LM4985_14 Datasheet, PDF (1/33 Pages) Texas Instruments – LAudio Power Amplifier Series Stereo 135mW Low Noise Headphone Amplifier with Selectable Capacitively Coupled

LM4985, LM4985TMEVAL
www.ti.com
SNAS346B – MAY 2006 – REVISED MAY 2006
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) Volume Control
Check for Samples: LM4985, LM4985TMEVAL
FEATURES
1
•23 OCL or Capacitively Coupled Outputs (Patent
Pending)
• I²C Digitally Controlled Volume Control
• Available in Space-Saving 0.4mm Lead-Pitch
DSBGA Package
• Volume Control Range: –76dB to +18dB
• Ultra Low Current Shutdown Mode
• 2.3V - 5.5V Operation
• Ultra Low Noise
APPLICATIONS
• Mobile Phones
• PDAs
• Portable Electronics Devices
• MP3 Players
KEY SPECIFICATIONS (V_DD = 3.6V)
• PSRR: 217Hz and 1kHzs
– Output Capacitor-Less (OCL)
– f_RIPPLE = 217Hz, 77dB (Typ)
– f_RIPPLE = 1kHz, 76dB (Typ)
– Capacitor Coupled (C-CUPL)
– f_RIPPLE = 217Hz, 63dB (Typ)
– f_RIPPLE = 1kHz, 62dB (Typ)
• Output Power Per Channel
(f_IN = 1kHz, THD+N = 1%),
R_L = 16Ω, OCL
– V_DD = 2.5V, 31mW (Typ)
– V_DD = 3.6V, 68mW (Typ)
– V_DD = 5.0V, 135mW (Typ)
• THD+N (f = 1kHz)
– R_LOAD = 16Ω, OCL, P_OUT = 60mW, 0.60
– R_LOAD = 32Ω, OCL, P_OUT = 33mW, 0.031
• Shutdown Current, 0.1µA (Typ)
DESCRIPTION
The LM4985 is a stereo audio power amplifier with
internal digitally controlled volume control. This
amplifier is capable of delivering 68mW_RMS per
channel into a 16Ω load or 38mW_RMS per channel
into a 32Ω 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.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Boomer is a trademark of Texas Instruments.
2
All other trademarks are the property of their respective owners.
3
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006, Texas Instruments Incorporated