LMZM33606: UVLO formula for 14V lockout

MohammedAl-Amin

Intellectual 540 points

Part Number: LMZM33606

Hello,

I was reading the datasheet for the LMZM33606 on page 21 Table 7 you have provided a UVLO for 10V and 15V.

But some of our batteries have minimum discharge at 15V and others at 13.5V.

I was hoping that we can implement a lockout at around 15.5-16V for one battery and for the other battery 14-15V.

But I was looking for a formula which I could use to work this out but there isn't one.

Or is the UVLO very accurate with tight tolerance to lock out at exactly 15V?

Would I be able to get help and advise on this.

Best regards

Mohammed

over 6 years ago

0 Jimmy Hua over 6 years ago

TI__Guru 50120 points

Hi Mohammed,

Table 7 in the datasheet provides a UVLO threshold resistor value selection for various common customer application requirements. I will look into the specifics of this and see if I can get you the equation used to generate this table.

Regards,
Jimmy

0 Jimmy Hua over 6 years ago in reply to Jimmy Hua

TI__Guru 50120 points

Hi Mohammed,

The UVLO threshold configuration is based on a resistor divider from Vin to set EN voltage to 1.2V.

As such the equation for UVLO threshold setting should be as follows:

RENT = 100k (typical)
RENB = (1.2 x 100k) / (VIN – 1.2)

Regards,
Jimmy

0 MohammedAl-Amin over 6 years ago in reply to Jimmy Hua

Intellectual 540 points

Thank you, Also, what is the tolerance for the UVLO, as we are thinking of using it for battery protection?

Best regards

0 Jimmy Hua over 6 years ago in reply to MohammedAl-Amin

TI__Guru 50120 points

Hi Mohammed,

Since the UVLO threshold is set by to resistors to achieve 1.2V at the EN pin, it is dependent on the resistor values. I haven't personally tested this myself but I'd expect that if you were using 1% resistor values then at minimum it would be 1% - 2% tolerance.

Regards,

Jimmy

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LMZM33606: UVLO formula for 14V lockout