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LT3070: About sequence/timing of VBIAS and VIN input

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Thread Summary

The user inquired about the correct sequence for starting the LT3070, specifically whether applying VIN before VBIAS is problematic. The final answer confirms that applying VIN first is acceptable as the LT3070 will remain off without BIAS. The support engineer recommends using the LT3070-1 instead, noting it has a different behavior during startup. The user will recommend the LT3070-1 to the customer.
AI Generated Content
Category: Hardware
Product Number: LT3070

Hi,

Our customer is using LT3070 now.

He said he heard about the sequence of LT3070 when starting operation that is first input VIN, second input VBIAS.

However, I think it is not good sequence because the inside opamp/comparator will be input signal without power supply by the instructure of LT3070.

Could you tell me the correct sequence for LT3070 start?

Best Regards,

Tomohiro

Edit Notes

I forgot type my name.
[edited by: Tomo-Kakehi at 12:20 AM (GMT -4) on 30 Jun 2025]
Parents
  • It is o.k. for your customer to apply IN first and then BIAS on the LT3070.  Applying IN first will not cause a problem because the LT3070 will be off with no BIAS.  The LT3070 still has a large inrush current even if BIAS is applied after IN.  I show that in the scope captures below.    It is better if your customer uses the LT3070-1 instead of the LT3070.  This post titled "LT3070 vs LT3070-1" explains the difference between the LT3070-1 and the LT3070.

    LT3070 LT3071 composite_1.png

       

Reply
  • It is o.k. for your customer to apply IN first and then BIAS on the LT3070.  Applying IN first will not cause a problem because the LT3070 will be off with no BIAS.  The LT3070 still has a large inrush current even if BIAS is applied after IN.  I show that in the scope captures below.    It is better if your customer uses the LT3070-1 instead of the LT3070.  This post titled "LT3070 vs LT3070-1" explains the difference between the LT3070-1 and the LT3070.

    LT3070 LT3071 composite_1.png

       

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