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TPS2595: Need a recommended part with similar functionality for low-side control

David Dean
Expert 2315 points
Part Number: TPS2595
Other Parts Discussed in Thread: TPS22946, TLC59108

I am looking for a part like the TPS2595 but that I could use as a low-side switch.  The most important features are the adjustable current limit, microcontroller-friendly enable, and thermal regulation.  A low-side linear LED driver is more or less what I'm looking for, but most of what I have found tends to be lower current, less "smart", and requiring putting the load current through a sense resistor.

Is there any way to use the TPS2595 on the low side?  Or, can you recommend another component that is designed for low-side use (either an LED driver or other current) of similar package size and functionality?

  • 0
    TI__Guru 57737 points

    Hi David,

    TPS2595 cannot be used on the low side at the GND of the device needs to be at lower potential than Vin.

    I will assign this query to our low side switches team. Meanwhile you can have a look a out Low-Side switches portfolio here.

  • 0 in reply to Praveen GD
    TI__Genius 10652 points

    Hi David, 

    We don't have any lowside switches with current limit function. 

    What is your application? If you require current limit, whether fixed or adj, i strongly recommend to use a high-side solution because the low-side feature set is limited. 

    let me know if you have any other questions, otherwise please press the green button. 

    Best

    Dimitri

  • 0 in reply to dimitri james
    Expert 2315 points

    I basically need a linear LED driver.  I am realizing that perhaps an eFuse is not really what I want - the current limits are meant for fault detection, but not for actively limiting the load current as an LED driver would do.  Is that correct?

    Knowing this, are there any particular high side or low side parts you would recommend?

  • 0 in reply to David Dean
    TI__Genius 10652 points

    How many LEDs are you driving, what level of control do you need?

    If you are driving many LEDs and desire control on brightness for example an LED driver IC would be best, 

    If you simply want to turn on and off a few LEDs without frills then load switches would be best and I can make a recommendation on it.

    How many & How much current you will drive the LED(s) and will you drive them in parallel, series, etc?


    Best

    Dimitri

  • 0 in reply to dimitri james
    Expert 2315 points

    Most likely 2 LEDs, so a Vf of 6V.  Ideally I'd have the ability to drive just one LED (3V) if needed.

    I'd like PWM control for the brightness.

    My current circuit is simply a FET and resistor, which is arguably all I really need.  My main reason for looking for another solution is that I am very space constrained and would like to accomplish two things - first, a single component that can handle the switch and power dissipation in one, and second, a component with better thermal performance than a resistor - a small SMT package with a thermal pad often has better thermal conductivity than a much larger power resistor.  

    I could use a load switch and a resistor to set the current, but that's really no different than what I have now.  For this to be an advantage over my current circuit I'd need the load switch to also handle the current limiting (and thus power dissipating).  

  • 0 in reply to David Dean
    TI__Genius 10652 points

    David, 

    We have /some/ load switches that might work for you as long as your current is <500mA DC.

    I would recommend to look at TPS22946 and TPS22951

    They have either selectable or fixed current limits and are 5.5V max VIN parts. They are also available in much more compact packages than High-side switches which are available in HTSSOP leaded packages. 

    If you need higher current capability than this, a High side option or purpose-built LED driver IC is best. 

    Best

    Dimitri

  • 0 in reply to dimitri james
    Expert 2315 points

    My current is only about 250mA.  However, my max VIN is 10V, so I can't use these 5.5V parts.

    Can you recommend a high-side option (either load switch or LED driver or anything else) that can support a current-limited 250mA output and 10V VIN?

  • 0 in reply to David Dean
    Expert 2315 points

    To bring this back to the original component - can I use the TPS2595 as a high-side LED driver?  If I set the current limit (to, say, 500mA), connect LEDs to the output, and turn it on - will TPS2595 essentially work like a high-side linear LED driver?  I know that some eFuses or load switches will turn the output off when the current limit is hit, but this part looks like it will continue limiting the current until the thermal limit is reached.

  • 0 in reply to David Dean
    TI__Genius 10652 points

    David,

    While that part was not designed to be used as a linear LED driver, the topology is roughly equivalent to a linear driver and I think it could be used in the way you are describing.

    However, .I would still suggest to look at purpose-built LED drivers, apart from LED specific features they have higher current accuracy than the internal current limiting block of TPS2595 and other power switches which aren't designed for precision use, its the IC's airbag and wasn't intentended to operate against the ILIM full-time.

    Something, like TPS92630 cold probably work but if you need specific recommendations i will transfer this query to LED driver team as this is not my area of expertise. 

    Best

    Dimitri

  • 0 in reply to dimitri james
    Expert 2315 points

    Thank you.  Yes, please transfer this to the LED driver team.  The TPS92630 looks functionally suitable, but the large package size is a non-starter for my space-constrained layout.

  • 0 in reply to dimitri james
    Expert 2315 points

    Also, just to wrap up the questions about the eFuses - assuming my application is ok with the lower-precision current limit of the TPS2595, is it safe to use an eFuse if it is always in ILIM full-time?  Are there any further concerns other than the accuracy of the current limit?

  • 0 in reply to David Dean
    TI__Genius 10652 points

    The main issue you could run into thermal issues if you don't add sufficient external/series resistance as you will burn all the power in the FET, then the device will OTC and cycle on and off as it waits for over-temp to clear. 

    If you rely on ILIM to do this but do not add external resistance you will be burning nearly 5W in the FET channel and it will either not work or cook the IC.

    Anyways, I will transfer this over to LED driver Team. 

  • 0
    TI__Mastermind 22745 points

    Hi David,

         Could you share your current specification?(Current range, supply voltage range) We have some LED driver with current sinks which may be suitable for your application.

    BR

    Sean

  • 0 in reply to Sean Zhou
    Expert 2315 points

    Current range = 500mA max

    Voltage = 5 - 10V

  • 0 in reply to David Dean
    TI__Mastermind 22745 points

    Hi David,

        TLC59108 can support higher current when you connect multi-channel together and it is designed with current sinks structure which is the same as the low side switch.

    BR

    Sean