Stereo 2-Vrms Line Driver and Headphone Amplifier

This is a 2V_rms Pop-Free stereo line driver with a stereo headphone driver designed to allow the removal of the output DC-blocking capacitors for reduced component count and cost. The project is based on the DRV604 chip which is ideal for single supply electronics where size and cost are critical design parameters. The project is capable of driving 2V_rms into a 5kΩ load and a clean 40mW into a 32Ω headphone with a single 3.3V supply voltage. Line and headphone outputs have ±8kV IEC ESD protection. The device has built-in shutdown control for pop-free on/off control. The DRV604 does not require a power supply greater than 3.3V to generate its 5.6V_pp output, nor does it require a split rail power supply. The DRV604 integrates its charge pump to generate a negative supply rail that provides a clean, pop-free ground biased 2V_rms output. This project is configured with single-ended header input connectors for analog input, headphones, and line output. The power supply is connected via a four-pin 2.54mm pin header.

Features

• Power Supply 3.3V (Range 3V To 3.7V)
• VSUP 3.3V Enables the Output
• Number of Channels 4
• Single-ended analog input and output
• Load Impedance: Line Min 5K Ohms
• Load Impedance: Headphone Min 32 Ohms
• Up to 2-Vrms Line Output
• Output Power: Headphone 40mW
• Dynamic Range > 103dB
• Eliminates Pop/Clicks
• Low Noise and THD DESCRIPTION– SNR > 109dB, Typical Vn < 7µVrms 20–20kHz,
• Single-ended analog input and output
• Shutdown Switch for Line and Headphone
• Power Sense UVP for Brown Out Protection
• Short Circuit and Thermal Protection
• PCB Dimensions 50.64 x 39.85 mm

Dual Stereo Line Driver

The Headphone stereo amplifier can also be used as Line Driver and has the same high output voltage capability as the Line amp when driving 5kΩ load impedances.

On/Off Sequence

For minimum click and pop during power on and power off, the DRV604 Enable inputs, pin 5 and pin 10, should be kept low.

Pop-Free Power Up

Pop-free power up is ensured by keeping the EN_LD and EN_HP and/or Ex_UVP low during power supply ramp up and down. The pins should be kept low until the input AC-coupling capacitors are fully charged before asserting the EN_xx pins high, this way proper pre-charge of the ac-coupling is performed and pop-less power-up is achieved.

Connections

• CN1: Pin 1,2 = VDD 3.3V, Pin 3,4 = GND
• CN2: Pin 1 = Line Input Left Channel, Pin 2 = GND
• CN3: Pin 1 = Line Output Left Channel, Pin 2 = GND
• CN4: Pin 1 = Line Output Right Channel, Pin 2 = GND
• CN5: Pin 1 = Line Input Right Channel, Pin 2 = GND
• CN6: Pin 1 = VSUP 3.3V, Enable/Disable for Pop free Output (3.3V=Enable)
• CN7: Pin 1 = Headphone Left Channel, Pin 2 = GND
• CN8: Pin 1 = Headphone Right Output, Pin 2 = GND
• CN9: Pin 1 = Headphone Left Channel Input, Pin 2 = GND
• CN10: Pin 1 = Headphone Right Channel Input, Pin 2 = GND
• SW1: Line Input Enable/Disable, Normally Enabled
• SW2: Headphone Enable/Disable, Normally Enabled
• D1: Power LED

Schematic

Parts List

Connections

Gerber View

Photos

DRV604 Datasheet

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