TPS54678: TPS54678 UVLO accuracy

KKF

Part Number: TPS54678

Hi TI experts,

Do you have details about the accuracy of the enable falling threshold for TPS54678? The datasheet only specifies a typical value of 1.18V falling threshold (UVLO at EN pin) but no min/max values.
How much % of inaccuracy do I need to expect over full temp range?

Thanks and best regards,
KF

over 7 years ago

0 JohnTucker over 7 years ago

TI__Guru**** 191445 points

It is probably the same as the rising threshold. Let me check it. It may be a day or so.

0 JohnTucker over 7 years ago in reply to JohnTucker

TI__Guru**** 191445 points

The unofficial 6 sigma minimum is 1.1342 V at Vin = 2.95 V and Ta = -40 C.
The unofficial 6 sigma maximum is 1.2331 V at Vin = 6 V and Ta = 150 C.

0 Alexander Tschesno74 over 7 years ago in reply to JohnTucker

Prodigy 40 points

Hi John & other TI experts

Without deep comprehension of the physical causalities given by the internal current sinks I tried to calculate the impact of the 6 sigma values on Vstart and Vstop. I used the given formulas in the datasheet on Page 14 and the resistor values from our schematic R1=64k9 and R2=31k6. After several iterations in Excel I received following ranges for Vstart=3.9V-4.0V and Vstop=3.3V-3.5V:
VSTART 3.9
VEN_FALLING 1.2331 (at Vin = 6 V and Ta = 150 C.)
VEN_RISING 1.3
VSTOP 3.515
IP 0.0000007
IH 0.0000028

R1 =(F4*(F5/F6)-F7)/(F8*(1-(F5/F6))+F9) 64985.36683
R2 =(F12*F5)/(F7-F5+F12*(F8+F9)) 31933.96484

VSTART 4
VEN_FALLING 1.1342 (at Vin = 2.95 V and Ta = -40 C.)
VEN_RISING 1.3
VSTOP 3.3
IP 0.0000007
IH 0.0000028

R1 =(F4*(F5/F6)-F7)/(F8*(1-(F5/F6))+F9) 65707.15058
R2 =(F12*F5)/(F7-F5+F12*(F8+F9)) 31106.86494

Is my calculation plausible?

Regards
Alexander