TLC272: Different Top Sides result in different outputs.

switch

Part Number: TLC272
Other Parts Discussed in Thread: TLC27M2, TLV2170, TLV3702, TLC3702, LMC6762

Tool/software:

Hi ti team,

Firstly, build an open-loop comparator using TLC272IDR, where the 2PIN of the IC is used as the sampling pin, the 1PIN of the IC is used as the output pin, and the 3PIN of the IC is the reference source with a voltage of 2V, and the power supply VCC is 4V. As shown in the figure below.

Secondly, currently, there are two Top Side situations when using TLC272IDR. For the same PCB board, different Top Sides result in different outputs. What is the cause of this phenomenon? After observation, TLC272IDR has undergone changes in DFAB. Is it caused by this change?As shown in the figure below.

Top Side is BCM，Channel 1 is IC 1PIN, and Channel 2 is IC 2PIN.

Top Side is 38K，Channel 1 is IC 1PIN, and Channel 2 is IC 2PIN.

over 1 year ago

0 Ron Michallick over 1 year ago

TI__Guru**** 167546 points

Hello Switch,

Yes due to the change. The change makes the TL2727 a little faster. I see the input (pin 2) is also changed.

Is the slower previous result required for desired operation in this application?

0 switch over 1 year ago in reply to Ron Michallick

Genius 3880 points

Hi Ron,

Getting faster will cause the circuit to cut off earlier, resulting in a smaller output current. Are there any methods to make the new version output more slowly?

0 Clemens Ladisch over 1 year ago in reply to switch

Guru 318700 points

You could try to slow down the R-C filter at the input, or to replace the chip with a slower opamp like the TLV2170 or TLC27M2, or to use actual comparators with a specified propagation delay like the TLC3702, LMC6762, or TLV3702.

0 switch over 1 year ago in reply to Clemens Ladisch

Genius 3880 points

Hi ，

Regarding the increased speed, the TLC727 PCN change document does not seem to mention this.

0 Ron Michallick over 1 year ago in reply to switch

TI__Guru**** 167546 points

Switch,

It is not mentioned directly. It does mention changes in design and process. This is a major change so a significant change can be expected.

Any change in performance will adhere to data sheet limits, minimum and maximums. Slew rate doesn't have any limits. For most applications faster is better. An ideal (perfect) op amp would be infinitely fast. So the change is towards perfect. Robust applications would work with a perfect op amp.

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TLC272: Different Top Sides result in different outputs.