Zetex Plc

Diodes Zetex Semiconductors Limited

Craig Maurice Taylor

Alan James Dodd

Rohit Arora

A switching regulator (-) supplies a controllable stable average current to a load (), such as series-connected light emitting diodes. A regulator controller () includes a hysteretic comparator () which controls a switch in the form of a transistor () for switching current into an inductor (). The comparator () has upper and lower thresholds. A first circuit comprising a fast current monitor () supplies a first signal to the comparator representing the instantaneous current in the inductor (). A second circuit (, and) supplies a second signal to the comparator representing an error between a desired regulator output and an actual regulator output.

Controller for switching regulator, switching regulator and light source

An amplifier circuit comprises a first amplifier stage controlling a second gain stage which is coupled between a voltage input node and an output node. A frequency compensating circuit is coupled between a compensating circuit node of the gain stage and a control input of the gain stage. The gain stage comprises first and second output devices arranged such that for a given gate voltage, the output current from the first device is greater than the output current from the second device. The output devices have a common source coupled to the input node and a common gate coupled to the first amplifier stage. The drain of the first output device is coupled to the output node and the drain of the second output device is coupled to the compensating circuit node with a resistance device connected between the two drains.

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Oldham, United Kingdom

Craig Maurice Taylor