Hi Lillian,

I cannot quite see your schematic and waveforms as it is very low res. However, my guess is that since the minimum supply voltage is 2.7V, the device is not fully biased yet as it ramps up so the output flip flops and has an unknown output state during the power up stages before the supply reaches the minimum VCC. This is a common issue in older devices. However nowadays our newer comparators have an internal power on reset circuit that solves this issue by forcing the output to a known state during power on. See:

(1) [FAQ] How Power on Reset Comparators Simplify Designs - Amplifiers forum - Amplifiers - TI E2E support forums

What are your speed and power requirements? TLV7011 has a 260ns prop delay, slightly slower but has POR. 

Hi Lillian,

unfortunately, the scope plot and the schematic cannot be deciphered. Please post again.

As Chi has already mentioned this is fully normal. A normal chip does not work until a complete power-up plus a certain amount time to get the internal circuitry properly biased.

If the unwanted pulse has a smaller amplitude as when the supply voltage is fully supplied, then there's a simple remedy for "old" comparators: Add a transsitor switching stage which needs a minimum input voltage to switch. Here for a 5V system:

lillian_tlv3201.TSC

R1 can be replaced by a zener diode.

Of course, this circuit will shift the phase and you will need to swap the inputs of comparator.

Another remedy is to add some low pass filtering at the output of comparator to filter out the pulse, if the circuit allows. Or to combine the transistor inverter with the low pass filtering.

Kai

Hi Kai,

Thanks for your reply!

In addition, do you have any recommend of newer comparators that solves this issue and P2P with TLV3201?

Thanks 

Best regards

Lillian Liu

Lilian,

What are your speed and power requirements? TLV7011 has a 260ns prop delay which is slightly slower but has POR. 

Hi Chi,

Does TLV7011 P2P with TLV3201? I find there is a GND pin in TLV3201 but VEE pin in TLV7011. Can TLV7011 VEE pin connect ground?

Thanks 

Lillian