Switching controllers and methods for loads

A system controller for providing at least an output voltage, the system controller comprising:

• a first controller terminal configured to receive an input voltage;
• a second controller terminal configured to receive a control voltage;
• a third controller terminal configured to output an output voltage;
• a fourth controller terminal biased to a predetermined voltage;
• a transistor including a gate terminal, a drain terminal and a source terminal, the drain terminal being connected to the first controller terminal, the source terminal being connected to the third controller terminal;
• a first resistor including a first resistor terminal and a second resistor terminal, the first resistor terminal being connected to the third controller terminal;
• a second resistor including a third resistor terminal and a fourth resistor terminal, the third resistor terminal being connected to the second resistor terminal, the fourth resistor terminal being connected to the fourth controller terminal;
• a third resistor including a fifth resistor terminal and a sixth resistor terminal, the fifth resistor terminal being configured to receive a first voltage related to the output voltage, the sixth resistor terminal being connected to the gate terminal of the transistor;
• a ramp voltage generator configured to generate a ramp voltage;
• a transconductance operational amplifier including a first amplifier terminal, a second amplifier terminal and a third amplifier terminal, the first amplifier terminal being configured to receive a second voltage from the second resistor terminal and the third resistor terminal, the second amplifier terminal being configured to receive the ramp voltage from the ramp voltage generator, the third amplifier terminal being connected to the sixth resistor terminal and the gate terminal of the transistor.