Dual voltage hot swap module power control
View Patent ↗A module hot swap circuit includes a low voltage-drop rectifier adapted to receive either positive or negative voltages of different absolute values. The rectifier is coupled to a power manager that provides dual startup/shutdown voltage thresholds and inrush current limiting. A detector prevents reverse current flow allowing the module to hold up during input voltage drop-outs.
1. A hot swap circuit, comprising:
a rectifier;
a controller coupled to the rectifier and operable:
to reduce a voltage drop of the rectifier;
to provide a first startup/shutdown voltage threshold when a voltage of a positive polarity is applied to the rectifier;
to provide a second startup/shutdown voltage threshold when a voltage of a negative polarity is applied to the rectifier; and
to limit inrush current; and
a detector coupled to the rectifier and the controller and operable:
to detect reverse current flow; and
to shut off the rectifier in response to detection of reverse current flow.
2. A hot swap circuit as defined in claim 1 , wherein the controller comprises a polarity sensing network coupled to the rectifier and operable to sense the polarity of the voltage applied to the rectifier.
3. A hot swap circuit as defined in claim 2 , wherein the polarity sensing network comprises a voltage divider.
4. A hot swap circuit as defined in claim 1 , further comprising a DC to DC converter coupled to the rectifier and operable to provide DC to DC conversion downstream of the rectifier.
5. A hot swap circuit as defined in claim 1 , wherein the controller is further operable to turn the rectifier back on after shutting off the rectifier in response to detection of a fault.
6. A hot swap circuit as defined in claim 5 , wherein the controller is operable to turn the rectifier back on after a predetermined delay after shutting off the rectifier in response to detection of a fault.
7. A hot swap circuit as defined in claim 1 , wherein the rectifier comprises a FET bridge.
8. A hot swap circuit as defined in claim 1 wherein the controller comprises a controller integrated circuit.
9. A hot swap circuit as defined in claim 7 , wherein the detector comprises a sense resistance and a comparator coupled to a first pair of FETs in the bridge.
10. A hot swap circuit as defined in claim 9 , wherein:
the controller comprises an inrush FET coupled to the sense resistance;
the controller is operable to sense current through the sense resistance and to adjust gate drive on the inrush FET to allow startup of a downstream DC to DC converter.
11. A method of hot swapping an electronic module, the method comprising:
applying an input voltage to a rectifier;
reducing a voltage drop of the rectifier;
providing a first startup/shutdown voltage threshold when a voltage of a positive polarity is applied to the rectifier;
providing a second startup/shutdown voltage threshold when a voltage of a negative polarity is applied to the rectifier;
limiting inrush current;
monitoring the rectifier for reverse current flow; and
if reverse current flow is detected, shutting off the rectifier.
12. A method as defined in claim 11 , comprising sensing the polarity of the voltage applied to the rectifier with a polarity sensing network.
13. A method as defined in claim 12 , wherein the polarity sensing network comprises a voltage divider.
14. A method as defined in claim 11 , further comprising performing a DC to DC converion downstream of the rectifier.
15. A method as defined in claim 11 , further comprising turning the rectifier back on after shutting off the rectifier in response to detection of a fault.
16. A method as defined in claim 15 , wherein the step of turn the rectifier back on comprises turning the rectifier back on after a predetermined delay after shutting off the rectifier in response to detection of a fault.
17. A method as defined in claim 11 , wherein the rectifier comprises a FET bridge.
18. A method as defined in claim 11 wherein the controller comprises a controller integrated circuit.
19. A method as defined in claim 17 , wherein the detector comprises a sense resistance and a comparator coupled to a first pair of FETs in the bridge.
20. A method as defined in claim 19 , further comprising sensing current through a sense resistance and adjusting gate drive on an inrush FET soupled to the sense resistance to allow startup of a downstream DC to DC converter.