ADSP-21368 SHARC Processor Hardware Reference 14-27
System Design
Reset Generators
It is important that a processor (or programmable device) have a reliable
active
RESET that is released once the power supplies and internal clock cir-
cuits have stabilized. The RESET signal should not only offer a suitable
delay, but it should also have a clean monotonic edge. Analog Devices has
a range of microprocessor supervisory ICs with different features. Features
include one or more of the following:
• Power-up reset
• Optional manual reset input
• Power low monitor
• Backup battery switching
The part number series for reset and supervisory circuits from Analog
Devices are as follows:
• ADM69x
• ADM70x
• ADM80x
• ADM1232
• ADM181x
• ADM869x
A simple power-up reset circuit is shown in Figure 14-6 using the
ADM809-RART reset generator. The ADM809 provides an active low
RESET signal whenever the supply voltage is below 2.63 V. At power-up, a
240 μs active reset delay is generated to give the power supplies and oscil-
lators time to stabilize.
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