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# OPA454: High voltage OP with lower current consumption

Part Number: OPA454

Dear Sir/Ms.

My customer designed an OP circuit, he originally used OPA454, but found that the current consumption is too large, he wants to find a new OP, his specifications are as follows.

1. VCC +65V, -3.3V.
2. Output current 10mA.
3. not need big GBW.
4. The most important spec.  is that the current consumption is <3.2mA under the OP power supply state.
Does TI have an OP with this spec?

best Regards,

Kami Huang

• Hi Kami,

3.2mA is very little for a 100V OPAmp. And the heat dissipation is rather dominated by the 10mA output current.

Eventually, the circuit can be optimized for lower heat dissipation. Can you show a schematic?

Kai

• Hello Kami,

The only TI high-voltage op amp that comes close to meeting the application 3.2 mA maximum quiescent current is the OPA454. It's typical quiescent current is 3.2 mA, for VS = ±50 V, at TP = 25°C, RL = 4.8 kΩ to mid-supply, VCM = VOUT = mid-supply conditions. Under the same conditions a maximum of 4.0 mA is specified.

Observe that the quiescent current specification is with VS = ±50 V, a 100 V supply-to-supply difference. OPA454 datasheet Figure 18, Quiescent Current vs Supply Voltage, shows that the current is affected by the Vs level, and can be a little lower as the supply is decreased. That may allow the supply current to be decrease somewhat with (V+) 65 V, (V-) -3 V vs ±50 V. Although this lower quiescent current may be observed with the OPA454 in practice, TI makes no assurances that will be the case because that is not an assured datasheet specification.

All of TI's other high-voltage op amps have higher quiescent current and if the OPA454 doesn't meet the need then there isn't another model to suggest,

Regards, Thomas

Precision Amplifiers Applications Engineering

• Hello Kai,

I asked the customer for his schematic. Can I send you a private message? My customer doesn't want his schematic on the public web.

Best Regards,

Kami Huang

• Hello Thomas,

I got the customer for his schematic. Can I send you a private message? My customer doesn't want his schematic on the public web.

Best Regards,

Kami Huang

• Hi Kami,

Thom is out of the office today. Please send me or Thom a "friendship" request via E2E forum. Once we are able to establish a private communication, we may exchange the schematic information in private.

Per Thom's previous reply, the quiescent current in OPA454 may not lower much by a significant amount. If you are looking for lower quiescent current op amp, you may consider a different design approach or looking for a different amplifier.

Here are couple alternative options:

1. Use Bootstrapped amplifier configuration.

2. Use Complementary symmetry class AB amplifier to boost the output voltage

Option 1 may be easier to create than option 2 (less of issues) due to the low level of source/sink current at a load.

If you have additional questions, please let us know.

Best,

Raymond

• Hi Kami,

I am going to close this inquiry, since we have established communication via E2E private messaging.

If you have additional questions, please let us known.

Best,

Raymond