Abstract: A protective structure having a plurality of protection regions extending along closed lines arranged inside each other. Each intermediate protective region is tangent to two different adjacent protective regions, at different areas, so as to form a connection in series with the adjacent protective regions. The protective structure can be of resistive material, such as to form a series of resistors, or it can include doped portions alternately of P- and N-type, such as to form a plurality of anti-series arranged diodes. The structure can be made of polycrystalline silicon extending on the substrate surface, or can be integrated (implanted or diffused) inside the substrate.

Abstract: A circuit to control the supply of a reactive load, for supplying variable quantities of energy to the load in a predetermined manner is included in a system. The system also includes reactive components which are connected to the load by way of a controllable electronic switch and which form a resonant circuit with the load when the electronic switch is closed. Further, the system includes a circuit for activating the electronic switch, and a control unit which coordinates the operation of the controlled supply circuit and of the activation circuit in accordance with a predetermined program. The system enables the load to be driven with a particularly low power dissipated.

Abstract: An H-bridge for applying a current to a coil of a write head assembly for writing data to a magnetic media includes two pair of two switchable transistors. Each pair of transistors is connected between a supply voltage and a reference potential and is adapted to be connected to the coil between the transistors of each pair for turning the transistors turned on and off in a sequence to control the direction of current flow in the coil. The upper transistors of each pair serves a switching transistor, and the lower transistors provide a mirrored referenced current to the coil. A pair of capacitors are connected to a control element of a respective associated one of the lower transistors, and switching circuitry is connected to the capacitors to selectively connect each of the capacitors to inject current into the control element of the respective associated lower transistor when the respective associated lower transistor is turned on.

Abstract: An H-bridge circuit having a boost capacitor coupled to the gate of the low-side driver. A driver, in the form of a switching transistor is connected between the load and ground, thus providing a low-side driver. A capacitor is coupled to the gate of the low-side driver to provide a boosted voltage for rapid turn on of the gate. The size of the capacitor selected to be similar to the size of the capacitance associated with the low-side driver transistor.

Abstract: A method and apparatus, for applying a current to a coil of a write head assembly of a disk drive, or the like, to cause the flux within the coil to rapidly reverse, has an H-bridge having two pair of two switchable transistors. Each pair of the transistors is connected between a supply voltage and a reference potential, and is adapted to be connected to the coil between the two transistors of each pair. The two transistors of the first pair may be connected to receive a control signal to turn on complementary transistors of the first and second pair of transistors to selectively control current flow in the coil in first or second directions. A reference current source supplies a reference current, and one of the transistors in each of the first and second pairs of transistors is connected when turned on to mirror the reference current to control the currents in the coil.

Abstract: A control system provides an improvement in the stability and immunity to noise characteristics without degrading performance of the circuit by including a multiplier circuit that is purposely made nonlinear. A parameter K of the multiplier circuit is not a fixed value, but varies as a function of the error signal amplitude that is applied to one of the two inputs of the multiplier circuit. Advantageously, the parameter K of the multiplier circuit decreases when the amplitude of the error signal input thereto decreases.

Abstract: A circuit for detecting voltage variations in relation to a set value, for devices, such as a power supply circuit, comprising an error amplifier fed back by a compensating capacitor which, under steady state operating conditions, is not supplied with current, and, in the presence of transient output voltage (V.sub.o) of the device, is supplied with current (DI) proportional to the variation in voltage, the circuit comprising a current sensor connected to the compensating capacitor for detecting the current (DI) through the same; and the output signal of the sensor preferably being supplied to a circuit for limiting the variation in output voltage which, in the event the voltage variation exceeds a given threshold value (V.sub.R1), activates a control stage connected to the output of the device.

Abstract: A power supply in which control of the switch-on instant of a power device of a boost-circuit (operating in a discontinuous mode) is implemented by monitoring the current which actually flows through the "fly-back" inductance. The current is monitored on a sensing resistance, and, by the use of a comparator, a signal is produced for enabling/disabling the transfer to an input of a PWM driving circuit of a switch-on signal produced by a null detector. This configuration provide good noise immunity, which is particularly useful in power-factor-correction applications, and reduced power dissipation.

Abstract: A level shifter, particularly suited for driving power stages for supplying power to integrated circuits, includes a DMOS transistor (40) which is driven by a digital signal source (42) and has a load resistor (44) as its drain load. A shifted output signal develops at the ends of said load resistor. The drain (V1) of the DMOS transistor is connected to the input of an inverter (46), while a Zener diode (54) and a second transistor (52) are connected in parallel with the load resistor (44), the gate of the second transistor (52) being driven by the output of the inverter (46). The output of the inverter (46) can be connected to the input of a drive stage (48), the output of which drives a power stage (50) for supplying power to an integrated circuit.

Abstract: A driving circuit for driving a floating circuit (28) responsive to a digital signal (IN) includes two DMOS transistors (10, 12) which are driven in opposite phase on their respective gates starting from the digital signal. The two DMOS transistors are biased by a current source which is formed by a current mirror (16, 18), which mirrors a reference current (I.sub.BIAS), and by an auxiliary circuit (34-44) for injecting an additional current pulse during switching. Two MOS transistors (20, 22) serve as the respective loads for the two DMOS transistors. The MOS transistors can be P-channel transistors, in which event the gate of each MOS transistor (20, 22) can be connected to the drain of the other MOS transistor. Two Zener diodes (24, 26) can be employed to limit the voltage between the gate and source of the respective MOS transistor. The driving output of the floating circuit (28) can be the drain of one of the DMOS transistors.