L
Lostgallifreyan
Guest
Please can someone tell me if they can replicate this (in a default install
of LTspice)?
It's a differential amp set to gain of 0.25 (though unity or other shows same
effect). It drives the output hard to the supply rail and stays there! If you
replace the LT1213 model with the LT1215 (faster slew rate, twice supply
current but otherwise very similar IC), you get the expected standard
differential amplifier behaviour.
WHY?
I've looked to see if there's anything in the data sheet to indicate
why, and there isn't, they really look like they should both behave very
similarly here.
I've looked at LT's site to see if there's a later (or fixed) model but it's
the same, and LT1214 is also the same as 1213 with same error.
Copy below, save as LT1213 Test.asc...
Version 4
SHEET 1 880 680
WIRE 192 128 176 128
WIRE 240 160 224 160
WIRE 96 176 -48 176
WIRE 176 176 176 128
WIRE 192 176 176 176
WIRE -112 192 -128 192
WIRE 272 192 272 128
WIRE 272 192 256 192
WIRE -128 208 -128 192
WIRE -48 208 -48 176
WIRE 96 208 32 208
WIRE 192 208 176 208
WIRE 176 224 176 208
WIRE 224 272 224 224
WIRE 256 272 224 272
WIRE 256 288 256 272
WIRE -128 304 -128 288
WIRE -48 304 -48 288
WIRE -48 304 -128 304
WIRE 32 304 32 288
WIRE 32 304 -48 304
WIRE 176 304 32 304
WIRE 224 304 224 272
WIRE 224 304 176 304
FLAG -112 192 12V
FLAG 240 160 12V
FLAG 256 288 0
SYMBOL voltage 32 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5V
SYMBOL voltage -48 192 R0
WINDOW 3 -2 -39 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(0 5V 0 0 0 0.49ľ 1ľ)
SYMBOL res 176 144 R270
WINDOW 0 12 82 VTop 0
WINDOW 3 6 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 7.5K
SYMBOL res 80 192 R270
WINDOW 0 12 83 VTop 0
WINDOW 3 8 56 VBottom 0
SYMATTR InstName R2
SYMATTR Value 30K
SYMBOL res 80 224 R270
WINDOW 0 12 83 VTop 0
WINDOW 3 9 56 VBottom 0
SYMATTR InstName R3
SYMATTR Value 30K
SYMBOL res 160 208 R0
WINDOW 0 17 26 Left 0
WINDOW 3 19 79 Left 0
SYMATTR InstName R4
SYMATTR Value 7.5K
SYMBOL voltage -128 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value 12V
SYMBOL Opamps\\LT1213 224 128 R0
WINDOW 0 -19 64 Left 0
SYMATTR InstName U1
TEXT -162 130 Left 0 !.tran 1m startup
of LTspice)?
It's a differential amp set to gain of 0.25 (though unity or other shows same
effect). It drives the output hard to the supply rail and stays there! If you
replace the LT1213 model with the LT1215 (faster slew rate, twice supply
current but otherwise very similar IC), you get the expected standard
differential amplifier behaviour.
WHY?
I've looked to see if there's anything in the data sheet to indicate why, and there isn't, they really look like they should both behave very
similarly here.
I've looked at LT's site to see if there's a later (or fixed) model but it's
the same, and LT1214 is also the same as 1213 with same error.
Copy below, save as LT1213 Test.asc...
Version 4
SHEET 1 880 680
WIRE 192 128 176 128
WIRE 240 160 224 160
WIRE 96 176 -48 176
WIRE 176 176 176 128
WIRE 192 176 176 176
WIRE -112 192 -128 192
WIRE 272 192 272 128
WIRE 272 192 256 192
WIRE -128 208 -128 192
WIRE -48 208 -48 176
WIRE 96 208 32 208
WIRE 192 208 176 208
WIRE 176 224 176 208
WIRE 224 272 224 224
WIRE 256 272 224 272
WIRE 256 288 256 272
WIRE -128 304 -128 288
WIRE -48 304 -48 288
WIRE -48 304 -128 304
WIRE 32 304 32 288
WIRE 32 304 -48 304
WIRE 176 304 32 304
WIRE 224 304 224 272
WIRE 224 304 176 304
FLAG -112 192 12V
FLAG 240 160 12V
FLAG 256 288 0
SYMBOL voltage 32 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5V
SYMBOL voltage -48 192 R0
WINDOW 3 -2 -39 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(0 5V 0 0 0 0.49ľ 1ľ)
SYMBOL res 176 144 R270
WINDOW 0 12 82 VTop 0
WINDOW 3 6 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 7.5K
SYMBOL res 80 192 R270
WINDOW 0 12 83 VTop 0
WINDOW 3 8 56 VBottom 0
SYMATTR InstName R2
SYMATTR Value 30K
SYMBOL res 80 224 R270
WINDOW 0 12 83 VTop 0
WINDOW 3 9 56 VBottom 0
SYMATTR InstName R3
SYMATTR Value 30K
SYMBOL res 160 208 R0
WINDOW 0 17 26 Left 0
WINDOW 3 19 79 Left 0
SYMATTR InstName R4
SYMATTR Value 7.5K
SYMBOL voltage -128 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value 12V
SYMBOL Opamps\\LT1213 224 128 R0
WINDOW 0 -19 64 Left 0
SYMATTR InstName U1
TEXT -162 130 Left 0 !.tran 1m startup