One of the important points in critical projects involving microcontrollers or digital circuits is the stability of the supply voltage. Variations in the supply voltage can affect the operation of the circuit and consequently the safety of the application, depending on the case. See in this article how Diodes Incorporated's APX803L voltage detectors work and are used.
Diodes Incorporated's micro-power voltage detectors (available from Mouser Electronics at http://www.mouser.com/new/diodes-inc/diodes-inc-apx803l-detectors/) and whose datasheet can be downloaded at: http://www.mouser.com/pdfdocs/APX803Lds.pdf consist of extremely low voltage (1.0 uA typical) voltage detectors whose main application is to supervise the supply voltage of microprocessors and digital systems.
The available types of the APX803L series can detect voltage levels in the range of 1.2 to 5.0 V in steps of 0.1 V and with an accuracy of +/- 1.5%
In figure 1 we have the pinout of these components that can be obtained in three types of enclosures.
Applications include computers, controllers, smart instruments, portable and battery powered equipment, etc.
The purpose of these circuits is to send a reset signal when the monitored voltage drops below a certain value. The reset signal remains as long as the monitored voltage is below the set level.
The output configuration is of the open drain type and the various components available in the series have delays that can be chosen between 0 ms and 450 ms.
In figure 2 we have a typical circuit of application.
The block diagram of is shown in figure 3.
In figure 4 we have a timing diagram showing the various signal levels as a function of a variation of the input voltage being monitored.
