Hello everyone,
I have an ULN2003 transistor driver array to control different relay coils, the ULN2003 is controlled by a MCU. For coil supression I decided to use a 4148 diode with a 6.8V zener diode. The attached schematic is just a design, it is not a real PCB in which I could measure.
Initially, the PCB in which I am making tests doesnt have the LDO as far as the DCDC supplies 3.3VDC. In my new design that I attached I increased the output voltage from the DCDC to 5V willing to use a low high SRR LDO to power the most sensitive ICs like the MCU.
The fact is that within the PCB where Im making tests (everything works at 3.3V) is working well but I am concerned about some transients I measured and that spreading through the power net (I guess). I want the circuit to be very reliable as far as I am going to implement a bluetooth IC also besides the MCU and I dont think that the measured transients are good any sensitive IC
This shows all transients in I/O pin of the MCU while de-energizing a relay. Note that this I/O pin of the MCU is not connected directly to the relay or the power rail, it is just a normal I/O pin
This shows a zoomed transient, how wide it is, it lasts 129nanoseconds
How would you supress this transients? I think that even if everything works well while testing, it will damage the circuit somehow anytime
I have an ULN2003 transistor driver array to control different relay coils, the ULN2003 is controlled by a MCU. For coil supression I decided to use a 4148 diode with a 6.8V zener diode. The attached schematic is just a design, it is not a real PCB in which I could measure.
Initially, the PCB in which I am making tests doesnt have the LDO as far as the DCDC supplies 3.3VDC. In my new design that I attached I increased the output voltage from the DCDC to 5V willing to use a low high SRR LDO to power the most sensitive ICs like the MCU.
The fact is that within the PCB where Im making tests (everything works at 3.3V) is working well but I am concerned about some transients I measured and that spreading through the power net (I guess). I want the circuit to be very reliable as far as I am going to implement a bluetooth IC also besides the MCU and I dont think that the measured transients are good any sensitive IC
This shows all transients in I/O pin of the MCU while de-energizing a relay. Note that this I/O pin of the MCU is not connected directly to the relay or the power rail, it is just a normal I/O pin
This shows a zoomed transient, how wide it is, it lasts 129nanoseconds
How would you supress this transients? I think that even if everything works well while testing, it will damage the circuit somehow anytime