Hardware/Mezzanine/audio AD-DA
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Audio AD/DA mezzanine board
This board has been developed as a low-cost replacement of the high-speed AD-DA board. It features:
Power supply
The supply from the connector is used to power the TL064 op amps. They can be powered between ±3.5 V and ±18V.
A TPS54227 DC/DC converter generates 6.5 V from the power supply and is followed by a 5 V regulator.
Hence, the minimal power supply range is about ±7 V.
Input range
The board input signals are brought to a first stage of differential op-amp circuits with:
- R15 = R17 = R16 = R18 = R36 = R38 = R37 = R39
- gain1 = R17 / R8 = R15 / R10 = R18 / R12 = R16 / R14 = R38 / R29 = R36 / R31 = R39 / R33 = R37 / R35
- pos_offset / pos_supply = R17 / R7 = R18 / R11 = R38 / R28 = R39 / R32
- neg_offset / neg_supply = R17 / R10 = R18 / R13 = R38 / R30 = R39 / R34
The ADC inputs range from 0 V to 5V.
The output of this first circuit is decoupled and brought to a second stage built around the in-circuit op-amp of the ADC. The gain of the second stage is:
- gain2 = R23 / R21 = R24 / R22 = R44 / R42 = R45 / R43
Output range
The DAC output signals are brought to differential op-amp circuits with:
- R15 = R17 = R16 = R18 = R36 = R38 = R37 = R39
- gain1 = R17 / R8 = R15 / R10 = R18 / R12 = R16 / R14 = R38 / R29 = R36 / R31 = R39 / R33 = R37 / R35
- pos_offset / pos_supply = R17 / R7 = R18 / R11 = R38 / R28 = R39 / R32
- neg_offset / neg_supply = R17 / R10 = R18 / R13 = R38 / R30 = R39 / R34
The DAC outputs range from 0 V to 5V.