• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Questions about a data-sheet for TC4420

Chilly

New Member
Thread starter #1
On page 9 "APPLICATIONS INFORMATION", on the output pin they're showing ( CL = 2,500pf ) and a polarized capacitor symbol. I'm trying to understand what CL represents. Capacitive Load?

And, on page 2 "Functional Block Diagram", it shows a dashed line with ( C = 38pf ) for an un-polarized capacitor on the input . I have some of these but haven't so far had any success locating a 2,500pf polarized.

<Mod added:>
http://ww1.microchip.com/downloads/en/DeviceDoc/21419D.pdf
 
Last edited by a moderator:

jpanhalt

Well-Known Member
Most Helpful Member
#3
Second question first:
upload_2018-1-18_5-10-26.png

That capacitor is not something you add, nor is it something that will replace the two diodes. It simply represents the "effective" capacitance of that design.

Page 9:
upload_2018-1-18_5-13-30.png


1) That representation is probably just "laziness" to use the common American symbol. If you check EAGLE, you will see there is no non-polarized US symbol for a capacitor.
2) As in the above instance, that is not a component you add. That represents an estimated (maximum?) gate capacitance for a large power mosfet being driven by the IC.

EDIT: In other words, that gate driver can be considered as a device that takes an input from a device that cannot provide much current ,e.g., an microcontroller, to switch a small capacitance and gives an output that can provide much higher current to get the same switching time for a much higher capacitance.
 
Last edited:

ronsimpson

Well-Known Member
Most Helpful Member
#5
It is much like a audio amplifier where some one drew a 4 ohm resistor on the output. (where a speaker goes)
The amp will work with 8 ohms or 16 ohm speakers, also. Will work with an open circuit.
Cl is max or typical load much like a audio amp has a typical load of 8 ohms.
 

Chilly

New Member
Thread starter #6
To everybody that answered, very informative and helpful. Thank you all! I'm having boards made and left a footprint for the CL capacitor. As far as the rest of those capacitors I'm assuming they would be used? The 0.1uf being probably non-polarized metal film and the 4.7uf being polarized.

View attachment 110357



A link to the "APPLICATIONS INFORMATION" would be helpful to save other members searching for it.

Les.
Thanks, I'll try to do better next time.
 

Latest threads

EE World Online Articles

Loading

 
Top