ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 51

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

11.7
11.7.1
11.8
11.8.1
11.8.2
9223B–AVR–09/11
Watchdog Timer
Internal Voltage Reference
Voltage Reference Enable Signals and Start-up Time
Features
Overview
The Atmel
ence is used for Brown-out Detection, and it can be used as an input to the Analog
Comparator or the ADC.
The voltage reference has a start-up time that may influence the way it should be used. The
start-up time is given in
reference is not always turned on. The reference is on during the following situations:
Thus, when the BOD is not enabled, after setting the ACBG bit or enabling the ADC, the user
must always allow the reference to start up before the output from the Analog Comparator or
ADC is used. To reduce power consumption in Power-down mode, the user can avoid the
three conditions above to ensure that the reference is turned off before entering Power-down
mode.
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The Atmel ATmega48PA/88PA/168PA has an Enhanced Watchdog Timer (WDT). The WDT
is a timer counting cycles of a separate on-chip 128kHz oscillator. The WDT gives an interrupt
or a system reset when the counter reaches a given time-out value. In normal operation mode,
it is required that the system uses the WDR - Watchdog Timer Reset - instruction to restart the
counter before the time-out value is reached. If the system doesn't restart the counter, an
interrupt or system reset will be issued.
1. When the BOD is enabled (by programming the BODLEVEL [2:0] Fuses).
2. When the bandgap reference is connected to the Analog Comparator (by setting the
3. When the ADC is enabled.
Clocked from separate On-chip Oscillator
3 Operating modes
Selectable Time-out period from 16ms to 8s
Possible Hardware fuse Watchdog always on (WDTON) for fail-safe mode
– Interrupt
– System Reset
– Interrupt and System Reset
Atmel ATmega48PA/88PA/168PA [Preliminary]
ACBG bit in ACSR).
®
ATmega48PA/88PA/168PA features an internal bandgap reference. This refer-
“System and Reset Characteristics” on page
318. To save power, the
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