Electric door lock driver based on a current pulse generator and a switched mode current source with load-dependent output

A system for controlling an electric door lock comprising an electric lock coil, which comprises:

• a current pulse generator circuit, intended to be connected to a controller, to the electric lock coil and to a DC input voltage (VCC), and configured to generate a current pulse (Ipeak) to the electric lock coil during a peak time (Tpeak), when the controller sends a trigger signal;
• a constant current source intended to be connected to the controller, to the electric lock coil and to the DC input voltage (VCC), configured to generate an output voltage (Vout) greater than a voltage drop in the electric lock coil, being the constant current source configured to generate a constant current source (Ihold) to the electric lock coil, during a hold time (Thold), when the controller sends a trigger signal and after the current pulse (Ipeak), and comprising:
• a DC switched mode power source circuit, intended to be connected to the DC input voltage (VCC), and configured to receive the trigger signal and to output a DC output voltage (Vout);
• a low impedance resistor (RSENSE) intended to be connected at the output of the DC switched mode power source circuit;
• an amplifier, whose input is connected to the low impedance resistor (RSENSE);
• also intended to be connected to an external DD voltage generator configured to provide a DD voltage (VDD) and to a reference voltage generator configured to provide a reference voltage (VREF), proportional to the constant current source (Ihold) and to a resistance of the electric lock coil, and whose output is connected to the DC switched mode power source circuit to control the DC output voltage (Vout);
• and
• a rectifier which is connected to the output of the low impedance resistor (RSENSE) and is configured to ensure that the constant current source (Ihold) is applied after the current pulse (Ipeak);
• and wherein the constant current source (Ihold) is proportional to a resistance value of the electric coil Rcoil;
• and wherein the constant current source Ihold is lower than the current pulse Ipeak and, wherein the peak time Tpeak is in the range of milliseconds and the hold time Thold is in the range of seconds.