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ISO1050 NMEA2000 12-15VDC - Regulator on Isolated Side

PaulR
Prodigy 145 points
Other Parts Discussed in Thread: ISO1050

What would be an appropriate regulator to use on the Isolated side of the ISO1050 CAN Tranceiver to regulate the line power down to the required 5V?

Is a heat sink required? (Given the duty cycle of CAN/NMEA2000 protocols and the voltage drop).

NMEA 2000 (Marine CAN) line provides 12-15VDC (NET-S), so I would hope there is no need to created an isolated power circuit, just regulate down the available line power.

(MCU on digital side is 3V3 and has its own power).

Paul

  • 0
    TI__Guru 55815 points

    Hi Paul,


    Any LDO with appropriate voltage & current ratings, low PSRR and good output accuracy should be fine for converting 12V-15V to 5V.

    Since the currents are really small you would not be needing any heat sink, assuming the regulator is only powering ISO1050.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 145 points
    That's what I was hoping, but the ISO1050 Icc2 Vcc2 Dominant supply current spec of max 73mA had me concerned (Datasheet section 6.5).
    I expected Dominant transmit to be shorting CANH=CANL with negligible current through supply pins.
    Paul
  • 0 in reply to PaulR
    TI__Guru 55815 points

    Hi Paul,

    Assuming VIN = 15V, VOUT = 5V, IOUTmax = 73mA, PD = 730mW. This is the worst case power dissipation, typically it would be around 520mW which is also neither continuous nor the idle / default state. You could probably use LDO in DPAK that should handle this power dissipation with ease.

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 145 points
    Thank you for clear and fast answers! (this is really appreciated given the frustration with some other suppliers).