Ok, so I made the following circuit with some modifications:
I changed the value of R1 is 22.68K so the output voltage measures 5.06v. Everything is fine on paper and when using a probe to detect voltage, current, etc. In practice however, the voltage drops significantly when a load is attached (from 5.06v to 1.82v at times). I'll list the components I used. I'll be grateful if someone can help me figure out the culprit. I've tried substituting components that I thought were affecting the circuit without much in terms of results.
Components:
L: 10 uH (2.6A, 2.7A saturation, radial type)
Cc: 2200pF (2.2nF) 100V Ceramic
Rc: 24K 2 watt 5% metal oxide
Rfb1: 22K 2 watt 5% metal oxide + 680 2 watt 5% metal oxide in series (22.68K)
Rfb2: 7.5K 2 watt 5% metal oxide
Cin: 22uF 63V Aluminum Electrolytic
Cout: 22uF 63V Aluminum Electrolytic
D: 40V 3A Schottky 490mV@2A forward voltage
The only thing I have not tried so far was to replace the Cin and Cout capacitors with a different type of capacitor. There is a note in the LM2622 datasheet about using tantalum or ceramic capacitors in Cout. Could that be the only culprit? I am trying to connect a USB device to the Vout node. The USB device never powers on (the USB device is functional because I have a different circuit with which it works fine at 5.06v with the same USB socket used in this setup). The Vin node has adequate power for this USB device. So, what's the deal?
I changed the value of R1 is 22.68K so the output voltage measures 5.06v. Everything is fine on paper and when using a probe to detect voltage, current, etc. In practice however, the voltage drops significantly when a load is attached (from 5.06v to 1.82v at times). I'll list the components I used. I'll be grateful if someone can help me figure out the culprit. I've tried substituting components that I thought were affecting the circuit without much in terms of results.
Components:
L: 10 uH (2.6A, 2.7A saturation, radial type)
Cc: 2200pF (2.2nF) 100V Ceramic
Rc: 24K 2 watt 5% metal oxide
Rfb1: 22K 2 watt 5% metal oxide + 680 2 watt 5% metal oxide in series (22.68K)
Rfb2: 7.5K 2 watt 5% metal oxide
Cin: 22uF 63V Aluminum Electrolytic
Cout: 22uF 63V Aluminum Electrolytic
D: 40V 3A Schottky 490mV@2A forward voltage
The only thing I have not tried so far was to replace the Cin and Cout capacitors with a different type of capacitor. There is a note in the LM2622 datasheet about using tantalum or ceramic capacitors in Cout. Could that be the only culprit? I am trying to connect a USB device to the Vout node. The USB device never powers on (the USB device is functional because I have a different circuit with which it works fine at 5.06v with the same USB socket used in this setup). The Vin node has adequate power for this USB device. So, what's the deal?
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