THS3470: Using unequal split supplies

Keith Barkley

Part Number: THS3470

I am using the THS3470 as a pulse amplifier and because of the input common mode range of (Vee + 4) I have a -5 V bias on VEE and 50 V on Vdd. Are there any considerations I should be aware of.

I also see in a post a while back that the current monitor should be connected to Vmid when using unequal supplies. I am currently using the EVM which ties the Imon to ground via a 1K resistor. Will this cause issues monitoring the current?

15 days ago

+1 Ignacio Vazquez Lam1 15 days ago

TI__Mastermind 22680 points

Hi Keith,

Some of the more important considerations to be made are your functional digital pins and monitor pins like the I_monitor pin. The DGND pin is also very important to keep track of. This pin for example can be set to VEE up to VCC-12V. For the I_monitor pin with the resistor to ground I believe this would result in an issue if VCC is biased to 50V. Is the Vdd in your question a typo? If you are using our EVM it would be a safer option to populate the resistor divider going to VCC and VEE with resistors instead of having the 1kOhm to ground.

Best Regards,

Ignacio

0 Keith Barkley 14 days ago in reply to Ignacio Vazquez Lam1

Guru 43935 points

Yes, Vdd was a typo, I typed it without referring to the datasheet.

ETA:

I just read the data sheet, the Iout_monitor responds in 20 µs, which won't help much with my 3 µs pulse! Will I hurt anything by leaving in the 1K to ground?

+1 Ignacio Vazquez Lam1 14 days ago in reply to Keith Barkley

TI__Mastermind 22680 points

Hi Keith,

That is correct for some applications the speed of these features will simply not be fast enough. If you are skewing the supplies, I would still recommend changing the configuration as you could still damage the device by setting the resistor to ground.

Best Regards,

Ignacio

0 Keith Barkley 12 days ago in reply to Ignacio Vazquez Lam1

Guru 43935 points

Thank you!

0 Ignacio Vazquez Lam1 12 days ago in reply to Keith Barkley

TI__Mastermind 22680 points

Hi Keith,

No problem if you have any other questions or need clarification on how to implement this device please reach out.

Best Regards,

Ignacio

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THS3470: Using unequal split supplies