Electronic control systems and methods
View Patent ↗An apparatus in an electronic control system allows two or three wire operation. A power supply can supply power to the enclosed circuitry in both two and three wire installations. Two separate zero cross detectors are used such that timing information can be collected in both two and three wire installations. Both zero cross detectors are monitored and are used to automatically configure the electronic control. Over voltage circuitry senses an over voltage condition across a MOSFET which is in the off state and turns the MOSFET on so that it desirably will not reach the avalanche region. Over current circuitry senses when the current through the MOSFETs has exceeded a predetermined current threshold and then turns the MOSFETs off so they do not exceed the MOSFETs' safe operating area (SOA) curve. Latching circuitry is employed to keep the protection circuitry in effect even after a fault condition has cleared. Lockout circuitry is used to prevent one protection circuit from tripping after the other circuit has already tripped from a fault condition. The protection circuitry output is desirably configured such that it can bypass and override the normal turn on and turn off impedance and act virtually directly on the gates of the MOSFETs. Preferably, the system has a high efficiency switching type power supply in parallel with a low frequency controllably conductive device.
1. A dimmer switch for controlling the amount of power delivered from a power source to a lighting load, the dimmer switch comprising:
a controllably conductive device connectable between said power source and said lighting load;
a control circuit for controlling said controllably conductive device, responsive to a user input signal representative of a predetermined amount of power to be delivered from said power source to said lighting load, said control circuit having a three-wire mode of operation wherein the dimmer switch operates with a neutral wire connection, and a two-wire mode of operation wherein the dimmer switch operates without a neutral wire connection; and
a detector circuit for detecting the presence of an output signal from a zero cross detector and causing said control circuit to switch from said two-wire mode of operation to said three-wire mode of operation upon detection of the presence of a neutral zero cross detection signal.