You are doing some cool stuff. Keep it up. I want to make a current limiter for a brushless motor circuit that operates on 24 to 48 volts. The max current I want to allow is 30 amps. How can I make such a device? Can I adapt this circuit to achieve it? Any help would be appreciated.
Thanks for explanation, but I tested this circuit to drive LEDs but once VSS input voltage goes up the current of LEDs goes up too, I used LM317 to drive same LEDs and it keep current limited as I need regardless the increase of input voltage !
@@LewisLoflin i have application where i have parallel loads. One load changes its current demand and it affects the other parallel loads. Will this circuit protect my other load from the current surge?
Be aware with a higher current output requires a higher current from the TL431. That relates to the HFE of the transistor. Don't exceed the TL431 current. Change RCL to 0.625 Ohms and make sure Q1 can handle (heat sink) 4A. See what happens.
So I found a spice model for the chip. Spice did confirm the 5 volts at the emitter. It looks like the 2.5v always appears from reference to anode. It looks like (based on spec sheet) that the ref voltage is supposed to always stay at 2.5 v. There is a max voltage spec for Vref of 6volts in the analog devices spec sheet for an equivalent part, the LT1431
With this schematic you can never get constant current, because anode current of TL431 pollutes main current flow. Anode curent changes with supply voltage and load resistance. In "current sink" connection, where load connected between supply+ and collector you can get relatively constant current only using termostable constantan/manganin shunt with Kelvin connection. Amen!
You are doing some cool stuff. Keep it up. I want to make a current limiter for a brushless motor circuit that operates on 24 to 48 volts. The max current I want to allow is 30 amps. How can I make such a device? Can I adapt this circuit to achieve it? Any help would be appreciated.
Thanks for explanation, but I tested this circuit to drive LEDs but once VSS input voltage goes up the current of LEDs goes up too, I used LM317 to drive same LEDs and it keep current limited as I need regardless the increase of input voltage !
Great stuff. Perfect combination of experiment and accident. Thank you.
accident, lol What do you mean?
Does this also work with transient current?
I don't understand the question.
@@LewisLoflin i have application where i have parallel loads. One load changes its current demand and it affects the other parallel loads. Will this circuit protect my other load from the current surge?
Congratulations from CYPRUS
What part to use if you need 4A limit?
Be aware with a higher current output requires a higher current from the TL431. That relates to the HFE of the transistor. Don't exceed the TL431 current. Change RCL to 0.625 Ohms and make sure Q1 can handle (heat sink) 4A. See what happens.
@@LewisLoflin The TL431 datasheet says "Sink-Current Capability: 1 mA to 100 mA
". Doesn't that mean it cannot handle 4A in any case?
@@johnaweiss Most of the current is through the pass transistor.
Thank you very much, Lewis! :)
I thought Vref has to always be at 2.5 volts. I do not know how 5 volts is on the ref pin on the last circuit.
So I found a spice model for the chip. Spice did confirm the 5 volts at the emitter. It looks like the 2.5v always appears from reference to anode. It looks like (based on spec sheet) that the ref voltage is supposed to always stay at 2.5 v. There is a max voltage spec for Vref of 6volts in the analog devices spec sheet for an equivalent part, the LT1431
Vref is the reference voltage from "Vref" pin to Anode pin, not always to GND, unless Anode and GND is connected.
great explanation.
With this schematic you can never get constant current, because anode current of TL431 pollutes main current flow. Anode curent changes with supply voltage and load resistance.
In "current sink" connection, where load connected between supply+ and collector you can get relatively constant current only using termostable constantan/manganin shunt with Kelvin connection. Amen!
That current is very small, but you are correct.
Cool !!
No entiendo ni madres míster 🙄😒