Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Nxp B.v.

Hendrikus Johannes Janssen

Paul R Veldman

Tobias Georg Tolle

Johan Christiaan Halberstadt

Arjan Van Den Berg

Abraham L Melse

Hendrikus Johannes Jacobus Domensino

Hendrik Jan Boswinkel

An electronic circuit has an output driver (DRV) for providing a driving signal (U). The output driver has a transistor (T) with a first main terminal, a second main terminal and a control terminal coupled to receive a control signal (V), a power supply terminal (V), an output terminal (OUT) for providing the driving signal (U) that is coupled to the second main terminal, and a sensing resistor (R) coupled between the power supply terminal (V) and the first main terminal. The output driver (DRV) further has means for temporarily disabling the coupling between the control terminal and the control signal (V) during a peak voltage across the sensing resistor (R). The means may have a circuit that has a unidirectional current behavior, such as a diode (D), in series with the control terminal of the transistor (T).

Output driver equipped with a sensing resistor for measuring the current in the output driver

An electronic circuit comprising an output driver (DRV) for supplying a control signal (U), comprising a first power supply terminal (V); a second power supply terminal (V); a signal input terminal (IN) for receiving an input signal (U); a signal output terminal (OUT) for supplying the control signal (U); an output transistor (T) having a control terminal, and having a main current path coupled between the first power supply terminal (V) and the signal output terminal (OUT); and a control circuit (CNTRL) responsive to the input signal (U) which supplies a control signal (U) to the control terminal of the output transistor (T), which control circuit (CNTRL) comprises a buffer (BF) having an output which is coupled to the control terminal of the output transistor (T), and having a first power terminal which is coupled to the first power supply terminal (V). The control circuit also supplies a further control signal (U) to the control terminal of a further output transistor (T) which has a main current path coupled between the signal output terminal (OUT) and the second power supply terminal (V). The input signal (U) controls a switch S. In consequence, an input of the buffer is charged with a current value I by means of current source (J) or discharged with a current value I by means of current source (J) and current source (J). Thus a digital signal which is responsive to the input signal (U) is available at the input of the buffer (BF). The control circuit (CNTRL) further comprises a control field effect transistor (T) having a gate, a source connected to a second power terminal of the buffer (BF), and a drain connected to the second power supply terminal (V). A zener diode (Z) is connected between the second power supply terminal (V) and the gate of the control field effect transistor (T). A third current source (J) supplies current through the zener diode (Z). The potential at the gate of the control field effect transistor (T) is stabilized with respect to the potential at the first power supply terminal (V). Therefore also the potential (V) at the source of the control field effect transistor (T), and thus at the second power terminal of the buffer (BF), is more or less stabilized with respect to the potential at the first power supply terminal (V). The control field effect transistor (T) receives the current from the second power terminal of the buffer (BF) and transfers it to the second power supply terminal (V).

Output drive comprising an improved control circuit

A power supply arrangement having a DC/DC converter is presented that includes a control loop on the primary side of the isolation transformer within the DC/DC converter to control the voltage on the primary winding. The energy transfer across the isolation transformer is effected via control switches that alternately charge and discharge a capacitor through the primary winding. The control loop preferably adjusts the duty cycle of these control switches to control the voltage on the primary winding.

Power supply arrangement comprising a DC/DC converter with primary-side control loop

In a self-oscillating bridge circuit, the control of the low switch (6) is derived from the control of the high switch (7) by coupling the control circuitry (SC2) of the low switch to a terminal P in the control circuitry of the high switch by means of a diode (D1). The control of the low switch is improved by incorporating control circuitry (SC3) for rendering the low switch conducting for a short period after the high switch has become non-conducting.

Circuit arrangement

A reference voltage source comprises a first current branch (16, 36) and a second current branch (30, 34, 12). The voltage on a first terminal (6) in the first current branch (16, 26) is one junction voltage higher than the voltage on a second terminal (8) in the second current branch (30, 34, 12) owing to the presence of a transistor (80). The ratio between the current I.sub.1 through the first current branch (16, 36) and the current I.sub.2 through the second current branch (30, 34, 12) is thus determined by two non-linear characteristics having opposite temperature coefficients. A reference voltage (v.sub.z) with a small temperature coefficient and with a value which can be chosen freely can be generated by an appropriate choice of the resistance values for the resistors (58, 30, 16, 12) and by scaling the emitter areas of the transistors (34, 36, 70, 80).

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Nijmegen, Netherlands

Hendrikus Johannes Janssen