ATMEGA8535L-8AC Atmel, ATMEGA8535L-8AC Datasheet - Page 41

• Manufacturer Part Number: ATMEGA8535L-8AC
• Description: IC AVR MCU 8K LV 8MHZ COM 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8535L-8AC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Internal Voltage
Reference
Voltage Reference Enable
Signals and Start-up Time
Watchdog Timer
2502K–AVR–10/06
ATmega8535 features an internal bandgap reference. This reference is used for Brown-
out Detection, and it can be used as an input to the Analog Comparator or the ADC. The
2.56V reference to the ADC is generated from the internal bandgap reference.
The voltage reference has a start-up time that may influence the way it should be used.
The start-up time is given in Table 16. To save power, the reference is not always turned
on. The reference is on during the following situations:
1. When the BOD is enabled (by programming the BODEN Fuse).
2. When the bandgap reference is connected to the Analog Comparator (by setting
3. When the ADC is enabled.
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 Com-
parator 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.
Table 16. Internal Voltage Reference Characteristics
Note:
The Watchdog Timer is clocked from a separate On-chip Oscillator which runs at
1 MHz. This is the typical value at V
at other V
interval can be adjusted as shown in Table 18 on page 43. The WDR – Watchdog Reset
– instruction resets the Watchdog Timer. The Watchdog Timer is also reset when it is
disabled and when a Chip Reset occurs. Eight different clock cycle periods can be
selected to determine the reset period. If the reset period expires without another
Watchdog Reset, the ATmega8535 resets and executes from the Reset Vector. For tim-
ing details on the Watchdog Reset, refer to page 40.
To prevent unintentional disabling of the Watchdog or unintentional change of Time-out
period, three different safety levels are selected by the Fuses S8535C and WDTON as
shown in Table 17. Safety level 0 corresponds to the setting in AT90S8535. There is no
restriction on enabling the WDT in any of the safety levels.
Symbol
V
the ACBG bit in ACSR).
t
I
BG
BG
BG
1. Values are guidelines only.
CC
Parameter
Bandgap reference voltage
Bandgap reference start-up time
Bandgap reference current consumption
levels. By controlling the Watchdog Timer prescaler, the Watchdog Reset
CC
= 5V. See characterization data for typical values
(1)
ATmega8535(L)
1.15
Min
1.23
Typ
40
10
Max
1.35
70
Units
µA
µs
V
41