Hey Guys.
I have a little confusion about the TL072 opamp (DIP).
You see I am trying to make a charger for the SLA for my access controller.
I am not happy with the ones I see as they really does not do what it says. I have tried and it does not to switch to float. The Kit one I attached in the other SLA Battery thread.
So I am trying to make my own that does what I want.
The schema is attached. It is not complete but I ran the simulation and it works fine.
700mA Charging at 14.7V ( can be adjusted ). The charging current is sensed by the PIC ADC and switches on the float 13.85V ( can be adjusted ) when the Ibatt drops to 70mA.
Simulation works.
My concern is the TL072. It is wired across the Current sense resistor. OPAMP is used to sense the current draw to switch to float by PIC. The data says it works at single 5V rail. I needed a max 5V output as it is sensed by the PIC. The diode at opamp out put is a 5.1V zener for protection. I tried with main input (19VDC) but opamp ouput goes above 5V when sensing the current. At 5V Supply it won't. I can get a good OPAMP output variation (Voltage) from 0mA to 720mA (charger Current sensing).
The questions are.
1. Will the TL072 work at 5V Supply or do I need another Opamp.
2. The sensing voltage is differential but above IC's Vcc ( if at 5V Vcc ) but below 15VDC with in what the data says. So is this safe. I checked the data but since I have never used this OPAMP like this I like to confirm with some one more knowledge on differential amps and about this OPAMP running at minimum voltage.
I have a little confusion about the TL072 opamp (DIP).
You see I am trying to make a charger for the SLA for my access controller.
I am not happy with the ones I see as they really does not do what it says. I have tried and it does not to switch to float. The Kit one I attached in the other SLA Battery thread.
So I am trying to make my own that does what I want.
The schema is attached. It is not complete but I ran the simulation and it works fine.
700mA Charging at 14.7V ( can be adjusted ). The charging current is sensed by the PIC ADC and switches on the float 13.85V ( can be adjusted ) when the Ibatt drops to 70mA.
Simulation works.
My concern is the TL072. It is wired across the Current sense resistor. OPAMP is used to sense the current draw to switch to float by PIC. The data says it works at single 5V rail. I needed a max 5V output as it is sensed by the PIC. The diode at opamp out put is a 5.1V zener for protection. I tried with main input (19VDC) but opamp ouput goes above 5V when sensing the current. At 5V Supply it won't. I can get a good OPAMP output variation (Voltage) from 0mA to 720mA (charger Current sensing).
The questions are.
1. Will the TL072 work at 5V Supply or do I need another Opamp.
2. The sensing voltage is differential but above IC's Vcc ( if at 5V Vcc ) but below 15VDC with in what the data says. So is this safe. I checked the data but since I have never used this OPAMP like this I like to confirm with some one more knowledge on differential amps and about this OPAMP running at minimum voltage.
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