I am having trouble shutting off the device using the CTRL pin.
I used the LT3465 model in the SWcadiii program and accompanying circuitry based on the app note for the part, i.e. 22uH inductor, etc. On the output, I use one LED with 4.3 ohms resistance to ground. When ground is applied to the CTRL pin, should I expect the part to shut off? The data sheet implies this, but I do not see what I think I should. I would expect very low input current to the part (probably u-amps) and negligible voltage/current to the output LED. Instead, the output appears on. I use a 5V input. In CAD, I have ramping the CTRL pin from 0 to supply voltage and at no point does the part appear to shut off.
I am seeing similar behavior on the bench. Am I missing something or doing something wrong? Is supply voltage an issue?
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Hello John,
The LT3465(A) works as promised in the datasheet. I don't know your circuit but a correct one like my example performs very well. The output current can be controlled from
0mA to about .2V/Rsense with a control voltage from 0 to 1V. Above 1V the current stays at .2V/Rsense.
Copy the text attached at the end of this message into a file named with a postfix ".asc", e.g. test.asc
This schematic file can be then opened with LTspice. Then press RUN , walk to the coffee machine to get a hopefully free coffee and when you come back the simulation is done.
Best regards, Helmut Moderator of the LTspice Yahoo group
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The LTspice schematic file test.asc .
Version 4 SHEET 1 880 680 WIRE -304 144 -304 80 WIRE -304 496 -304 224 WIRE -304 528 -304 496 WIRE -160 80 -304 80 WIRE -160 208 -160 80 WIRE -160 240 -160 208 WIRE -160 496 -304 496 WIRE -160 496 -160 304 WIRE -96 368 -96 336 WIRE -96 496 -160 496 WIRE -96 496 -96 448 WIRE -64 80 -160 80 WIRE -64 336 -96 336 WIRE 0 208 -160 208 WIRE 0 336 -64 336 WIRE 64 80 16 80 WIRE 64 128 64 80 WIRE 144 496 -96 496 WIRE 144 496 144 416 WIRE 224 128 224 80 WIRE 304 80 224 80 WIRE 336 80 304 80 WIRE 336 160 336 80 WIRE 352 336 288 336 WIRE 352 336 352 288 WIRE 352 384 352 336 WIRE 352 496 144 496 WIRE 352 496 352 464 WIRE 368 160 336 160 WIRE 368 288 352 288 WIRE 464 160 432 160 WIRE 464 288 432 288 WIRE 560 160 528 160 WIRE 560 288 528 288 WIRE 560 288 560 160 WIRE 656 80 336 80 WIRE 656 208 656 80 WIRE 656 496 352 496 WIRE 656 496 656 272 FLAG -304 528 0 FLAG -64 336 ctrl FLAG 304 80 out SYMBOL ind -80 96 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName L1 SYMATTR Value 22µ SYMBOL voltage -304 128 R0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL diode 368 176 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D1 SYMATTR Value LED SYMBOL diode 464 176 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D2 SYMATTR Value LED SYMBOL diode 432 304 M270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D4 SYMATTR Value LED SYMBOL diode 528 304 M270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D5 SYMATTR Value LED SYMBOL res 336 368 R0 SYMATTR InstName R1 SYMATTR Value 10 SYMBOL cap 640 208 R0 SYMATTR InstName C1 SYMATTR Value 0.22µ SYMBOL cap -176 240 R0 SYMATTR InstName C2 SYMATTR Value 1µ SYMBOL voltage -96 352 R0 WINDOW 3 -37 170 Left 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value PWL(0 1.5 .1m 1.5 .85m 0 1.25m 0 2m 1.5 ) SYMBOL PowerProducts\\\\LT3465A 144 272 R0 SYMATTR InstName U1 TEXT -328 -48 Left 0 !.model LED D(Is=1e-24 N=2 Rs=5) TEXT -328 -16 Left 0 !.tran 2m TEXT 112 -48 Left 0 ;Watch I(LED) and V(ctrl)
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