A fully protected H-bridge for a d-c motor consists of two high side MOSFETs and a control and logic IC on a first conductive heat sink all within a first package and two discrete low side MOSFETs. The entire bridge is controlled by the IC. Shoot thru protection is provided for each leg, and a PMW soft start sequence is provided through the control of the low side MOSFETs, programed by an external, chargeable RC circuit. Input signals to the high side MOSFETs select the operation modes. Protective circuits are provided for short circuit current and over current conditions. Sleep mode and braking/non braking control is also provided.

H-bridge drive utilizing a pair of high and low side MOSFET's in a common insulation housing

A DC to DC converter which maintains high efficiency over broad current ranges in a current mode switching regulator circuit without changing operational mode. A low ripple voltage is maintained over the entire load range and good voltage regulation is maintained with high efficiency. This is possible because the switching frequency is adjusted in accordance with the load without changing operational states, thus making it unnecessary to define plural states of operation. The timing of turning on the switch(es) varies since the switch(es) is (are) turned on when two set (ready) signals both become ready. For fixed frequency switching applications, switching pulses from a fixed frequency oscillator as a first set signal are skipped when a second set signal is not ready. On the other hand, for a variable frequency switching scheme which is implemented by driving the switching with a one-shot having a constant OFF time, the switching pulse is created after both set signals become active. A low pass filter is also used to dynamically adjust the minimum peak inductor current and to minimize ripple voltage for low load conditions so that a smaller output capacitor may be used.

DC to DC converter with high efficiency for light loads

An improved distribution automation remote terminal unit which directly connects to a distribution feeder. The distribution automation remote terminal unit of the present invention is directly connected to voltage and current sensors on the feeder to sense the presence of signals on the distribution feeder. The remote terminal unit includes the first transformer interconnected to the potential sensors to produce a potential signal of reduced peak-to-peak voltage corresponding in phase to the AC potential waveform on the distribution feeder. A second transformer is directly coupled to the current sensor for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on the distribution feeder. The reduced peak-to-peak voltage signals are delivered into a multiplexer and are sampled a predetermined number of times. The sampled analog voltage is then digitized by a digital to analog converter and delivered into a digital signal processor. Waveform parameters are determined. A microcontroller then accesses the waveform parameters to determine information such as the operation of upstream and downstream devices on the distribution feeder. This information is selectively transmitted to a remote master station over a communications link.

Distribution automation smart remote terminal unit

A cooling system includes a cooling fan, a fan input-output module for transmitting a control signal to the fan for controlling the rotational speed of the fan, and a chipset interface for generating the fan control signal based on a change in a vital temperature of the computer system. Further provided is a controller for receiving the vital temperature and forwarding the vital temperature to the chipset interface, and a temperature transducer for generating the vital temperature and outputting the vital temperature to the controller. The chipset interface monitors a rotational speed of the cooling fan, and monitors a vital temperature of the computer system. The chipset interface then sets the fan power based on a change in the vital temperature. When the vital temperature decreases, the fan power is reduced to slow the fan, and when the vital temperature increases, the fan power is increased to speed the fan.

Computer cooling system

A plurality of power supplies are connected in parallel, each power supply isolated from the others using a non-linear isolation element such as a barrier diode. Feedback is furnished around the non-linear isolation element such that the voltage drop of the isolation element is reduced to be within the regulation range desired. The non-linear characteristic of the isolation element combined with feedback produces an output impedance which is low for high currents, and exponentially higher for low output currents for current sharing versus output offset voltage improvement.

Current sharing power supplies with redundant operation

A matched pair of npn transistor configured as emitter followers provide high impedance isolation for input error voltage busses in the current share circuitry used with parallel connected current programmed dc to dc converters. The matched emitter followers offer the bus isolation of buffer amplifiers but do not add the detrimental offset voltage to the input error signals. Trimmable current sinks are connected to the emitters of the transistors to guarantee equal VBE drops. Slight intentional unbalancing can be introduced using the current sources to improve stability. The current share circuitry equalizes main FET switching currents not load currents reducing FET stresses. A programmable differential amplifier is provided which can accommodate different regulator output voltages. Diagnostic circuitry monitors share circuitry operation.

Current share circuit for DC to DC converters

A temperature compensated control circuit includes a load transistor which passes the load current and has an on-resistance which varies with temperature. To provide temperature compensation, first and second pilot transistors are integrated with the load transistor such that as the load transistor heats-up due to the load current passing through the on-resistance of the load transistor, the first and second pilot transistors heat-up due to heat conduction from the load transistor. Each of the pilot transistors has an on-resistance which varies proportionally or similarly to the on-resistance of the load transistor. A first current source supplies a first level of current to the on-resistance of the first pilot transistor to develop a first reference voltage, and a second current source supplies a second level of current to the on-resistance of the second pilot transistor to develop a second reference voltage. The range between the first and second reference voltages corresponds to an acceptable range of load current. A voltage corresponding to the load current is sensed across the load transistor, and the control circuit controls the load current to maintain the sensed voltage within the range.

Temperature compensated circuit for controlling load current

A power supply system, which supplies a number of different A.C. and D.C. voltage levels to a plurality of loads, is monitored at a number of points for undervoltage, overvoltage and/or overcurrent fault conditions. A diagnostics logic circuit, which is formed from relatively inexpensive, readily available logic units, generates a BCD code signal indicating a fault in response to the occurrence of a fault condition at one of the monitored points. The system responds to this BCD fault indicating code signal by, on the one hand, protecting the power system by actuating a main relay to open the A.C. power line to the system and generating a shutdown signal applied to a pulse width modulator of a converter in the system and, on the other hand, by driving a seven-segment display which displays a numeral to indicate the location of the fault condition. In order to avoid false undervoltage fault signals while the system voltages are coming up after the system is turned on, a delay circuit is used to mask the BCD code generating portion of the diagnostics logic until the system voltages reach normal operating levels.

Power control and fault isolation indicator

A load transistor is integrated into a region of a semiconductor layer. The load transistor has an on-resistance which passes the load current. One or more drain pilot transistors are also integrated into the same region of the semiconductor layer such that the load transistor substantially surrounds the pilot transistor(s). Consequently, as the load transistor heats-up due to the load current, the heat from the load transistor conducts to the pilot transistor(s) and heats the pilot transistor(s) to substantially the same temperature as the load transistor. If more than one drain pilot transistor are provided, then they are located adjacent to each other to ensure that all the pilot transistors exhibit substantially the same temperature as each other. The pilot transistor(s) are scaled models of the load transistor such that an on-resistance of each of the pilot transistors varies proportionally to the on-resistance of the load transistor with temperature. Current sources supply fixed currents to the on-resistances of the respective pilot transistors. Consequently, voltage(s) developed across the pilot transistor(s) are accurate references with which to set a drive voltage for the load current or an overcurrent or undercurrent detector, which reference voltages are temperature compensated.

Temperature monitoring pilot transistor

A temperature compensated overcurrent and/or undercurrent detector monitors current through a solenoid or other load and signals when the load current exceeds an upper limit or falls below a lower limit. Such a signal may indicate a failure of another circuit which supplies the load current via a load transistor. This other circuit which supplies the load current is temperature compensated, and likewise the detector is temperature compensated so it can be set to signal an overcurrent or undercurrent condition when the load current varies a small amount from a predetermined range. The load transistor has an on-resistance which passes the load current and varies with temperature. The temperature compensation for the detector is provided in part by two pilot transistors which are integrated with the load transistor such that as the load transistor heats-up due to the load current passing through the on-resistance, the pilot transistors heat-up due to heat conduction from the load transistor. Each pilot transistor also has an on-resistance which varies proportionally or similarly to the on-resistance of the load transistor. A current source is coupled to the on-resistance of each pilot transistor to generate reference voltages above and below the acceptable range of voltages sensed by the sensor representing an acceptable range of load currents.

Donald J. Ashley

Papers

Current share circuit for DC to DC converters

Temperature compensated circuit for controlling load current

Power control and fault isolation indicator

Temperature monitoring pilot transistor

Temperature compensated overcurrent and undercurrent detector