Power Converter Responsive to Device Connection Status

1 . A primary controller, for a power converter, comprising:

a switch driver circuit configured to control an operating state of a first coil of a transformer for a power converter such that a second coil of the transformer provides an output voltage within a given voltage range; an

a current controller configured to:

receive a feedback signal; and

generate a modified feedback signal;

wherein, the switch driver circuit is further configured to:

receive the modified feedback signal; and

based on the modified feedback signal, control operating states of the first coil for a next switching cycle for the power converter.

2 . The primary controller of claim 1 ,

wherein, during a standby mode for the power converter, the given voltage range is between three and seven volts.

3 . The primary controller of claim 1 ,

wherein the current controller is further configured to:

determine whether an output current, communicated in the feedback signal, for a current switching cycle exceeds a first current limit for the power converter.

4 . The primary controller of claim 1 ,

wherein the current controller is further configured to:

determine a low dominant signal by selecting a lesser of an output current, communicated in the feedback signal, and a first current limit;

determine the modified feedback signal by selecting a greater of the low dominant signal and one of:

a first protection limit; and

a second protection limit.

5 . The primary controller of claim 4 ,

wherein the first protection limit is selected while an adaptive device is attached to the power converter; and

wherein the second protection limit is selected when the adaptive device is not attached to the power converter.

6 . The primary controller of claim 1 ,

wherein the current controller is further configured to:

receive the feedback signal from a secondary side of the power converter;

receive an applied voltage signal from a primary side of the power converter; and

modify the feedback signal based on the applied voltage signal.

7 . The primary controller of claim 6 ,

wherein the transformer includes a third coil;

wherein the feedback signal is representative of the output voltage; and

wherein, during a current switching cycle for the power converter, the applied voltage signal is induced in the third coil and is representative of a primary current through the first coil.

8 . The primary controller of claim 1 ,

wherein the current controller comprises:

a first resistor, having a first resistance; and

wherein the current controller is further configured to:

receive an applied voltage signal;

based on the first resistance, modify the applied voltage signal to provide a modified applied voltage signal; and

modify the feedback signal based on the modified applied voltage signal to provide a first modified feedback signal.

9 . The primary controller of claim 8 ,

wherein the first resistance is adjustable; and

wherein the current controller is further configured to:

adjust the first resistance to adjust the output voltage provided during a powered mode for the power converter.

10 . The primary controller of claim 8 ,

wherein the current controller is further configured to:

scale the first modified feedback signal to generate a scaled feedback signal.

11 . The primary controller of claim 8 ,

wherein the current controller further comprises:

a low voltage dominant bypass circuit configured to:

receive the first modified feedback signal;

receive a first current limit;

compare the first modified feedback signal with the first current limit; and

select and output as a low dominant signal a lesser of the first modified feedback signal and the first current limit.

12 . The primary controller of claim 11 ,

wherein the current controller further comprises:

a high voltage dominant bypass circuit configured to:

receive the low dominant signal;

receive one of a first protection limit and a second protection limit;

compare the low dominant signal with the received one of the first protection limit and the second protection limit;

select and output as the modified feedback signal a greater of the low dominant signal and the received one of the first protection limit and the second protection limit.

13 . The primary controller of claim 12 ,

wherein the current controller further comprises:

a selector configured to:

select the first protection limit while an adaptive device is connected to the power converter; and

select the second protection limit when the adaptive device is not connected to the power converter.

14 . The primary controller of claim 13 ,

wherein the selector is further configured to:

monitor the feedback signal; and

detect a connecting of the adaptive device to the power converter based upon changes in the feedback signal over two or more switching cycles for the power converter.

15 . A power converter, comprising:

a transformer comprising:

a first coil switchably coupled to a power source;

a second coil couplable to an adaptive device; and

a third coil configured to detect a primary current through the first coil and generate an applied voltage signal representative of an output voltage and an output current generated by the transformer over a current switching cycle;

a secondary controller configured to output, in a feedback signal, the output voltage and the output current for the current switching cycle;

a primary controller, coupled to the secondary controller, comprising:

a switch driver circuit configured to control an operating state of the first coil such that the second coil provides the output voltage within a given voltage range during a standby mode of operation for the power converter; and

a current controller configured to:

receive the feedback signal from the secondary controller;

modify the feedback signal to generate a modified feedback signal; and

provide the modified feedback signal to the switch driver circuit;

wherein the switch driver circuit, based on the modified feedback signal, controls the operating state of the first coil so that the output current for a next switching cycle does not exceed an output current threshold during operation of the power converter in at least one of the standby mode, a transition mode, and a powered mode.

16 . The power converter of claim 15 ,

wherein the current controller comprises:

a first resistor having a first resistance; and

wherein the current controller is further configured to:

receive the applied voltage signal;

based on the first resistance, modify the applied voltage signal to provide a modified applied voltage signal;

modify the feedback signal based on the modified applied voltage signal to provide a first modified feedback signal; and

scale the first modified feedback signal to generate a scaled feedback signal.

17 . The power converter of claim 15 ,

wherein the current controller further comprises:

a low voltage dominant bypass circuit configured to:

receive a first current limit;

receive a scaled feedback signal resulting from a scaled modification of the feedback signal based on the applied voltage signal;

compare the scaled feedback signal with the first current limit; and

select, and output as a low dominant signal, a lesser of the scaled feedback signal and the first current limit;

a high voltage dominant bypass circuit, coupled to the low voltage dominant bypass circuit, configured to:

receive the low dominant signal;

receive one of a first protection limit and a second protection limit;

compare the low dominant signal with the received one of the first protection limit and the second protection limit;

select and output as the modified feedback signal a greater of the low dominant signal and the received one of the first protection limit and the second protection limit; and

a selector, coupled to the high voltage dominant bypass circuit, configured to:

monitor the feedback signal;

detect a connecting of the adaptive device to the power converter based upon changes in the feedback signal;

select and output to the high voltage dominant bypass circuit the first protection limit [V IMIN1 ] while the adaptive device is connected to the power converter; and

select and output to the high voltage dominant bypass circuit the second protection limit when the adaptive device is not connected to the power converter.

18 . The power converter of claim 15 ,

wherein a nominal applied voltage signal generated during standby mode is less than a nominal applied voltage signal generated during powered mode.

19 . The power converter of claim 15 ,

wherein a ripple in the applied voltage signal during standby mode is greater than a rippled in the applied voltage signal during powered mode.

20 . A power converter, comprising:

a primary controller configured to control a switching cycle of a power converter such that:

during a standby mode of operation for the power converter,

an output voltage varies within a given voltage range;

the output current is less than a high threshold limit for the power converter; and

the output voltage has a larger ripple as compared to a ripple in the output voltage occurring when an adaptive device is connected and the power converter operates in a powered mode.