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TPS22810: On/Off time

Piet Vaes
Intellectual 410 points
Part Number: TPS22810
Other Parts Discussed in Thread: DRV104, TPL7407LA, ULN2003A, ULN2003B

Dear All,

I want to use the TPS22810 to switch on of off a buzzer with 4KHz signal on P0_5/RXTX and with PWM on P0_10/SWDIO to control a ventilator (see below). Therefore I need the fastest switch on and off time. How to setup the TPS22810. 

Best Regards,

Piet

  • 0
    TI__Genius 13300 points

    Hello Piet,

    Load switches are not recommended for PWMing applications. The signal with 4kHz would look more like a triangle wave and your PWM calculations would be inaccurate. I would recommend switching to a LSS device such as TPL7407LA or DRV104 which PWMing is supported. 

    Regards,

    Kalin Burnside

  • 0 in reply to Kalin Burnside
    Intellectual 410 points

    Dear Kalin,

    There is no stock of this part (TPL7407LA) in the TI-store, but are there similar parts available.. I need at least 5 drivers/PWM to control several outputs. The device which I want to drive/control are:

    2 ventilators (max 150 mA)

    1 buzzer 

    1 LedBar (max 1.5A)

    1 spare

    Best Regards,

    Piet

  • 0 in reply to Piet Vaes
    TI__Genius 13300 points

    Hello Piet,

    The LSS devices usually have a maximum of 1.5A when all channels are paralleled. You could use a device such as a single channel DRV10x for the LED bar, and then a LSS such as ULN2003A (or variations that may be in stock) for the ventilators and buzzer. Our high-side switches have maximum switching frequency of ~1kHz so I don't believe they would be of use here.

    Regards,

    Kalin Burnside

  • 0 in reply to Kalin Burnside
    Intellectual 410 points

    Dear Kalin,

    When I look to the datasheet (see below) every output can handle 600 mA (page 1) and we can combine them (page 7).

    1 Features

    • 600-mA Rated Drain Current (Per Channel)

    7.1 Overview

    Applications requiring sink currents beyond the capability of a single output may be accommodated by paralleling the outputs.

    My schematic

    Best Regards,

    Piet

  • 0 in reply to Piet Vaes
    TI__Genius 13300 points

    Hello Piet,

    You can see that when operating with numerous channels the recommended collector current falls depending on the duty cycle. If you're operating all channels at the same time having 1.5A on 3 combined channels would not work if the other channels are also active and could cause damage to the device if it exceeds the TJ max.

    Depending on your duty cycle and connecting the LED bar to the spare channel (4 paralleled channels)- it may help prevent the device from exceeding the ABS bounds.

    What duty cycle is expected for the LED bar?

    What is the max current for the buzzer? 

    In worst case scenario (all channels enabled at the same time) which channels would all be active at the same time?

    Regards,

    Kalin Burnside

  • 0 in reply to Kalin Burnside
    Intellectual 410 points

    Dear Kalin,

    Some answers

    I attached a document with the Power schedule

    Power Schedule.docx

    Best Regards,

    Piet

  • 0 in reply to Piet Vaes
    TI__Genius 13300 points

    Hello Piet,

    I will have a response for you by EOD 9/19.

    Regards,

    Kalin Burnside

  • 0 in reply to Kalin Burnside
    TI__Genius 13300 points

    Hello Piet,

    In every case with the LED bar setup with 4 channels the device would be operating within recommended operating conditions (also based on the maximums you mentioned earlier). 

    In terms of your original question: the ULN2003A option would not work as even with 4 channels tied to the LED bar with 1.5A max each channel would effectively take 375mA which would be above what's recommended on that device; however, ULN2003B could handle it. These are darlington pair devices (BJTs) instead of the MOSFET TPL7407LA device so you would have to take that into account (input current req for given load current). Currently it shows 67kU on ti.com. 

    Regards,

    Kalin Burnside

  • 0 in reply to Kalin Burnside
    Intellectual 410 points

    Dear Kalin,

    After some discussions and studies (internally) we decided to go for a multiple selection (partial assembly). Our schematic and PCB designer will design for use with the following:

    • ULN2003Bx {TSSOP (5.0x4.4) & SOIC (9.9x3.91)}
    • ULN2004Ax {TSSOP (5.0x4.4) & SOIC (9.9x3.91)}
    • TPL7407LAx {TSSOP (5.0x4.4) & SOIC (9.9x3.91)}

    Thanks for the advice

    Best Regards,

    Piet

  • 0 in reply to Piet Vaes
    TI__Genius 13300 points

    Hello Piet,

    You're welcome. If you have anymore questions please feel free to create a new thread.

    Regards,

    Kalin Burnside