• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 642 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

PMP8740

PMP8740

anjana salgaonkar
Expert 1460 points
Other Parts Discussed in Thread: PMP8740

Hello Roberto,

I have few questions, Please help.

1) How variable fan RPM are achieved in PMP8740? Also what will be the voltage of pin (speed_reading P4.0). because in datasheet of fan the VFG signal voltage is mentioned as 13.8VDC max.

2) What is the purpose of circuit arround Q36, Q37, Q38, Q39 and J9, J10? is this circuit used only to lite-up yellow and green LEDs on J9, J10? because I can see U14 is used for CAN communication in PMP8740.

3) When (at what condition) Inrush relay signal is generated by controller? 

Thanks, 

Anjana 

  • 0
    TI__Expert 5875 points
    Hello Anjana,
    Here are the answers to your questions:
    1) Variable RPM is achieved in the PMP8740 by providing a PWM signal (generated with a timer of uC) on pin 1 of J1 connector. The part number of the fan is AUB0812VH-SP00, from Delta Electronics. The voltage on pin FG is pulled-up to 3.45V (Vcc of uC) by means of R26, therefore ranges 0.5V (0 logic) to 3.45V (1 logic). The value of 13.8V is the abs max. that the internal transistor can support, but in our case it doesn't play a role.
    2) You are right: the purpose of Q36...Q39 is only to drive the LEDs on CAN-bus connector and give visual indication that there is digital traffic on the bus, but if you don't need it, you can remove this section.
    3) The condition to close the inrush relay is that the input AC voltage is inside its acceptable range (set on the display, and typically 85VAC...265VAC), there is no alarm and a certain delay time has expired (in order to pre-charge the Boost PFC output capacitors, typically 50ms...200ms). I don't remember what was the timing but it's a fixed one in my design.
    Best regards,
    Roberto
  • 0 in reply to Roberto S.
    Expert 1460 points

    Thanks a lot Roberto.