89C5121-SK1 Atmel, 89C5121-SK1 Datasheet - Page 14

• Manufacturer Part Number: 89C5121-SK1
• Description: KIT SMART CARD FOR AT89C5121
• Manufacturer: Atmel
• Type: Smart Cardr

Specifications of 89C5121-SK1

• Contents: Board
• For Use With/related Products: AT89C5121
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: T89C5121-SK1; T89C5121-SK1

PowerMonitor
Description
Figure 8. PowerMonitor Block Diagram
PowerMonitor Diagram
14
A/T8xC5121
Power Supply
External
V
DD
The PowerMonitor function supervises the evolution of the voltages feeding the micro-
controller, and if needed, suspends its activity when the detected value is out of
specification.
It is guaranteed to start up properly when T8xC5121 is powered up and prevents code
execution errors when the power supply becomes lower than the functional threshold.
This section describes the functions of the PowerMonitor.
In order to start up and to properly maintain the microcontroller operation, V
stabilized in the V
nal amplitude compatible with logic threshold.
This control is carried out during three phases which are the power-up, normal operation
and stop. It complies with the following requirements:
•
•
The target of the PowerMonitor is to survey the power supply in order to detect any volt-
age drops which are not in the target specification. This PowerMonitor block checks two
kind of situations that occur:
•
•
Figure 9 shows some configurations that can be met by the PowerMonitor.
It guarantees an operational 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 V
During a steady-state condition, when V
undesirable voltage drops.
Power-up
Detector
DD
DC to DC
3V Regulator
operating range and the oscillator has to be stabilised with a nomi-
Power-fail
Detector
DV
CV
CC
CC
DD
DD
is reaching the product specification
is stable but disturbed by any
Internal RESET
4164G–SCR–07/06
DD
has to be