a lot of switching mode power supply design questions

1 ohm is the load or in series with coil? today I tried to drive a power laser diode but failed. is there a chip to do this work? 0-10A current source, ripple as low as possible?

The 1 Ohm is where th eload would go. I was showing the sort of topology not the full circuit.

If you change where the diode hooks to connect to the drain of the MOSFET it may do a little better.

Did you look at the ripple current in the R1.

losses.

Read the FAQs and detailed information about laser diodes I posted:

There are other links if you check the Wiki article.

Your laser diode is probably toast.

Paul

I modified it and deleted the C-L on the right side. If a 400khz, 22 uF of C2 are applied,ripple will be very low. however, I did a deadbug of this circuits, the transistor got hot at 400kHz! at 100 kHz it's okay. Is't caused by the switching power consumed on transistor?

Version 4 SHEET 1 880 680 WIRE -192 48 -624 48 WIRE -32 48 -192 48 WIRE 176 48 32 48 WIRE -192 96 -192 48 WIRE -624 208 -624 48 WIRE -592 208 -624 208 WIRE -448 208 -512 208 WIRE -288 208 -368 208 WIRE -192 208 -192 160 WIRE -192 208 -208 208 WIRE -16 208 -192 208 WIRE 176 208 176 48 WIRE 176 208 64 208 WIRE -624 288 -624 208 WIRE 176 352 176 208 WIRE -624 416 -624 368 WIRE 128 432 -16 432 WIRE 176 464 176 448 WIRE -16 528 -16 512 FLAG -16 528 0 FLAG 176 464 0 FLAG -624 416 0 SYMBOL ind2 -32 224 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName L1 SYMATTR Value 1000? SYMATTR Type ind SYMBOL schottky 32 32 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 41 34 VTop 0 SYMATTR InstName D1 SYMATTR Value MBRB2545CT SYMATTR Description Diode SYMATTR Type diode SYMBOL nmos 128 352 R0 SYMATTR InstName M1 SYMATTR Value IRF530 SYMBOL voltage -16 416 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(0 11.5 0 500n 500n 5?10? SYMBOL res -192 192 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 30 55 VTop 0 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL voltage -624 272 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value 11.8 SYMBOL res -496 192 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R2 SYMATTR Value 0.015 SYMBOL cap -208 96 R0 SYMATTR InstName C1 SYMATTR Value 100n SYMBOL ind -464 224 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 -1 52 VBottom 0 SYMATTR InstName L2 SYMATTR Value 3.9? TEXT -656 552 Left 0 !.tran 0 50ms 0ms 5ms TEXT -656 600 Left 0 ;k1 l1 l2 1.0

On May 28, 6:58 pm, MooseFET wrote:

losses.

much

Did you understand what those two parts did?

They allowed you to have zero ripple current in the LED.

IRL3803,

losses.

the

much

You might want to recheck this circuit, boss. Your capacitors are in Farads, and your inductors are in Henries. You won't see much happening in the simulator's 100mSec time frame.

RL

I just checked: C1 = C2 = 100uF

L1 = 12.2uH

L2 = 10uH

K1 = 0.9

On Sat, 31 May 2008 18:39:05 -0700 (PDT), MooseFET wrote:

This ia the file you posted.

Begin led.asc **************** Version 4 SHEET 1 880 680 WIRE -208 48 -480 48 WIRE 128 48 -208 48 WIRE 384 48 192 48 WIRE -208 96 -208 48 WIRE -480 208 -480 48 WIRE -480 208 -624 208 WIRE -384 208 -480 208 WIRE -208 208 -208 160 WIRE -208 208 -304 208 WIRE -16 208 -208 208 WIRE 176 208 64 208 WIRE 256 208 176 208 WIRE 384 208 384 48 WIRE 384 208 320 208 WIRE 384 272 384 208 WIRE -624 288 -624 208 WIRE 176 352 176 208 WIRE 384 384 384 352 WIRE -624 416 -624 368 WIRE 128 432 -16 432 WIRE 176 464 176 448 WIRE -16 528 -16 512 FLAG -16 528 0 FLAG 176 464 0 FLAG 384 384 0 FLAG -624 416 0 SYMBOL ind2 -32 224 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName L1 SYMATTR Value 12 SYMATTR Type ind SYMBOL ind2 400 368 R180 WINDOW 0 36 80 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName L2 SYMATTR Value 10 SYMATTR Type ind SYMBOL schottky 192 32 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D1 SYMATTR Value MBRB2545CT SYMATTR Description Diode SYMATTR Type diode SYMBOL nmos 128 352 R0 SYMATTR InstName M1 SYMATTR Value HAT2160H SYMBOL voltage -16 416 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(0 12 100u 100n 100n 8u 10u) SYMBOL cap 320 192 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C1 SYMATTR Value 100 SYMBOL res -288 192 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R1 SYMATTR Value 1 SYMBOL voltage -624 272 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value 12 SYMBOL cap -224 96 R0 SYMATTR InstName C2 SYMATTR Value 100 TEXT 536 248 Left 0 !k1 l1 l2 0.9 TEXT -658 552 Left 0 !.tran 0.1 end led.asc ***********************************

value C1 = 100 value C2 =100 value L1 = 12 value L2 = 10

I already know that adding E-6 to these values gives ~ functional units in the simulation time frame.

On Jun 1, 9:38 am, legg wrote: [.....]

You are absolutely right. In LTSpice the mu symbols are there. When I copy and paste from the text file they aren't.