UVLO of D-CAP2 IC

Hi,

It is decided by the divider resistance on EN pin, please refer the threshold voltage of EN as below.

Shawn

Thank you for your answer!

In datasheet p.8 of TPS54228,
We think that VREG5 is LDO between Vin and UVLO.
We find the minimum input voltage if we can know the Vdo of VREG5 LDO to sense UVLO.
VREG5 typical Voltage(5.5V) + Vdo of VREG5 LDO = minimum input voltage?

We are worried that UVLO doesn't operate normally that input voltage drops.

Input voltage is 4.5~17V.
VREG5 is 5.5V.
Does UVLO not operate when Vin is 4.5V?
(Vin is lowewr than VREG5)


Best regards,

Takahiro Nishizawa

Hi,

VREG5 would be lower than 5.5V if VIN is lower than 5.5V.

Shawn

Thank you for your answer!

UVLO typical threshold is 3.75V(TPS54228 and TPS54628) and 3.8V(TPS54429).
Please tell us the input voltage when output voltage of VREG5 is less than UVLO threshold about each ICs(TPS54228 and TPS54628 and TPS54429).

Best regards,


Takahiro Nishizawa

Hi,

For TOS54628, the drop on the LDO is decided by the ouotput load, it is about 30mV with no load, and is about 120mV with 6A load. You can check the board by yourself.

Shawn

Thank you for your answer!

UVLO threshold of TPS54628 is 3.75V
Vdo of VREG5 is 120mV.
Minimum input voltage that TPS54628 can detect the UVLO normally is 3.87V (3.75+0.12).

Is this understanding correct?


About TPS54228 and TPS54229,
Is Vdo of VREG5 120mV?


Best regards,


Takahiro Nishizawa

hi,
Try to answer your question.
Simply, you can think from VIN to VREG5, it is an LDO(A mosfet under control). if VIN voltage is lower than voltage on VREG5, the current will flow from VREG5 CAP to VIN via MOSFET body diode. So, in your case, voltage on VREG5 will be higher than VIN about a diode volatage, ~0.5V. (in your case, if VIN is 0V, VREG5 will be no higher 0.5V )

Thank you for your answer!

Can these IC(TPS54228, TPS54229, TPS54628) detect the UVLO normally when Vin is 3.8V ?
Please tell us the minimum input voltage if UVLO can be detected with an input voltage lower than 3.8 V
Please tell us the minimum input voltage if these IC can not be sensed unless input voltage is higher than 3.8V.


Best regards,


Takahiro Nishizawa

Thank you for your answer!

For example,
UVLO threshold of TPS54202 is written with VIN.
But TPS54228, TPS54229 and TPS54628 are written with VREG5 about UVLO threshold.
We want to know the UVLO thresold in VIN instead of VREG5.

Can you define UVLO threshold with VIN about TPS54228, TPS54229 and TPS54628?

Best regards,


Takahiro Nishizawa

Hi,

Typically, "Minimum input voltage that TPS54628 can detect the UVLO normally is 3.87V (3.75+0.12)." is correct. You just need to sum of the drop voltage of LDO and VREG5 UVLO threshold voltage.

Shawn

Thank you for your answer!

Is Vdo of VREG5 120mV about TPS54228 and TPS54229?

Best regards,

Takahiro Nishizawa