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36v 1a spi programmed power supply

archu vijay
Prodigy 200 points
Other Parts Discussed in Thread: TIPD138, OPA549, LF411, OPA2277, INA146, DAC8871, OPA140

TIPD138 - Test board for SPI programmable 16-bit, 36V, 1A Power Supply with Integrated Current Shunt - i am gone through the above paper provided by the ti design.i have some doubts regarding the input power supply.please help

on it the input power is positive and negative 40V .how can i get this power supply and what is the current rating of it?

can i increase the power rating to 10A using the same components and reducing the current limit resistor in opa549?

  • 0
    TI__Prodigy 10 points

    For board power, as described on page 2, there are four power rails required to power this design.

    • +40V for V+ of the OPA549 and LF411
    • -3V for V- of the OPA549 and LF411
    • +15V for V+ of the OPA2277, INA146, OPA140, and DAC8871
    • -15V for V- of the OPA2277, INA146, OPA140, and DAC8871

    We had used a Agilent (now Keysight) N6700 series supply to provide the four power rails. We had used a 60V 5A module for the +40V rail. There are several companies that make supplies that can provide the needed power for this design.

    As for scaling up the supply's output current, you are correct about having to change the current limit resistor, R5. However the OPA549 is rated to 8A output DC or 8Arms. Also the current shunt, R12, will need to be changed to higher power rating or lower resistance so it will not go over its power limit. However with higher current outputs may cause the OPA549 into thermal shutdown depending on heatsink used and operating condition. Large output currents cause large power dissipation in the OPA549's output stage, which will heat the part.

  • 0 in reply to Bill Eisenhower
    Prodigy 200 points

     Thank you for the reply.

    I want to design a precision power supply of (0-30)V, 5A  for that i would like to use an inbuilt power supply. Is it desirable if i use a 40V,5A unregulated power supply for +40v and  for -3V  a negative adjustable voltage regulator with 1a capability, and 7815 &7915 for generating +15V & -15V.

    Pls do reply

     

  • 0 in reply to archu vijay
    TI__Genius 10615 points

    Hello Archu,

     

    archu vijay said:
    Is it desirable if i use a 40V,5A unregulated power supply for +40v

    Most of the current will be supplied from the positive +40V rail. Typically when a power supply is sourcing its max. current, there is a significant max. voltage drop. This means that you need to make sure that the power supply can supply at least +35V at max. current.

    If you are using a 5A supply, the quiescent current consumption of the circuit will cause an endpoint error. A power supply with a max. current >5A would be desirable.

    archu vijay said:
    for -3V  a negative adjustable voltage regulator with 1a capability, and 7815 &7915 for generating +15V & -15V.

    These supplies should be sufficient.