Littelfuse, Inc.

Ixys Corporation

Bret Ross Howe

Narasimham Patibandla

A relay circuit, including a solid state relay switch, connected to a first relay line and to a charging capacitor, and connected to a second relay line. The relay circuit may also include a solid state relay control circuit, coupled between the charging capacitor and the solid state relay switch. The solid state relay control circuit may include a voltage detection circuit, having an input coupled to an output of the charging capacitor, and having an output arranged to generate a LOW voltage signal when a voltage level of the charging capacitor is below a low threshold value. The solid state relay control circuit may also include a zero crossing circuit, coupled to the first relay line and the second relay line, and having an output to generate a clock signal when a zero crossing event takes place between the first relay line and the second relay line.

Solid state relay harvesting power from load by measuring zero crossing

A relay circuit may include a solid state relay switch, coupled to an external voltage line and to an charging capacitor; and a solid state relay control circuit, coupled between the charging capacitor and the solid state relay switch. The solid state relay control circuit may be arranged to: turn the solid state relay switch to an OFF state when a capacitor voltage of the charging capacitor falls below a low threshold value; and change the solid state relay switch from the OFF state to an ON state when the capacitor voltage increases above a high threshold value.

Solid state relay harvesting power from load by measuring stored energy

A current driver integrated circuit (IC) is coupled to control current flow through a diode. In one example, the diode is a Light Emitting Diode (LED) having an anode coupled to a supply node supplied by a battery and a cathode coupled to a drive terminal of the current driver IC. During operation the current driver IC is enabled and sinks an output current from the supply node, through the LED, through the drive terminal, and onto a ground node. As current flows through the LED, the battery is discharged. Changes in battery voltage cause an output voltage between the cathode of the LED and the ground node to change. Despite variations in output voltage, the current driver IC maintains a current level of the output current to be within five percent of a desired output current level across an output voltage range of at least 2V.

Current correction techniques for accurate high current short channel driver

A system for driving a multi-stage LED with low distortion and with current proportional to rectified input voltage is disclosed. In an exemplary embodiment, an apparatus includes LED groups connected in series to form an LED string having a first node, a last node, and intermediate nodes. The apparatus also includes current cells having inputs coupled to the nodes and outputs coupled to an output resistor. Each current cell selectively regulates current to flow between its respective input and the output resistor. The apparatus also includes a feedback circuit that generates a plurality of feedback voltages from a voltage level at the output resistor. When a selected current cell is enabled by a selected feedback voltage to regulate a selected current level from its respective input to the output resistor, upstream current cells are disabled by their respective feedback voltages.

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Irvine, CA, United States of America

Bret Ross Howe