SBOU229A August   2019  – April 2022 THS6222

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Features
    2. 1.2 EVM Specifications
  3. 2Power Connections
    1. 2.1 Split-Supply Operation
    2. 2.2 Single-Supply Operation
  4. 3Input and Output Connections
    1. 3.1 Bias Mode Control Pins
    2. 3.2 IREF Pin Connection
    3. 3.3 Optional VCM Pin Connection
  5. 4Board Layout
  6. 5Schematic and Bill of Materials
    1. 5.1 Schematic
    2. 5.2 Bill of Materials
  7. 6Related Documentation
  8. 7Revision History

2.2 Single-Supply Operation

When operating the THS6222RHFEVM in a single-supply configuration, the input common mode must be referenced to midsupply, V+/2. For single-supply operation, the input common mode is not at GND potential.

The THS6222 has an internal common mode buffer (see Section 7.1 of THS6222 datasheet); this buffer drives the common mode voltage to midsupply without external circuitry. The input common mode voltage is at the node between R1 & R2 in the THS6222RHFEVM schematic; this node is connected to TP1 as well as GND via R16 by default.

To enable a input common mode of V+/2, a board modification is required. Please remove R16 from the bottom side of the PCB: R16 holds the input common mode node, between R1 & R2, to GND. Setting the input common mode to GND for a single supply configuration will not properly operate the amplifier; there will not be device output on the THS6222RHFEVM if R16 is populated. The removal of R16 allows the internal common mode buffer circuit to work as intended during single-supply operation.

After removing R16 from the rear of the PCB, follow these steps for single-supply opeartion:

  • Connect both the V- connector and the GND connector to ground; apply the positive supply voltage to V+
  • Optionally use TP1 (red) to confirm the input common mode is at V+/2