Digital control of quasi saturated fets for ripple control

A power supply system comprising:

• a converter configured to generate a drive signal based on a rectified input signal for powering a light source;
• a ripple control system comprising a voltage-controlled resistor (VCR) coupled to a secondary-side of the converter and configured to dynamically adjust a resistance of the VCR to compensate for ripples in the drive signal;
• a controller configured to sense an output voltage of the converter, to calculate a voltage drop across the VCR, and to generate a feedback signal to control the drive signal of the converter based on the sensed output voltage and the calculated voltage drop;
• a feedback resistor coupled between the VCR and a sense terminal of the controller;
• and
• a zener diode coupled between the feedback resistor and ground and configured to limit a voltage at the sense terminal of the controller,
• wherein the controller comprises:
• a second analog-to-digital converter (ADC) configured to sample a VCR voltage through the sense terminal.

A power supply system comprising:

• a converter configured to generate a drive signal based on a rectified input signal for powering a light source;
• a ripple control system comprising a voltage-controlled resistor (VCR) coupled to a secondary-side of the converter and configured to dynamically adjust a resistance of the VCR to compensate for ripples in the drive signal;
• and
• a controller configured to sense an output voltage of the converter, to calculate a voltage drop across the VCR, and to generate a feedback signal to control the drive signal of the converter based on the sensed output voltage and the calculated voltage drop,
• wherein the converter has a primary side and a secondary side electrically isolated from, and inductively coupled to, the primary side,
• wherein the ripple control system is electrically isolated from the primary side of the converter, and
• wherein the controller is configured to communicate the feedback signal to the primary side of the converter via an optocoupler.