Embodiments of the present invention provide methods and circuitry for protecting a circuit during hot-swap events. Hot swap protection circuitry includes as overcurrent detection circuit which decouples power from a load. Circuitry is provided to detect ground-fault conditions. Noise detection circuitry is provided to reduce noise in the power that is delivered to the load.

Hot-swap protection circuit

A band-gap filter circuit is disclosed for use in a voltage regulator. A capacitor charger (or “cap charger”) circuit quickly charges a filter capacitor when power is applied to the voltage regulator circuit. At start-up, the cap charger begins charging the filter capacitor. Once an output node equals or nearly equals the voltage at the input node, the cap charger shuts off. The circuit provides a very fast turn-on time, reaching 95% of its steady state value within 200 microseconds, thus overcoming the long turn-on times associated with other designs. The present invention may be utilized in power sensitive applications, such as cellular telephones, that wish to shut off the voltage regulator in order to conserve power.

Low noise high PSRR band-gap with fast turn-on time

A reference-producing integrated circuit that is able to rapidly transition from an enable mode to a disable mode is disclosed. The reference-producing integrated circuit can, for example, be a voltage reference integrated circuit or a voltage regulator. In one implementation, the voltage reference integrated circuit or the voltage regulator can provide a low dropout voltage output. The reference-producing integrated circuit is particularly useful for reducing power consumption by electrical circuitry (e.g., portable computing devices) being power managed at least in part through control of the voltage reference supplied to the electrical circuitry.

Voltage reference circuit with fast disable

A voltage monitor having a bandgap reference circuit driven by a voltage to be monitored. The bandgap reference circuit produces a voltage and a second voltage that each vary with the voltage to be monitored. The magnitudes of these voltages are compared by an open loop comparator to provide a high speed output state. The output of the voltage monitor can be used to monitor a supply voltage and produce a reset signal to a processor if the supply voltage falls to a magnitude below a specified threshold.

Supply voltage monitor using bandgap device without feedback

An apparatus and a method to control an output signal from a DAC-driven amplifier-based driver are disclosed. The apparatus includes an amplifier and a driver. The amplifier has a negative input terminal, a positive input terminal, and a first output terminal. The driver has an input terminal and a second output terminal, the input terminal coupled to the first output terminal of the amplifier and the second output terminal coupled to the positive input terminal of the amplifier to provide a positive feedback to the amplifier. In another embodiment, the apparatus includes a first driver to drive an output signal, the first driver having a first input terminal and a first output terminal, a second driver to generate a feedback, the second driver having a second input terminal and a second output terminal, and an amplifier having a third input terminal to receive an input signal, a fourth input terminal, and a third output terminal, the third output terminal coupled to the first input terminal of the first driver and the second input terminal of the second driver, the fourth input terminal coupled to the second output terminal of the second driver.

Output signal control from a DAC-driven amplifier-based driver

The rise time of a voltage Vo presented to a load, based on an input voltage Vi provided via an RC filter coupled to the load for removing higher frequency noise on Vo, is substantially reduced by providing a sensor circuit with differential inputs Vi, Vo. The sensor circuit drives a charger circuit coupled to a DC potential and the load so that rapid charging of C to Vo does not depend on R. As Vo approaches Vi, the sensor circuit deactivates the charger circuit to stop further charging and a latch coupled to the sensor circuit shuts off the sensor circuit to reduce power consumption while (Vo˜Vi)>0. A current mirror buffer is desirably included between the sensor output and the latch for level shifting.

Fast start-up circuit

PROBLEM TO BE SOLVED: To provide an electronic device of simple constitution and low power consumption provided with high-speed start-up characteristics. SOLUTION: Based on an input voltage Vi provided through RC filters 6 and 12 connected to a load 4 for removing high frequency noise, the rising time of a voltage Vo provided in the load 4 is reduced by a detection circuit 22 provided with differential input Vi=Vo. The detection circuit drives a charging circuit 24 connected to the load and a DC potential 62 and prevents quick charging to Vo of C from depending on R. Corresponding to the approach of Vo to Vi, the detection circuit 22 makes the charging circuit 24 inoperative and stops further charging, a latch shuts off the detection circuit and the power consumption during (Vo:=Vi)>0 is reduced.

Afek Yachin

Papers

Fast start-up circuit

Electronic device provided with high-speed start-up characteristic