCL at 5V)
  • High output power (135mW into 16ohms at 5V)
  • PSRR 77dB at 217Hz
  • THD+N 0.02% cap-coupled at 5V (Pout = 100mA)

Applications:

  • Mobile phones
  • PDAs
  • Portable electronic devices and accessories
  • Toys

Contents:

  • Fully Assembled LM4985TM Evaluation Board
  • I2C interface card and cable
  • Instructions for where to locate and download the datasheet

***Please note: application information can be found in the LM4985 datasheet


Part Number(s)
(NSID)		Top ViewTypePinsMSL RatingPeak ReflowRoHSCAD SymbolsModelsPackage
Marking
Format
LM4985TM/NOPB
MICRO SMD121260RoHSDownloadN/A
XVG
I H2
LM4985TMX/NOPB
MICRO SMD121260RoHSDownloadN/A
XVG
I H2

Reliability Metrics
Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM4985TMCMOS70184060010890004309006723
LM4985TMXCMOS70184060010890004309006723

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.


[Information as of 21-Nov-2009]