SBOU301A July   2023  – January 2024 LOG200

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  7. 2Hardware
    1. 2.1 Read this first: EVM Cleaning Guidelines
    2. 2.2 Input and Output Connections
    3. 2.3 Power Requirements
    4. 2.4 Jumper Information
    5. 2.5 Optional Photodiode Connections
  8. 3Hardware Design Files
    1. 3.1 Schematics
    2. 3.2 PCB Layout
    3. 3.3 Bill of Materials (BOM)
  9. 4Additional Information
    1. 4.1 Trademarks
  10. 5Revision History

2.1 Read this first: EVM Cleaning Guidelines

Logarithmic amplifier applications requiring picoampere range performance are very sensitive to PCB board contamination. Contaminants in the form of solder flux, oils and other impurities can form conductive paths over the sensitive PCB traces that allow small currents to leak from the input traces or other sensitive nodes, degrading performance. For best performance, make sure to keep the LOG200EVM as clean as possible. The following list shows best practices to clean the evaluation board and to help prevent the EVM from becoming contaminated:

  • Leakage currents from solder flux contamination can disturb the logarithmic amplifier's operation, specially at lower current levels. The LOG200EVM undergoes a standard cleaning protocol after the fabrication, soldering and assembly process prior shipping to customers, providing picoampere level performance. The EVM must be re-cleaned anytime devices are soldered into the PCB or modified near the logarithmic amplifier sensitive nodes, if the LOG200 U1 device is replaced, or if these input sensitive connections become contaminated by other means.
  • The recommended cleaning procedure requires access to an ultrasonic deionized (DI) water bath:
    • Place the EVM in the ultrasonic cleaner and fill with fresh deionized (DI) water.
    • Run the ultrasonic cleaner for 20 minutes at 45°C.
    • Remove all moisture from PCB.
  • If an ultrasonic bath is not available, then a manual cleaning procedure is possible:
    • Scrub contaminants from the top layer I1 and I2 inputs at top layer.
    • Use a toothbrush to gently scrub for 60 seconds. Focus on areas surrounding U1 I1, I2, VCM, and IREF inputs, R9, R13, R16, R17, R35, D1, input SMA connectors J4 and J6 and guard traces.
    • Scrub contaminants from the bottom layer around the diode D1 photosensor footprint and input SMA connectors J4 and J6.
    • Flush the scrubbed areas with fresh DI water, tilting the board to allow runoff to flow away from the input areas.
    • Remove all moisture from PCB.
  • When handling the EVM, always hold the board by the edges.
  • When not in use, place the EVM in ESD bag or other enclosure to prevent dust and other contaminants from settling on the board.