Order Number LMT, LMT, LMT, LM78M05CT, LM78M12CT or LM78M15CT . be kept below +˚C in order to meet data sheet specifica-. LM78M05CT – Fixed Linear Voltage Regulator, , 3-Terminal, Positive, 10V. Add to compare. Image is for Technical Datasheet: LM78M05CT Datasheet. LM78M05CT datasheet, LM78M05CT pdf, LM78M05CT data sheet, datasheet, data sheet, pdf, Fairchild Semiconductor, 3-Terminal A Positive Voltage.
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Also the relay smells funny. John Birckhead 4, 4 However, I usually put a blocking Schottky diode in series with the output.
I have blown this specific part with the charge from large output decoupling capacitors when the input was shorted. Spehro Pefhany k 4 Is it possible the Fairchild LM has a different realisation as the linked data sheet mentions no such shunt diode nor any break down voltages? Further I measure in situ only R or so between the Vout and GND pins on the regulator both ways which is much less than what I would have expected.
So my questions are: Post as a guest Name. Bad news – You probably need the diode. The actual circuit is the one in this question: Sign up or log in Sign up using Google. Desoldered the regulator, all pin combinations with polarity measure within tolerance of a new one and it doesn’t smell. For example, reversed power connections. For now I think I’ll jurryrig a shunt diode on the pins as the board is already made. I’ll have to see how if that affects the rest of my circuit.
Jul 10 ’17 at 7: Review of my first ever PCB design for a watering control robot. The programming failed, and the target device has a “electronic” smell not present before. A Schottky from Vout?
Any other measurements I should make? Jul 9 ’17 at Email Required, but never shown. The has an emitter follower on the output stage, so you have probably let the smoke out.
They’re all pretty similar. Should I have had the DC power connected to the target?
For ICSP, you can add the diode but realize your programmer will have to power whatever is on the back side, or you can select the target’s vdd on some programmers.
I’m not sure how you damaged your target.
Sign up using Facebook. The output voltage has to be greater than the reverse breakdown of the B-E junctions in the regulator to cause damage, and 5V is not. I suggest proceeding with caution and looking for something else lm78m05c may have caused what appears to be significant damage.
LM78M05CT Datasheet PDF
For example, the TI datasheet specifically says: I’ve seen some versions of the regulator data sheets where the application notes recommend a diode from Vout to Vin in order to protect the device from burning out if the output voltage goes higher than the input. Also they mention short circuit protection. When I next plugged in the DC cord I got a spark from the ground terminal and there is a black residue from it on the solder mask of the DC plug and immediately unplugged the DC cord.
But those l,78m05ct can’t save the chip if it’s abused by putting 10V on the output with input grounded or 50V on the input.
LM78M05CT Datasheet(PDF) – National Semiconductor (TI)
There also has to be significant current flowing back both conditions are necessary for damage to occur. At this stage I think my move would be to replace thecheck any diodes for short circuits, power the board from a current-limited PSU and try again measuring the current draw and all supply voltages first! Hence I assumed it wasn’t necessary with their implementation.
LM78M05CT Datasheet(PDF) – TI store
That can cause issues if your circuit also datasheer a ground to earth somewhere, and very serious issues if the two are not nominally at the same potential.
Home Questions Tags Users Unanswered. It seems rather unlikely to me that this is the cause.