Siemens Aktiengesellschaft

Josef Einzinger

Roland Weber

Jenoe Tihanyi

Ludwig Leipold

Christine Fellinger

Jeno Tihanyi

Ludwid Leipold

A power MOSFET composed of a plurality of individual MOSFETs connected in parallel, wherein an additional sensing MOSFET monitors the current in the power MOSFET. The sensing MOSFET has a surface comparatively smaller than the power MOSFET and is connected in parallel with the power MOSFET with a resistor between the source of the power MOSFET and the source of the sensing MOSFET. The sensing MOSFET and resistor are integrated with an integrated circuit provided for the control of the power MOSFET.

Power MOSFET with current-monitoring

A semiconductor component with a power MOSFET and control circuit for controlling the power MOSFET. Both the power MOSFET and the control circuit have separate semiconductor bodies. The semiconductor body of the control circuit is arranged on one of the main surfaces of the semiconductor body of the power MOSFET. The control circuit is electrically insulated from the MOSFET by an insulating layer and mechanically coupled to the MOSFET by means of a bonding layer. The MOSFET is fastened to a cooling body which serves as a heat sink for the semiconductor component. The terminals of the control circuit and the MOSFET are attached to housing connections with leads.

Semiconductor component with power MOSFET and control circuit

A signal voltage (E) based upon a supply voltage must be converted to a signal voltage (A) with ground reference so as to enable further processing in a logic circuit. A simple level converter comprises a series connection of a MOSFET (T1) connected to the supply voltage; the MOSFET also comprises a resistor (T2). The source terminal of the MOSFET (T1) is located at the potential of the supply voltage. The voltage to be converted is applied between the gate terminal and the source terminal, and the converted voltage occurs at the resistor (T2). The two voltages are each limited by one Zener diode (D2, D1).

Integrable buffer circuit for voltage level conversion having clamping

The temperature of the power semiconductor component is sensed by a bipolar transistor. The bipolar transistor is in series with a depletion mode MOSFET whose gate and source electrodes are connected together. The drain electrode is also connected to a threshold element. Normally, the FET has low impedance, so that at the input of the threshold element source potential, e.g. ground potential, is present. With current rising as a function of temperature, the current through the FET is limited to a constant, essentially temperature-independent value, and the potential at the input of the threshold element rises steeply. This condition is detected as an overtemperature signal.

Overtemperature detection of power semiconductor components

The voltage peaks occuring upon disconnection of inductive loads are normally attenuated by a by-pass diode connected in parallel with the load. The driving countervoltage is thereby limited to the value of the forward voltage drop of the diode. For a power MOSFET with a source-side inductive load, the driving countervoltage is increased by placing a series connection of an additional MOSFET and a Zener diode between the gate of the power MOSFET and the connection of the load which is remote from the power MOSFET. The driving countervoltage at the source now becomes the Zener voltage plus the occuring gate-source voltage of the power MOSFET.

MOSFET switch with inductive load

When a power MOSFET operated as a source follower is driven by an electronic switch, an interruption of the connection between ground and the electronic switch may result in the output potential of the electronic switch to change so that the power MOSFET is partially switched on. This causes a considerable amount of power dissipation. Therefore, there is placed between the source and gate electrodes of the MOSFET a depletion MOSFET whose gate is connected to the terminal of the electronic switch intended for connection to ground. Thus, the power MOSFET remains non-conducting upon interruption of the connection between the electronic switch and ground.

Drive circuit for a power MOSFET with source-side load

A switching circuit includes two series-connected MOSFET (1, 6) complementing one another, which are interconnected at the drain terminal of each device. The gate terminal of the MOSFET that is grounded is connected to a control input terminal (E). This gate terminal is also connected to the source terminal of a depletion FET (7). The drain terminal of the depletion FET (7) is connected to the gate terminal of the second MOSFET (6) and, in turn, is connected via a resistor (8) to a voltage source (+U). The gate terminal of the depletion FET (7) is grounded. The load (5) is then connected to the drain side of the complementary MOSFET. When the switch is in a blocking condition, the cross current is thus prevented from flowing; and the FET connected to voltage can be completely activated.

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Unterschleissheim, Germany

Josef Einzinger