Low Voltage Headphone Amplifier


ROHM has recently announced the development of the BU7150NUV, a low power consumption headphone amplifier that supports low voltage operation from 0.93V, making it compatible with single-cell battery applications such as IC recorders and noise canceling headphones.

The continuing evolution of low-voltage technology has engendered a variety of portable devices that operate on a single dry cell (1.5V). However, most headphone amplifiers still require a minimum operating voltage above 1.5V, necessitating a step-up DC/DC converter. But this method results in conversion loss, typically around 10%.

Although there are headphone amplifiers that operate at voltages around 0.9V, when used in sets that operate from dry cell batteries the power supply startup time increases due to the increase in output resistance based on battery discharge, making it difficult to use in products with limited power supply voltage startup times.

The BU7150NUV alleviates these problems by ensuring stable operation from 0.93V, eliminating the need for a boost converter circuit in single-cell applications. In addition, an internal power ON reset function frees the IC from the effects of the power supply voltage startup time. Other features include: ① Compatibility with both stereo headphone and monaural speaker amplifiers, ② Highly realistic sound reproduction due to excellent crosstalk properties (85dB), ③ An integrated automatic ON/OFF sequence circuit that reduces microcontroller load, and ④ A built-in click and pop noise reduction circuit. A wide operating voltage range is also offered (3.5V max.), making it ideal for dual-battery sets such as electronic dictionaries and electronic toys (no major modifications required).

Pricing : 400yen/unit (For Sample Shipments)
Availability : Now (OEM quantities)

Key Features

  • Wide operating power supply range 0.93V–3.5V (from 0ºC to 85ºC), 1.03V–3.5V (from −40ºC to 85ºC)
  • Built-in power ON reset circuit eliminates restrictions based on the power supply voltage through rate
  • Integrated automatic sequencing corresponding to shutdown mode and mute mode
  • Variable startup completion time (via external components)
  • Selectable BTL mode for monaural speakers and single-end stereo headphone mode
  • Built-in click and pop noise reduction circuit
  • Equipped with a thermal shutdown protection circuit
  • Compact package (VSON010V3030: 3.0mm × 3.0mm h = 1.0mm)

Operating Voltage Comparison

Operating Voltage Comparison

Application Example

Application Example

Absolute Maximum Ratings

Parameter Symbol Rating Units
Power Supply Voltage VDD 4.5 V
Input Voltage VIN VSS-0.3 to VDD+0.3 V
Input Current IIN -10 to 10 mA
Permissible Loss PD 560 * mW
Storage Temperature Range TSTG -55 to +150 ºC
Notes: Derated at 5.6mW/ºC. above Ta = 25ºC; when mounted on a 74.2mm × 74.2mm × 1.6mm single glass epoxy substrate

Electrical Characteristics (Unless otherwise specified, Ta = 25ºC, VDD = 1.5V, f = 1kHz)

Parameter Symbeol Standard Values Units Remarks
Circuit Current (No Signal) IDD - 1.0 1.4 mA No load and no signal
Shutdown Current ISD - 3 9 µA SDB terminal = VSS
Mute Circuit Current IMUTE - 15 - µA MUTEB terminal = VSS, SE
Output Offset Voltage VOFS - 5 50 mV |VOUT1-VOUT2| and no signal
Maximum Output Voltage PO 70 85 - mW RL=8Ω,BTL, THD+N=1%
- 14 - mW RL=16Ω,SE, THD+N=1%
Harmonic Distortion THD+N - 0.2 0.5 % 20kHz LPF, RL=8Ω, BTL, PO=25mW
- 0.1 0.5 % 20kHz LPF, RL=16Ω, SE, PO=5mW
Output Noise Voltage VNO - 10 - µVrms 20kHz LPF + A-weight
Crosstalk CT - 85 - dB RL=16Ω,SE, 1kHz BPF
Power Supply Rejection Ratio PSRR - 62 - dB Ripple voltage = 200mVP-P Sine wave RL = 8Ω, BTL, CBYPASS = 4.7µF
- 66 - dB Ripple voltage = 200mVP-P Sine wave RL = 16Ω, SE, CBYPASS = 4.7µF
Input ‘H' Level VIH 0.7 - - V Applies to MUTEB and SDB terminals
Input ‘L' Level VIL - - 0.3 V Applies to MUTEB and SDB terminals