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LDO 35V 1A WITH ON OFF CONTROL

STEVEN CHAN
Prodigy 60 points
Other Parts Discussed in Thread: LM317, UC1836, UC1834, UC2834, UC3834, UC2836, UC3836, UC2835, TPS7A47

HI THERE 

CAN YOU SUGGET A LDO WITH Vin MAZ  35V    Vout  6.3V   1A  ,   WITH ON/OFF CONTROL

THANK YOU~!

  • 0
    TI__Expert 5045 points

    Hello Steven,

    Something like the LM317 can do this conversion. Keep in mind that sourcing 1A across this differential will result in a lot of dissipation and heat up the device.

    ~ Aaron

  • 0 in reply to Aaron Paxton
    Prodigy 60 points

    Dear Aaron

    thanks for getting back .

    I need one with an enable pin ,  on/off control.

    It appears LM317 does not have enable pin ,right ?

    Steven

  • 0 in reply to STEVEN CHAN
    TI__Mastermind 33625 points

    Hi Steven,

    It will be difficult to design a linear regulator with 35V input and 6.3V output with 1A of current.  This will take more work than a normal linear regulator because of the amount of power being dissipated across the device.  The power dissipation across the LDO will be 1A*(35V-6.3V)=28.7W.  In a typical case, once you start dissipating 1-2W across an LDO you need to be aware of thermal dissipation.  You may want to consider a switching converter module, which we can help point you to the right engineering team if that is the case.  If you truly need the benefits of a linear regulator at these input and output voltages, you still have some options.  They all involve spreading the heat across more than 1 device.

    Option 1: Place a series dropping resistor in front of the LDO which will dissipate most of the power at 1A but will maintain 7.5V or so in front of the LDO. 

    Option 2: Assuming you need the performance of the LDO, use a switching converter module to convert 35V to something around 7.5V, then use an LDO to convert 7.5V to 6.3V

    Option 3: Use a linear regulator controller and locate a transistor in a large package that can dissipate the heat. Some of our linear regulator controllers include the UC1834, UC1835, UC1836, UC2834, UC2835, UC2836, UC3834, UC3835, and UC3836. 

    Let me know which option looks the best to you and we can discuss additional details from there.

    Thanks,

    - Stephen

  • 0 in reply to STEVEN CHAN
    TI__Expert 5045 points

    Hello Steven,

    If you want to try an LDO in this configuration, try the TPS7A47. You'll still want to be mindful of dissipation like Stephen Z mentioned. 

    ~ Aaron