DRV120: Start-up delay（tD) is out of spec.

Hi G.W.,

Is this test done on a DRV120EVM or is this with an original design?

How is the EN pin being triggered, MCU, push button, FET, etc.?

Best,

David

Hi David 

This is an original design.The EN pin being triggered by comparator.And the output of comparator is 3.3V.

Hi G.W.,

I'm curious if driving a highly inductive load could have some affect.

Is this test done with or without a load?

If with, could you measure the delay time without a load?

Best,

David

I try to measure the delay time without a load. but EN pin will pull down.it is normal?The output seems like no work. 

Hi David, here is another questian. why the tKEEP is not closely 75ms.

Hello,

Please allow me some time to look into this. 

Is the expected keep time 75ms?

Are you getting the expected hold current?

If possible, please share the schematic for review. 

Best,

David

Hello,

OK, i think the result should be closely 75ms. I no ture that the result if can be pass.And i get the expected hold current.Picture ablow is the schematic

I dont konw what is the load, you mean the solenoid of relay? or on the relay

Hello,

If possible, could you please measure the KEEP pin to see when it reaches 75mV?

At 75mV the current regulation ref voltage is switched from Vpeak to Vhold. 

Best,

David

Hi David

I tested the KEEP pin and the picture ablow is the result.Correct result should be 60.1ms?

Hi David,

I fund the picture in the datasheet.Could it be that the unit of time was mistakenly specified? no μs actually is ms?

Hi, 

Thank you for your post. Monday September 1st is national holiday in US. Please expect delay or please wait for our expert assignment on Tuesday US time

Hello,

Good find. I tested this in the lab on the DRV110 and found a delay time around 10ms. It does seem that the datasheet has a typo and should be ms not us. 

If this delay isn't suitable for your application, we do have newer devices that have shorter delays. Although this is the only "peak and hold" device in our portfolio, all of our independent half bridge devices can be used to peak and hold using PWM. 

Using DRV to Drive Solenoids (Rev. A)

I believe the DRV8220 data sheet, product information and support | TI.com would be good for your application. 

Best,

David

Thanks for your reply.I will recommend to the customer.And the keep time is normal ? Although it is much smaller than 75ms.