I am looking for help with this circuit. I need to build 35 of an LED dimmer circuit. I am trying to utilize the circuit in this link
https://www.allaboutcircuits.com/te...r-an-op-amp-output-for-higher-current-part-1/.
I used a LMC6482, rail to rail op amp and a TIP120 Darlington transistor as substitutes in the linked circuit. The op amp and transistor share the same 12 volt DC, 2.1 amp, Meanwell power supply. The LED array draws 1.61 amps at 9.8 volts when driven directly from a variable bench power supply. The op amp input is being driven from a 0-10 volt signal. The 0-10 volt signal originates from a remote 0-10 volt dimmer driver. The output tracks the input as expected so in general the circuit works great, except the TIP120 gets extremely hot. I have added the largest heat sink that I can fit to the TIP120 and still cannot control the heat. I have checked the current draw for the circuit while operating and it never exceeds 1.75 amps. What am I missing? Shouldn't the TIP120 suffice for this application? I have tried substituting a MJH6284 Darlington rated at 20 amps, but get the same results. Thanks in advance for any guidance!
https://www.allaboutcircuits.com/te...r-an-op-amp-output-for-higher-current-part-1/.
I used a LMC6482, rail to rail op amp and a TIP120 Darlington transistor as substitutes in the linked circuit. The op amp and transistor share the same 12 volt DC, 2.1 amp, Meanwell power supply. The LED array draws 1.61 amps at 9.8 volts when driven directly from a variable bench power supply. The op amp input is being driven from a 0-10 volt signal. The 0-10 volt signal originates from a remote 0-10 volt dimmer driver. The output tracks the input as expected so in general the circuit works great, except the TIP120 gets extremely hot. I have added the largest heat sink that I can fit to the TIP120 and still cannot control the heat. I have checked the current draw for the circuit while operating and it never exceeds 1.75 amps. What am I missing? Shouldn't the TIP120 suffice for this application? I have tried substituting a MJH6284 Darlington rated at 20 amps, but get the same results. Thanks in advance for any guidance!