摘要:
A method of controlling the charging of a bootstrap capacitance incorporated into a switching regulator of a power transistor includes the steps of comparing, at each switching cycle, the voltage value at the bootstrap capacitance and a predetermined threshold voltage, to change the mode of operation of the regulator following said comparison. More particularly, the control on the transistor is taken off the regulator when the voltage at the bootstrap capacitance is lower than the threshold voltage, while the transistor is forced into the "on" state through a full cycle. In this way, the minimum current to operate the regulator can be minimised.
摘要:
A synchronization circuit for electronic devices and components, being of the type which includes an internal synchronization signal generator and an input/output terminal whereat an external synchronization signal can be received. The synchronization circuit further includes a comparator for receiving both synchronization signals and having a control output for supplying a terminal with the signal corresponding to the master/slave mode of operation of the synchronization circuit. A method of generating and supplying a synchronization signal to a plurality of electronic devices being operated as slave devices to a synchronization circuit acting as the master device is also provided.
摘要:
A driver circuit is for turning on at least one power MOS transistor having a diode connected thereto. The driver circuit preferably includes a smart driver circuit portion for increasing a drive current to the power MOS transistor responsive to turning on of the diode. The smart driver circuit may include a comparator having one input connected to the diode and a second input connected to a threshold signal indicative of the turning on of the diode. The smart driver circuit may also comprise: a first current source for supplying a first drive current; a second current source for supplying a second drive current; and a switch for connecting the second current source to the power MOS transistor responsive to the comparator. The smart driver circuit may further include a turn off circuit for turning off the increased drive current a predetermined time after turning on same, such as before turning off the first current. In addition, the second current source may supply a second drive current at least one order of magnitude larger that the first drive current. Of course, the driver circuit may be implemented with bipolar and MOS transistors Buck, boost, and buck-boost regulators may be implemented.
摘要:
A method and a circuit for minimizing glitches in phase-locked loops is presented. The circuit includes an input terminal connected to an input of a phase detector; a series of a charge pump generator, a filter and a voltage controlled oscillator connected downstream of the phase detector; and a frequency divider feedback connected between an output of the voltage controlled oscillator and a second input of the phase detector. The circuit provides for the inclusion of a compensation circuit connected between the charge pump generator and the filter to absorb an amount of the charge passed therethrough. This compensation circuit includes a storage element connected in series to two switches. The first switch is coupled to and controlled by an output of the charge pump and the second switch is coupled to and controlled by an output of a phase detector.
摘要:
An electronic device smoothes a charge current peak in RLC output stages of switching step-up regulators, which stages include an input terminal and an output terminal with an inductance and a parasitic resistance in series therebetween, the latter corresponding to the series parasitic resistance of the inductance, and a capacitor connected between the output terminal and a ground. The device comprises a parallel of a resistor and a controlled switch connected between the inductance and the output terminal of the stage upstream of the capacitor. Advantageously, the switch would only be open during the charge transient of the capacitor.
摘要:
A translator circuit for a drive circuit of a power transistor connected to an electric load. The translator circuit includes a first current generator placed between a supply voltage reference and an input terminal of the drive circuit, a controlled switch placed between the input terminal and a ground reference, and a second current generator interposed between the controlled switch and the ground reference. The translator circuit further includes a circuit leg in the form of a current mirror connected in parallel with the second current generator. The translator circuit avoids phenomena of false switching.
摘要:
A low noise adaptive bias circuit is provided for a low noise bipolar junction input transistor having an emitter degeneration inductance, of an integrated high frequency functional circuit driven by the collector current of the input transistor. The bias circuit includes a shunt line connecting the base node of the input transistor to a first supply node of opposite sign of that of a second supply node to which is coupled, through the degeneration inductance, to the emitter of the input transistor. The shunt line includes a bias current generator dependent, in an inversely proportional manner, on the current gain of the input transistor, and a resistance dependent, in a directly proportional manner, on the current gain of the input transistor.
摘要:
Switching and propagation delays in generating a PWM control signal by a circuit that generally includes an error amplifier, a sawtooth oscillator and a comparator for comparing the error signal with the sawtooth signal, is compensated by generating a second sawtooth signal synchronous with the master sawtooth signal but having a reduced discharge time and by applying the second synchronous sawtooth signal to the respective input of the PWM comparator.