TLC2252A-Q1: diode from input to power supply

Mingkang Song

Expert 3280 points

Part Number: TLC2252A-Q1
Other Parts Discussed in Thread: LM2904-Q1, OPA310, TLV27L2-Q1, LM2904B-Q1

Hello, are there (clamping) diodes between input and power supply in TLC2252A-Q1?

Because our vdd is not always powered, other circuits will be affected if there is a path from input to vdd.

Thanks for your help and looking forward to your reply!

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 316440 points

The absolute maximum rating for V_I implies that the input voltages can be up to ±8 V, even with lower supplies.
But the absolute maximum rating for I_I implies that a current flows if the voltage is too large.

0 Mingkang Song over 1 year ago in reply to Clemens Ladisch

TI__Expert 3280 points

Does it means there is no diodes between input and power supply?

Up to ±8 V input voltage won't cause damage to the device, but it doesn't mean there is no voltage in the supplies now. Am I right?

Could you pls make sure if there is diode between input and power supply? Thanks! :)

0 Clemens Ladisch over 1 year ago in reply to Mingkang Song

Guru 316440 points

I am not a TI employee. But I'd guess that there are diodes, and that the V_I specification is wrong.

0 Mingkang Song over 1 year ago in reply to Clemens Ladisch

TI__Expert 3280 points

Thanks Clemens. Could you pls find someone who know the exact answer?

0 Gerasimos Madalvanos over 1 year ago in reply to Mingkang Song

TI__Mastermind 32746 points

Hello Mingkang,

I believe the absolute maximum ratings table shows the max/min input voltage at the specified maximum +/-8V supply. I can test a unit in lab tomorrow to confirm, but I believe there is a diode to both V+ and V-.

Best,
Jerry

0 Gerasimos Madalvanos over 1 year ago in reply to Gerasimos Madalvanos

TI__Mastermind 32746 points

Hello Mingkang,

Confirming this device has input diodes to V+ and V-. I appreciate your patience for this.

Best,
Jerry

0 Mingkang Song over 1 year ago in reply to Gerasimos Madalvanos

TI__Expert 3280 points

Thank Jerry. Would you pls recommend other low iq amp that doesn't have a diode between the input and the power supply?

0 Gerasimos Madalvanos over 1 year ago in reply to Mingkang Song

TI__Mastermind 32746 points

Hey Mingkang,

The lowest power device that we have that does not have a diode to V+, (note, there is still a diode to V-, but this is present in almost all op amps), is LM2904-Q1.

Our newest device with no input diode to V+ is OPA310, but it is not currently available in automotive version.

Best,
Jerry

0 Mingkang Song over 1 year ago in reply to Gerasimos Madalvanos

TI__Expert 3280 points

Thanks for your explanation.

May I ask if TLV27L2-Q1 has a diode between the input and the power supply?

0 Clemens Ladisch over 1 year ago in reply to Mingkang Song

Guru 316440 points

Yes, it has diodes. (Almost all opamps have diodes; devices like the LM2904-Q1 or OPA310 are a rare exception.)

0 Mingkang Song over 1 year ago in reply to Clemens Ladisch

TI__Expert 3280 points

Thanks Clemens. It's really helpful.

I'd like to update the requirements. Could you pls recommend op amps for me?

Parameters required for the op amp(Just choose one of the two):

The quiescent current is <150uA (under the full temperature range), and there is no clamping diode between the input port and the power supply.
VCC min≥5V, input to V- rail-to-rail, output rail-to-rail.
Q1 version
The quiescent current is <50uA (under the full temperature range), and it doesn't matter if there is clamping diode from the input port to the power supply.
VCC min≥5V, input to V- rail-to-rail, output rail-to-rail.
Q1 version

The price on the official website cannot exceed twice that of LM2904B-Q1. Thanks!

0 Gerasimos Madalvanos over 1 year ago in reply to Mingkang Song

TI__Mastermind 32746 points

Hey Mingkang,

I don't believe we currently have a good fit for that application in the current portfolio, but I have sent an email to you to discuss some devices in our upcoming portfolio.

Best,
Jerry

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TLC2252A-Q1: diode from input to power supply