ionpak-thermostat/hardware/errata.md

1.3 KiB

Hardware errata

Rev 1

  • R307 needs more clearance from D400
  • Pins 1 and 12 of U502 need pull-downs
  • Pin 1 of U501 needs pull-up
  • D203 reversed polarity
  • R236 and R234 are swapped
  • Q301 needs to be NPN, change to BC817
  • increase R307 -> 3.3Kohm and increase R500 -> 33Kohm
  • C201: oscillates at 0 and 1nF, stable at 100nF
  • add clamp diodes to GND on op-amp outputs to ADC when op-amp has negative supply
  • R214 -> 7.5k
  • LM339PT is in TSSOP package. Change for SOIC P/N
  • GDT200 minimum firing voltage is too low
  • the relay model should be changed to 9001-05-00. 9001-05-02 is an undocumented normally closed variant.
  • D504 should follow the schematics in its datasheet
  • R502 should be connected to VCC
  • R502 -> 240 ohm
  • R234 -> 7.5k
  • Q104 -> DMN3404
  • R114 -> 470 ohm
  • R115 -> 4.7k
  • R227 -> 470 ohm
  • R228 -> 4.7k
  • review values of R226 and R113
  • C100 -> 100pF NP0 AVX
  • use crystal type recommended by the MCU datasheet
  • 22k FBI current resistor -> 10k?
  • add connector for OLED display?
  • enlarge holes to fit M3 screws comfortably
  • add 15M (TBC) resistor between A and FIL-
  • power U200 from a small negative voltage instead of GND
  • review choice of filament flyback output diode
  • invert LED position so that the Ethernet LED is closest to the connector
  • invert polarity of LEDs (Ethernet LED polarity cannot be programmed)