80mW, Capless, Stereo Headphone Amplifier with Shutdown
The SGM4914 stereo headphone amplifier is designed for portable equipment where board space is at a premium. The SGM4914 uses capless architecture to produce a ground-referenced output from a single power supply, eliminating the need for large DC-blocking capacitors for output, saving cost, board space, and component height. Additionally, for SGM4914B and SGM4914C, the gain is set internally (-2V/V or -1.5V/V), further reducing component count. For SGM4914A, the gain can be adjusted by external feedback resistors.
The SGM4914 delivers up to 95mW per channel into a 32Ω load and has low 0.01% THD+N. A -90dB power supply rejection ratio (PSRR) at 217Hz allows this device to operate from noisy digital supplies without an additional linear regulator. Comprehensive click-and-pop circuitry suppresses audible clicks and pops on startup and shutdown. Independent left/right, low-power shutdown controls make it possible to optimize power savings in mixed-mode, mono/stereo applications.
The SGM4914 operates from a single 2.7V to 5.5V supply, consumes only 5.6mA supply current, has short-circuit and thermal-overload protections, and is specified over the extended -40℃ to +85℃ temperature range. The SGM4914 is available in a Green TQFN-4×4-20L package.
SGM4914A: External Feedback Gain Network
SGM4914B: Fixed -2V/V Gain
SGM4914C: Fixed -1.5V/V Gain
No Bulky DC-Blocking Capacitors Required
Ground-Referenced Outputs Eliminate DC-Bias Voltage on Headphone Ground Pin
No Degradation of Low-Frequency Response Due to Output Capacitors
95mW into 32Ω Load from 5V Power Supply at THD+N = 0.1% (TYP, per Channel)
Low 0.01% THD+N
High PSRR (-90dB at 217Hz)
Integrated Click-and-Pop Suppression
2.7V to 5.5V Single Supply Operation
Low Quiescent Current (5.6mA at VDD = 5V)
Independent Left/Right, Low-Power Shutdown Controls
Short-Circuit and Thermal-Overload Protections
Undervoltage Lockout Function
-40℃ to +85℃ Operating Temperature Range
Available in a Green TQFN-4×4-20L Package
Notebook PCs
Cellular Phones
PDAs
MP3 Players
Smart Phones
Portable Audio Equipment
