SNOU184 November   2021 TLV3801

 

  1.   Trademarks
  2. 1Introduction
  3. 2Features
  4. 3EVM Specifications
  5. 4Recommended Equipment
  6. 5How to Make a TPHL Propagation Delay Measurement With Split Supplies
  7. 6Board Setup
    1. 6.1 Supply Voltage
    2. 6.2 Inputs
    3. 6.3 Outputs
  8. 7Layout Guidelines
  9. 8Schematic
  10. 9Bill of Materials

5 How to Make a TPHL Propagation Delay Measurement With Split Supplies

Note: Do not turn on power supply until all connections to the device are made to the board.
  1. Short VEE_OUT jumper to SYS_GND.
  2. Set one channel of the DC power supply to output a -2.5 V voltage and set its current limit to 100 mA. After ensuring that this channel is disabled, connect VEE_IN to this supply.
  3. Set one channel of the DC power supply to output a 2.5 V voltage and set its current limit to 100 mA. After ensuring that this channel is disabled, connect VCC to this supply.
  4. Ensure that cables connecting to IN+SENSE, OUT+, and OUT- are matched length and impedance. Perform any deskewing if no matched cables are available. For this setup, IN- is a DC voltage reference so the cables used for IN- and IN- SENSE do not need to be matched.
  5. On the signal generator output, set the function generator to produce a square wave output with 100 mVpp at 10-MHz, with a 0 V DC offset. This results in a 50 mV overdrive and 50 mV underdrive. Disable the signal generator output. Connect the signal generator output to IN+.
  6. Ground the inverting input, IN-, to ground to establish the threshold for the comparator at 0 V.
  7. Connect OUTP and OUTN to a 50-Ω terminated channel on the oscilloscope. Note that with capacitors C10 and C11 populated, the discharging and charging of these output capacitors will cause the output to be averaged.
  8. Connect IN+SENSE, to another 50-Ω terminated scope channel.
  9. Enable the VCC/VEE_IN power supply.
  10. Verify the total supply current is < 30 mA.
  11. Enable the signal generator.
  12. Monitor and verify the inputs from IN+SENSE and IN- is 0 V DC.
  13. Monitor and verify the outputs for OUT+ and OUT-.
Figure 5-1 TLV3801 EVM Propagation Delay with Latch Setup

Next is a scope shot capture of the inputs and outputs described in the propagation delay procedure. High to Low propagation delay is defined as when the signal generator input (IN+) reaches 0 V to when OUT- reaches 0 V. The propagation delay was measured at approximately 206 ps with the setup described.

Figure 5-2 Quick Start Example