Breaking News
Design How-To

Power Tip #3: Damping the input filter --- Part 1

More Related Links
View Comments: Newest First | Oldest First | Threaded View
Ishtiyaq
User Rank
Rookie
About negative input impedance
Ishtiyaq   8/6/2014 4:05:10 AM
Dear Robert Kollman,

I have read your article and found it really helpfull for myself. However, I would like to know one thing here.

While calculating negative input impedance of the converter you wrote:

Negative input impedance

This voltage-current line has a slope that essentially defines the dynamic impedance of the power supply. The slope of this line is the negative of the input voltage divided by the input current. That is, with Pin = V • I, we have V = Pin/I; and so dV/dI = –Pin/I2 or dV/dI ˜ –V/I.

This approximation is a bit of an over-simplification because the control loop impacts the frequency response of the input impedance. But many times, this simplification is good enough when current-mode control is involved.

Could you please explain that in the presence of Current-mode control, how this simple assumption is good enough?

Thank you very much.

Regards.

Flash Poll
Radio
LATEST ARCHIVED BROADCAST
EE Times editor Junko Yoshida grills two executives --Rick Walker, senior product marketing manager for IoT and home automation for CSR, and Jim Reich, CTO and co-founder at Palatehome.
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Times on Twitter
EE Times Twitter Feed