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TPSI3050-Q1: In Zero-cross switching for solid-state relays of PSU ACp power on/off control

Meican Wu
Prodigy 10 points
Part Number: TPSI3050-Q1
Other Parts Discussed in Thread: TIDA-050058, TMUX1219, TPSI3050

Tool/software:

I have some questions  in design guide : TIDA-050058

1.  the  2 MOSFET will  be solid-state relay ?

2. the SEL in TMUX1219 , is come from other  like MCU io ?

3. the 5V and GND is the LV secondary side ?

4. in this application ,  whatever the timing of SEL , the EN @ ILOAD always turn on at zero point of AC ?

5. this application  cannot control turn off at zero pont of AC  right ?  if also want to turn off at zero point of AC , how to do the design?

6.  in the LOAD side , no mater for AC L or N TO CONNECT TO sw1/ sw2   point ?

7. what's the requirement for SEL signal ?

Thanks1

Meican.

  • 0
    TI__Prodigy 60 points

    Hello Meican,

    Meican Wu said:
    1.  the  2 MOSFET will  be solid-state relay ?

    Our solution, the TPSI3050, drives the external MOSFETs. Together, they all form a complete isolated Solid-State Relay

    Meican Wu said:

    2. the SEL in TMUX1219 , is come from other  like MCU io ?

    Yes, it can come from an MCU io

    Meican Wu said:

    3. the 5V and GND is the LV secondary side ?

    Yes, but also there is a different GND on the primary side as well.

    Meican Wu said:
    4. in this application ,  whatever the timing of SEL , the EN @ ILOAD always turn on at zero point of AC ?

    Yes, it will always turn on at zero point of AC

    Meican Wu said:
    5. this application  cannot control turn off at zero pont of AC  right ?  if also want to turn off at zero point of AC , how to do the design?

    Could you elaborate on why turning off at zero point AC is wanted? Is it a requirement?
    Our solution described in the TI design cannot turn off at zero point.

    Meican Wu said:
    6.  in the LOAD side , no mater for AC L or N TO CONNECT TO sw1/ sw2   point ?

    Hoping to clarify this question, it seems you're asking the implications of the AC load being grounded vs floating?

    Meican Wu said:

    7. what's the requirement for SEL signal ?

    SEL signal is recommended to be minimum 0V and maximum 5.5V

    Best Regards,

    Omer Gurbuz

  • 0 in reply to Omer Gurbuz
    Prodigy 10 points

    Thanks many replies. 

    the remain question :

    5.  turn on at AC zero point any time , that's good .  yes we would like also turn off at AC zero point which avoid at  high loading turn off will have spark or back EMF etc.  if this design donesnot  meet ?

    6. it means  no matter for AC LIVE/ NEUTRAL  direction  to connected in this application ?

    Thanks!

    Meican.

  • 0 in reply to Meican Wu
    TI__Expert 5366 points

    Hello Meican,

    Thanks for your reply here. The TIDA-050058 cannot turn off at the zero cross with how it is configured now. The detection in the off-state relies on a voltage measurement across the MOSFETs. Once the MOSFETs turn on, the voltage across becomes close to zero, and the comparator cannot detect the AC wave anymore. Will need to look into this more and let you know if we update the solution. It makes a lot of sense why turning off at the zero cross is important.

    Out of curiosity, what current levels are you expecting in your application?

    Meican Wu said:
    6. it means  no matter for AC LIVE/ NEUTRAL  direction  to connected in this application ?

    Yes, does not matter. The circuit is agnostic to being on the high-side or low-side.

    Best regards,
    Tilden Chen

    Solid State Relays | Applications Engineer