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TPS25947: TPS259474ARPWR - UVLO, OVLO Rising-Falling Tolerance

Bibin p s
Prodigy 55 points
Part Number: TPS25947


Are you having any other E-Fuse parts with less Over voltage and Under voltage threshold tolerance in falling and rising.
The currently using part TPS259474ARPWR having
UVLO Rising threshold  = 1.20
UVLO Falling threshold  = 1.09
OVLO Rising threshold  = 1.20
OVLO Falling threshold  = 1.09
The tolerance in rising and falling threshold is observed as 1.20 - 1.09 = 0.11. Please suggest any other part with same specification as TPS259474ARPWR and low rising and falling threshold tolerance.
  • 0
    TI__Guru* 79181 points

    Hi Bipin,

    That is hysteresis implemented in comparator. All our eFuses will have similar hysteresis. Why do you need lower hysterisis?

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 55 points

    Actually our concern with this E- Fuse is related to the Under voltage and overvoltage detection. We require Vin(UV) = 4.376V, Vin(OV) = 5.228V. When calculating this UV, OV voltage by considering the tolerance in the Rising and falling threshold voltages and the tolerance in the voltage dividing resistors(10% tolerance)  we observed some difference in the Over voltage and Under voltage.

    We calculated the best and worst case conditions in UV, OV by considering the OV(Threshold), UV(Threshold) hysteresis tolerance and resistor tolerances.

    Under voltage calculations
    Vin(UV) 4.3751 V
    R1 390K (10% Tolerance)
    R2 129.4K (10% Tolerance)
    Rising Falling
    worst case worst case
    R1 393.9 R1 393.9
    R2 128.106 R2 128.106
    Vuv th(Maximum) 1.223 Vuv th(Maximum) 1.116
    Vin(UV) 4.983 V Vin(UV) 4.547
    Best case Best case
    R3 386.1 R3 386.1
    R4 130.694 R4 130.694
    Vuv th(Minimum) 1.183 Vuv th(Minimum) 1.076
    Vin(UV) 4.677 V Vin(UV) 4.254 V

    We are getting UV voltage worst condition as 4.983V in rising and 4.254V in falling .

    Over voltage calculations
    Vin(OV) 5.228 V
    R3 470K (10% Tolerance)
    R4 140K (10% Tolerance)
    worst case worst case
    R3 474.7 R3 474.7
    R4 138.6 R4 138.6
    Vov th(Maximum) 1.223 Vov th(Maximum) 1.116
    Vin(OV) 5.411 V Vin(OV) 4.938 V
    Best case Best case
    R3 465.3 R3 465.3
    R4 141.4 R4 141.4
    Vov th(Minimum) 1.183 Vov th(Minimum) 1.076
    Vin(OV) 5.075 V Vin(OV) 4.616 V

    We are getting OV voltage worst condition  as 5.411V in rising and 4.938V in falling .

    This error difference will impact our actual design requirement.

  • 0 in reply to Bibin p s
    TI__Guru* 79181 points

    Hi Bipin,

    1. Can you use 1% resistor?

    2. OV falling worst is 4.938V which is above UV falling worst of  4.254V and also OV rise worst is above UV rise worst so functionality wise no concern. 

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 55 points

    Hi Kunal,

    We replaced the same resistors with 1% tolerance. Now we are getting results like this on the OV and UV.

    Vin(UV) =((Vuv*(R1+R2))/R2)

    Vuv(fall) = 1.09V
    R1= 390K
    R2= 129.4K
    Vin(UVfall) = 4.376 V(TYP)
    Expected change in Vin(UV) due to tolerance in Res and Threshold voltage
    Vin(UVris) = 4.678 V(MIN)
    Vin(UVris) = 4.98 V(MAX)
    Vin(UVfall) = 4.25 V(MIN)
    Vin(UVfall) = 4.54 V(MAX)

    Vin(OV) =((Vov*(R3+R4))/R4)

    Vov(ris) = 1.2V
    R3= 470K
    R4= 140K
    Vin(OVris) = 5.228 V(TYP)
    Expected change in Vin(OV) due to tolerance in Res and Threshold voltage
    Vin(OVris) = 5.076 V(MIN)
    Vin(OVris) = 5.412 V(MAX)
    Vin(OVfall) = 4.62 V(MIN)
    Vin(OVfall) = 4.94 V(MAX)

     

    We are having one concern on the Overvoltage and under voltage protection in our practical use case. The input to this E-fuse is from typical type-C adapter. Typical USB spec is 5V ±5%, so we might see 4.75V to 5.25V at turn on. The upper value may trigger OVris and the lower value may fail to satisfy UVris. 

    Please verify that our design can provide stable operation on the 4.75 to 5.25 voltage ranges.

  • 0 in reply to Bibin p s
    TI__Guru* 79181 points

    Hi Bipin,

    You can use more accurate resistors like 0.1%.

    Regards

    Kunal Goel