US Patent 9572224 Bleeder protection using thermal foldback

Thermally protected bleeder circuits for maintaining an input current of a power converter above a dimmer circuit holding current are disclosed. In one example, a bleeder control circuit may generate a bleeder control signal to control a bleeder current of the bleeder circuit based on an input current signal and a temperature signal. The bleeder control circuit may cause the bleeder current to be substantially equal to zero in response to the input current signal being greater than or equal to a reference signal, and may cause the bleeder current to be proportional to a difference between the input current signal and the reference signal in response to the input current signal being less than the reference signal. The reference signal may be constant for temperatures less than a threshold temperature, but may decrease with respect to increases in temperature for temperatures greater than the threshold temperature.