Low power headphone amp

Overview | Key Feature 1 | Key Feature 2 | Key Feature 3 | Lineup

Simple operation from a single battery

Overview

Compact portable equipment put to continuous use, such as IC recorders, electronic dictionaries, and portable audio players, require longer operating times from a single battery.
To meet this need ROHM offers the BU7150NUV headphone amp capable of operation from only 0.93V.

Key Features
  • Wide operating power supply voltage range
    (0.93V to 3.5V, Ta=0ºC to 85ºC)
    (1.03V to 3.5V, Ta=-40ºC to 85ºC)
  • Selectable modes: BTL for monaural speakers,
    single-end stereo headphone
  • Unity gain results in stable operation
  • Clicking/popping noise reduction circuit built in
  • Shutdown mode (low power consumption mode)
  • Built-in mute function (high-speed turn ON upon mute release)
  • Integrated thermal shutdown circuit
  • Power ON reset circuit not affected by the supply voltage startup slew rate
  • Compact package

Key Feature 1: Wide operating voltage range (0.93V to 3.5V)
enables operation from one or two batteries

The wide operating voltage range supports operation from one or two batteries. In addition, BTL connection allows the BU7150NUV to be used as a high-output monaural speaker amp. Additional features include an automatic startup sequence control circuit, power ON reset function, and clicking/popping noise reduction circuit for high-performance operation.

Maximum Output Power vs. Supply Voltage
Stereo Headphone Amp Circuit Example

Key Feature 2: Low voltage, low current (1mA) operation results in longer battery life

The BU7150NUV features low 1mA current consumption and a wide voltage range (0.93V to 3.5V). When operating from a single battery, conventional headphone amps require a step-up circuit, which increases power consumption as well as loss (through step-up operation). In contrast, the BU7150NUV eliminates the need for a step-up circuit, reducing power consumption for longer battery life.

Power Consumption Comparison (Single-Cell Battery Drive)
  Conventional Class AB Amp  BU7150NUV
 Supply Voltage (typ) 3V 1.5V
 No-Signal Current 5.0mA 1.0mA
 Power Consumption 15.0mW 1.5mW
 DC/DC Efficiency 90% -
 Total Power Consumption 16.7mW 1.5mW

Key Feature 3: Built-in startup sequence circuit reduces load and controls clicking noise

A startup sequence circuit is built in to ensure high fidelity audio output during ON/OFF operation. Clicking/popping noise reduction is automatically performed, elminating the need for microcontroller control. In addition, the power ON reset function is not dependent on the supply voltage startup slew rate, simplifying use considerably.

Built-in startup sequence eliminates microcontroller load and eliminates popping nose

Lineup

Part No. Power
Supply
Voltage
(V)
No-Signal
Circuit
Current
(mA)
Max.
Output
Power
(mW)
Harmonic
distortion
(%)
Output
noise
voltage
(Vrms)
Package
RL=8BTL RL=16SE RL=8BTL RL=16SE
BU7150NUV 0.93
to
3.5
1.0 85 (VDD
=1.5V)
14 (VDD
=1.5V)
0.2
(25mW)
0.1
(5mW)
10 VSON010V3030
3mm × 3mm
H=1.0mmMax.

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