A power supply controller having a multi-function terminal. In one embodiment, a power supply controller for switched mode power supply includes a drain terminal, a source terminal, a control terminal and a multi-function terminal. The multi-function terminal may be configured in a plurality of ways providing any one or some of a plurality of functions including on/off control, external current limit adjustments, under-voltage detection, over-voltage detection and maximum duty cycle adjustment. The operation of the multi-function terminal varies depending on whether a positive or negative current flows through the multi-function terminal. A short-circuit to ground from the multi-function terminal enables the power supply controller. A short-circuit to a supply voltage from the multi-function terminal disables the power supply controller. The current limit of an internal power switch of the power supply controller may be adjusted by externally setting a negative current from the multi-function terminal. The multi-function terminal may also be coupled to the input DC line voltage of the power supply through a resistance to detect an under-voltage condition, an over-voltage condition and/or adjust the maximum duty cycle of power supply controller. Synchronization of the oscillator of the power supply controller may also be realized by switching the multi-function terminal to power or ground at the desired times.

Method and apparatus providing a multi-function terminal for a power supply controller

A D.C. to D.C. converter including a start circuit having a choke with a primary winding and a start winding. A portion of the input power is fed through a section of the start winding to the base of a switching transistor connected in series with the primary winding. The transistor is operated as a blocking oscillator by the start circuit and a voltage is induced across a secondary winding of the choke. The secondary voltage is rectified and fed to the control input of a pulse width modulator. In response to a predetermined level of the secondary voltage, the output of the pulse width modulator is coupled to the base of the transistor and the start circuit disabled. Current overload and transient voltage protection circuits are also included.

Direct current power converter with start-up and protection circuits

A pair of jaws moveable with respect to one another whether mounted in a hand held sealer or desk mounted sealer, compresses, heats, elongates, spreads and welds liquid filled tubing placed therebetween. Variants of the pair of jaws provide means for serially or simultaneously segmenting the tubing into a plurality of sealed compartments. The pair of jaws are electrically connected to a source of RF energy as the plates of a variable capacitor in an RF resonant circuit. The flow of RF energy across the pair of jaws, which energy heats the tubing and, in conjunction with mechanical pressure, makes the weld, is a function of timing and of the spacing between the jaws which spacing affects the degree of resonance of the RF resonant circuit. Simultaneous with the heating of the tubing, the configuration of the pair of jaws compresses the tubing placed therebetween and focuses the RF energy in a narrow swath across the tubing while simultaneously elongating and spreading the tubing at the swath to obtain a leak free weld, which weld is configured to provide for separation of the sealed compartments without tearing or rupturing the compartments.

Circuit for electro mechanical tubing sealer

Electrode mechanical tubing sealer

A circuit for use in a p.w.m. type power supply for increasing the efficiency thereof when the supply operates at low power levels. The circuit increases the efficiency by eliminating in a predetermined manner some of the p.w.m. pulses used to drive the power switching means of the supply.

Efficiency increasing circuit for switching power supplies operating at low power levels

THIS IS PROVIDED A HIGH POWER, CURRENT LIMITED, VOLTAGE REGULATED POWER CONVERTER SUITABLE FOR PRINTED CIRCUIT BOARD MOUNTING. A NORMALLY CLAMPED OSCILLATOR OPERATES AS A HIGH FREQUENCY SWITCHING CIRCUIT AND IT IS CONTROLLED BY AN ACTUATABLE OSCILLATOR CONTROL CIRCUIT. THE OPERATING FREQUENCY OF THE OSCILLATOR IS CONTROLLED SO AS TO PROVIDE A DC OUTPUT LEVEL WHICH IS MAINTAINED AT A PREDETERMINED LEVEL. UNDER A CLAMPED CONDITION, USUALLY AT NO LOAD, THE FREQUENCY REQUIRED TO GIVE THIS LEVEL IS THE LOWER OPERATING FREQUENCY LIMIT. A COMPARISON CIRCUIT CONTINUOUSLY COMPARES THE DC OUTPUT VOLTAGE WITH A PREDETERMINED LEVEL SET BY REFERENCE SETTING CIRCUIT. SHOULD THE DC OUTPUT VOLTAGE START TO FALL BELOW THE PREDETERMINED LEVEL, A VOLTAGE SIGNAL IS PRODUCED BY THE COMPARISON CIRCUIT. THIS VOLTAGE SIGNAL IS DIRECTED TO THE OSCILLATOR CONTROL CIRCUIT TO UNCLAMP THE OSCILLATOR TO OSCILLATE AT A FREQUENCY NECESSARY TO RESTOR THE OUPUT VOLTAGE TO THE PREDETERMINED VOLTAGE LEVEL.

Fieser Garland E

Papers

Variable load controlled blocking oscillator power converter