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High accuracy power-good signal generation

IP.com Disclosure Number: IPCOM000200922D
Publication Date: 2010-Oct-30
Document File: 2 page(s) / 54K

Publishing Venue

The IP.com Prior Art Database

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High accuracy power-good signal generation

Summary

Most power management circuits and systems require an accurate voltage reference to generate or control physical parameters. When the system is switched on, a delay is always necessary to get a fully stable reference. This delay is highly variable and various methods have been developed to inform that the startup phase is completed and that the system can start using the reference.

This paper described a simple method to detect that the reference has reached its steady state in order to enable a circuit or a system to start functioning.

Description of the invention

The invention is using simple voltage comparison to ensure that the reference voltage has not reached a wrong steady state. See Figure 1.

In the below example, the voltage reference must be above a given threshold and the power supply must be high enough to prevent saturation or clamp effects. These conditions do not significantly differ from prior art and are strongly linked with the voltage reference topology.

The novelty is that these conditions are used to enable a derivative calculation. The derivative is positive as long as the reference voltage keeps rising. When it becomes lower than a given threshold Delta, one can consider that the reference voltage has reached its steady state and the circuit is no more forced in reset state. The RS latch is not mandatory for the invention, but it is added to ensure that the circuit will not come back to Re...