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TPS25983: Schematic review eFuse

Matteo
Prodigy 115 points
Part Number: TPS25983


Hello,

could you please review this schematic?
Are there any errors or possibilities for improvement?
In particular, advice on C_dVdt (C86), R44, C_OUT, and is the pull-up for PG necessary?

In cascade, there is an SMPS and an LDO with C_IN equal to 2x 4.7µF and 10µF, respectively, followed by a motor driver (PWM 2 kHz) and other users. 

Thank you. Best regards,
Matteo

eFuse-wip_ver1.png

  • 0
    TI__Intellectual 2580 points

    Hi Matteo 

    Can you please provide the following details

    1. UVLO and OVLO set points

    2. Start up time 

    Best Regards

    Sailendra

  • 0 in reply to Sailendra Kumar
    Prodigy 115 points

    Hi Sailendra,

    1. as in the schematic, the resistor values for UVLO and OVLO give approximately:

    22.8 ≈ VIN(UV) = (1.2 * (R46 + R47 + R50)) / (R47 + R50)  
    25.2 ≈ VIN(OV) = (1.2 * (R46 + R47 + R50)) / R50 

    Expected VIN: 24 V DC ±5%

    2. Order of milliseconds — I don't have a requirement. CdV/dT (C86) = 3.3 nF.  Or do you mean something else?
    In which case is this parameter important?

    Thank you for your support. Best regards,
    Matteo

  • 0 in reply to Matteo
    TI__Intellectual 2580 points

    Hi Matteo 


    Matteo said:
    Order of milliseconds — I don't have a requirement. CdV/dT (C86) = 3.3 nF.  Or do you mean something else?
    In which case is this parameter important?

    This capacitor decides the slew rate of the output pin voltage. 



    Based on the required rise time of output pin , you need to get the required slew rate and putting that up in this equation gives you the capacitor value

    Regarding schematic 

    1. The PG pin is maximum rated to 7V and recommended is 6V. But in schematic it is connected to 24V 

    You are advised to follow below connections for PG pin




    Best Regards

    Sailendra

  • 0 in reply to Sailendra Kumar
    Prodigy 115 points

    Hi Sailendra,

    Thank you for your reply.

    From C_dVdT = 4600 / SR
    SR = 4600 / 3300pF = 1,39 ms

    As I said, I currently don't have a requirement,  what capacity value do you recommend?

    The PG pin has its pull-up in the schematic but it's not connected yet. As you can see, there's no label on the connection. I absolutely won't connect it directly to 24 V for the reasons you mentioned. But can I connect it to 3.3 V? The 3.3 V is generated by an SMPS in cascade. So as long as the 24 V output is not present, I don't even have the 3.3 V for PG.

    Thank you, best regards,
    Matteo

  • 0 in reply to Matteo
    TI__Intellectual 2580 points

    Hi Matteo

    Yes you can connect PG pin to 3.3V through a pull resistor .

    Matteo said:
    what capacity value do you recommend?

    Yes , you can get the value using the design calculator in the website by filling the experimental conditions

    Best Regards

    Sailendra