F
futrtrubl
- Jan 1, 1970
- 0
I have the below buck converter..
http://www.edowner.net/soft-start.gif
Now I'm trying to figure out how quickly or slowly I should soft start
it.
The only way I could think of doing it is to see how long it would
take to charge the capacitor with my "excess" current. At full blast
my load will require 3.5Amps and my power supply can supply 4.5Amps
giving me 1Amp to use in charging the capacitor.
Total charge Qon fully charged capacitor = C*V = 1.8e-3 * 24 = .0432
Coulombs.
Q= I * t, t= Q / I, so t= .0432 / 1 = 0.0432 seconds
So I was thinking of ramping up to 100% duty linearly over that 43
milliseconds ie. about 2%/ms.
Is there a better way to calculate soft start time for my application?
Info not in schematic, power supply is rated at 24V 4.5A, tiger power
model SYM04-3 (btw, I'm still looking for more information or
datasheet on this if anyone knows where), FET is rated at 16A
continuous, inductor at 8 Arms and capacitor at 3.7Amps ripple. The
load is resistive (a peltier cooler) with an R of around 6.9 Ohms.
Switching frequency not yet set, could use some recommendations.
Edward
http://www.edowner.net/soft-start.gif
Now I'm trying to figure out how quickly or slowly I should soft start
it.
The only way I could think of doing it is to see how long it would
take to charge the capacitor with my "excess" current. At full blast
my load will require 3.5Amps and my power supply can supply 4.5Amps
giving me 1Amp to use in charging the capacitor.
Total charge Qon fully charged capacitor = C*V = 1.8e-3 * 24 = .0432
Coulombs.
Q= I * t, t= Q / I, so t= .0432 / 1 = 0.0432 seconds
So I was thinking of ramping up to 100% duty linearly over that 43
milliseconds ie. about 2%/ms.
Is there a better way to calculate soft start time for my application?
Info not in schematic, power supply is rated at 24V 4.5A, tiger power
model SYM04-3 (btw, I'm still looking for more information or
datasheet on this if anyone knows where), FET is rated at 16A
continuous, inductor at 8 Arms and capacitor at 3.7Amps ripple. The
load is resistive (a peltier cooler) with an R of around 6.9 Ohms.
Switching frequency not yet set, could use some recommendations.
Edward
