ATA6020N ATMEL Corporation, ATA6020N Datasheet - Page 12

• Manufacturer Part Number: ATA6020N
• Description: Low-current Microcontroller For Watchdog Function
• Manufacturer: ATMEL Corporation

4.2.2
4.2.3
12
ATA6020N
Watchdog Reset
External Clock Supervisor
A power-on reset pulse is generated by a V
A brown-out reset pulse is generated when V
values for the brown-out voltage threshold are programmable via the BOT-bit in the SC-register.
When the controller runs in the upper supply voltage range with a high system clock frequency,
the high threshold must be used. When it runs with a lower system clock frequency, the low
threshold and a wider supply voltage range may be chosen. For further details, see the electrical
specification and the SC-register description for BOT programming.
Figure 4-8.
The watchdog's function can be enabled at the WDC-register and triggers a reset with every
watchdog counter overflow. To suppress the watchdog reset, the watchdog counter must be
regularly reset by reading the watchdog register address (CWD). The CPU reacts in exactly the
same manner as a reset stimulus from any of the above sources.
The external input clock supervisor function can be enabled if the external input clock is selected
within the CM- and SC-registers of the clock module. The CPU reacts in exactly the same man-
ner as a reset stimulus from any of the above sources.
Reset
Reset
CPU
CPU
4.0 V
3.0 V
V
DD
BOT = 1, low brown-out voltage threshold. (3.0V is the reset value).
BOT = 0, high brown-out voltage threshold (4.0V).
Brown-out Detection
BOT = 0
BOT = 1
t
d
= 1.5 ms (typically)
t
d
t
d
DD
DD
rise across the default BOT voltage level (3.0 V).
falls below the brown-out voltage threshold. Two
t
d
t
4708D–4BMCU–09/05