AT83EC5123 ATMEL Corporation, AT83EC5123 Datasheet - Page 137

• Manufacturer Part Number: AT83EC5123
• Description: (AT8xx512x) Smart Card Reader ICs
• Manufacturer: ATMEL Corporation

Power Monitor
Overview
Description
Figure 83. Power Monitor Block Diagram
Power Monitor Diagram
4202B–SCR–07/03
Power-Supply
External
VCC
The Power Monitor function supervises the evolutions of the voltages feeding the micro-
controller, and if needed, suspends its activity when the detected value is out of
specification.
It guarantees to start up properly when AT8xC5122 is powered up and prevents code
execution errors when the regulated power supply becomes lower than the functional
threshold.
This section describes the functions of the Power Monitor.
In order to startup and to maintain properly the microcontroller operation, VCC has to be
stabilized in the VCC operating range and the oscillator has to be stabilised with a nom-
inal amplitude compatible with logic threshold.
This control is carried out during three phases which are the power-up, normal operation
and stop. So it is in accordance with the following requirements:
•
•
The target of the Power monitor is to survey the power-supply in order to detect any volt-
age drops which are not in the target specification. This Power Monitor checks two kind
of situations which occur:
•
•
Figure 84 shows some configurations which can be met by the Power monitor.
Power up
Detector
it guarantees an operationnal Reset when the microcontroller is powered
and a protection if the power supply goes out from the functional range of the
microcontroller.
during the power-up condition, when VCC is reaching the product specification,
during a steady-state condition, when VCC is stable but disturbed by any
undesirable voltage drops.
DC to DC
3.3V Regulator
Power Fail
Detector
DVCC
CVCC
Internal RESET
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