0
\$\begingroup\$

This TC7920 driver will be driving a piezo electric load which may behave like a capacitive load at certain frequencies. There is another IC TC8220 which is the same except it is not having the drain diodes like TC7920.Please let me know the use of these drain diodes. Can these ICs be relaced with each other for a piezoelctric load?

Another question is the use of damp signal? Is it just to pull the output to ground or any other use?

Link for TC7920: https://www.mouser.in/datasheet/2/268/TC7920_B080613-1532304.pdf Link for TC8220: https://www.mouser.in/datasheet/2/268/TC8220%20B080713-965140.pdf enter image description here

\$\endgroup\$
2
  • \$\begingroup\$ This is like a series RLC mode high Q Xtal resonance in high current. What would you expect during dead time? Then when middle pair FET are ON for some RC duration? Then after ? What is the impedance output? How is that good for pulse burst? \$\endgroup\$ – Tony Stewart EE75 Feb 15 at 18:51
  • \$\begingroup\$ You are looking too deeply into that. It's simply an high voltage H-bridge for resonant loads. Diodes are there for avalanche protection \$\endgroup\$ – Lorenzo Marcantonio Feb 16 at 7:43
0
\$\begingroup\$

The Supertex drivers (now Microchip IIRC) are quite strange beasts. In fact they are almost single-purpose chips.

The diodes are to protect the mosfets from the high voltage you have during resonance. In that 100V driver, you could have more than 200V on the transducer which would avalanche the fets (going over Vdsmax of 200V, and maybe doing damage). That diodes would add another 200V protecting the channel.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.