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TLV757P: TLV75733PDRVR

Jay Kevalramani
Prodigy 30 points
Part Number: TLV757P

Tool/software:

Hi everyone ,
We are using LDO TLV75733PDRVR in our project ,to get 3.3V as output voltage from 5V Input supply.
According to datasheet the LDO can withstand the Load of 1A ,but when the load line test was perform for load greater than or equal to 700mA it doesn't provide output 3.3V and stops working.
 I have attached the snapshot of our schematic for your reference.

  • 0
    TI__Expert 4660 points

    Hi Jay,

    Here your Vin= 5V, Vout= 3.3V, Iout= 0.7A ⇒ Power Dissipated (Pd) = (5-3.3)*0.7 = 1.19W

    RθJA for DRV = 100.2 °C/W

    Considering ambient temperature (Ta) of 30°C,

    Junction Temperature (Tj)= Ta + (RθJA * Pd)  ⇒ 30 + (100.2 * 1.19) ≅ 150°C

    Here you can see the part is operating out of the recommended operating temperature, and very close to the thermal shutdown temperature. I believe this is the issue here. 

    Would you be able to send a scopeshot with Vin, Vout, and Iout? Without seeing the response of the device, I cannot say for sure what the issue is.

    Regards,

    Bobby

  • 0 in reply to Bobby
    Prodigy 30 points

    Hi Bobby , 
    We understand this as thermal shutdown issue for confirming the same.
    When initially setting load as 700mA it works for few seconds and have breakdown as it reach to the Junction temprature higher then recommended (125°C)you ask for the Vin, Vout, and Iout , attaching the snapshot and short video for the same. 
    Please Confirm the issue is due to Thermal shutdown and also suggest what amendments could possibly be done to achieve 1A Load 
    Regards 
    Jay 

  • 0 in reply to Jay Kevalramani
    TI__Expert 4660 points

    Hi Jay,

    Thanks for the picture and video.

    I believe you do have an electronic load connected at output. 

    Will you be able to remove the electronic load, and connect a ~4.7ohm resistor (3.3V÷0.7A= 4.71ohm) as load to see if the part behaves the same way? I just want to make sure that LDO itself is not damaged.

    If you see this behavior still happening with pure resistive load, the most likely reason would be that the LDO is somehow damaged.

    Meanwhile, I will try to understand what exactly is happening in your video, and I will update you.

    Regarding your current situation, with your test conditions Vin= 5V, Vout= 3.3V, Iout= 0.7A, the TLV757P device is operating outside the recommended operating temperature, and the LDO may not work as intended.

    You will have to replace the device with another one that have a lower RθJA .

    Following is a link to the LDO products page on the TI website

    https://www.ti.com/power-management/linear-regulators-ldo/products.html#2277=20%3B70&451max=1%3B7.5&634min=-37%3B3.3&634max=3.3%3B125&sort=1130;asc&

    Here I have selected the filters such that products on this page will handle your output voltage and at least 1A load current. Various filters are available where you can select other parameters if required.

    If you are not able to find a part, give me the specs that you are looking for, and I will try to suggest you an alternative part. 

    Regards,

    Bobby

  • 0 in reply to Bobby
    Prodigy 30 points

    Hi Bobby , 
    Thanks for your quick and active response 

    I want you to know that LDO is not damage it works completely  fine at low load for any value less than 600mA . 
    Now I want to know that will there be any help if I connect the Pin 3 GND to the heat sink pin 7 , it will give any help in dissipating the heat and increase the number of vias. 
    I've attached the layout snapshot and shown the connection which I've mention above. 
    Regards 
    Jay

     

  • +1 in reply to Jay Kevalramani
    TI__Expert 4660 points

    Hi Jay,

    You should connect GND pin to thermal pad. In addition, for this device, you can connect NC pins (2 and 5) to GND as shown in the following figure from datasheet.

    However, even after connecting this, you are still operating outside the 'recommended operating temperature' and the LDO may not function as intended.

    Even at Iout=0.6A, even though the device appear to be working fine, 

    Junction Temperature (Tj)= Ta + (RθJA * Pd)  ⇒ 30 + (100.2 * ((5-3.3)*0.6)) ≅ 132°C. Here too the device is out of the 'recommended operating temperature' and the LDO may not function as intended all the time.

    I highly recommend changing to another device. 

    Regards,

    Bobby