Hi,
I am currently working on developing a circuit that will control an external system using a PWM signal. The PWM signal will oscillate between -12V and 12V. To facilitate this, I have an external voltage supply rated at 12V with a maximum output of 1.5A.
I am utilizing an AZDelivery ESP-32 Dev Kit C V4 to generate the PWM signal. Additionally, I have a breakout board based on the MAX485 chip to convert UART to RS485.
My intention is to power both the ESP32 and the RS485 converter using the same voltage source. Both breakout boards can be powered with 5V. Therefore, I attempted to use a DC-DC converter to step down the 12V to 5V.
Here is the datasheet for the IC I am using: https://atta.szlcsc.com/upload/public/pdf/source/20160514/1463194849923.pdf
Please find attached the circuit diagram, which should be identical to the typical application circuit shown in the datasheet.
I have observed a peculiar behavior. When neither the MAX485 nor the ESP32 breakout boards are connected, I can measure 5V - which is perfect. However, when I attach one of these breakout boards, the voltage drops to approximately 1.7V.
I have tried changing the power supply and increasing the maximum current to 3A at 12V, but the behavior remains the same. It appears to be related to the drawn current. When I remove the breakout boards and replace them with a resistor, I observe similar behavior. With a high resistance (1MOhm), I measure a consistent 5V. With a 22k resistor, I measure 4.3V. And with a 10 Ohm resistor, I measure 0V.
As I am not an electronics expert, this situation is quite perplexing to me. I initially believed that a DC-DC converter would provide a stable voltage output, so this discrepancy is unexpected.
Any explanation is welcome
Thanks
I am currently working on developing a circuit that will control an external system using a PWM signal. The PWM signal will oscillate between -12V and 12V. To facilitate this, I have an external voltage supply rated at 12V with a maximum output of 1.5A.
I am utilizing an AZDelivery ESP-32 Dev Kit C V4 to generate the PWM signal. Additionally, I have a breakout board based on the MAX485 chip to convert UART to RS485.
My intention is to power both the ESP32 and the RS485 converter using the same voltage source. Both breakout boards can be powered with 5V. Therefore, I attempted to use a DC-DC converter to step down the 12V to 5V.
Here is the datasheet for the IC I am using: https://atta.szlcsc.com/upload/public/pdf/source/20160514/1463194849923.pdf
Please find attached the circuit diagram, which should be identical to the typical application circuit shown in the datasheet.
I have observed a peculiar behavior. When neither the MAX485 nor the ESP32 breakout boards are connected, I can measure 5V - which is perfect. However, when I attach one of these breakout boards, the voltage drops to approximately 1.7V.
I have tried changing the power supply and increasing the maximum current to 3A at 12V, but the behavior remains the same. It appears to be related to the drawn current. When I remove the breakout boards and replace them with a resistor, I observe similar behavior. With a high resistance (1MOhm), I measure a consistent 5V. With a 22k resistor, I measure 4.3V. And with a 10 Ohm resistor, I measure 0V.
As I am not an electronics expert, this situation is quite perplexing to me. I initially believed that a DC-DC converter would provide a stable voltage output, so this discrepancy is unexpected.
Any explanation is welcome
Thanks