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Low current consumption voltage regulator

IP.com Disclosure Number: IPCOM000035667D
Original Publication Date: 2005-Feb-25
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 58K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

The technical problem that has to be solved by this idea is to produce a regulated voltage from a wide range input voltage with very low quiescent current. In many applications like i.e. the generation of an internal supply in an integrated IC (Integrated Circuit) is not important that the regulator voltage has high performances but can be very important that the current consumption is low. Up to now, one way to solve this problem is shown in Fig. 1. This circuit consists in a voltage reference and a follower. The output voltage is Vref - Vgsq1. The Vref can be generated with a zener diode, with some diodes biased in forward direction or with a band gap. The disadvantages of this solution are that the output voltage has a poor precision and that a continuous current is always flowing. The quiescent current can be reduced by increasing the resistor R1 but this increases the area. An other way to generate a reference is to use a voltage regulator but also in this case a continuous quiescent current is unavoidable.

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Low current consumption voltage regulator

Idea: Marco Piselli, IT-Padova; Alberto Flore, IT-Padova

The technical problem that has to be solved by this idea is to produce a regulated voltage from a wide range input voltage with very low quiescent current. In many applications like i.e. the generation of an internal supply in an integrated IC (Integrated Circuit) is not important that the regulator voltage has high performances but can be very important that the current consumption is low.

Up to now, one way to solve this problem is shown in Fig. 1. This circuit consists in a voltage reference and a follower. The output voltage is Vref - Vgsq1.

The Vref can be generated with a zener diode, with some diodes biased in forward direction or with a band gap. The disadvantages of this solution are that the output voltage has a poor precision and that a continuous current is always flowing. The quiescent current can be reduced by increasing the resistor R1 but this increases the area.

An other way to generate a reference is to use a voltage regulator but also in this case a continuous quiescent current is unavoidable.

The circuit proposed solves the problem of the continuous quiescent current by sampling the voltage driving the output device. Accepting to worsening the dynamic performances in term of line and load regulation of the circuit in the hold condition, the regulation loop can be kept open and off. That will reduce the quiescent current exploiting the very low current required during the hold phase. In the circuit used the quiescent current is reduced from 50uA to 1.5uA.

The basic concept of the sampled voltage reference is shown in Fig. 2. The basic idea is to use two signals to power on the circuit and to store the reference in a capacitor.

The signals needed to drive this voltage reference are: An "Enable" signal that switch on the band gap, the regulator and the feedback resistor divider, a "Sample" signal that close the loop of the linear regulator. When "Enable" is low, the band gap and the feedback resistor divider are switched off and there is no continuous current flowing. When "Sample" is low, the voltage at the gate of the pass device is stored into a capacitor, so th...