AT90USB1287-16AUR Atmel, AT90USB1287-16AUR Datasheet - Page 62

• Manufacturer Part Number: AT90USB1287-16AUR
• Description: IC MCU AVR 128K ISP USB TQFP64
• Manufacturer: Atmel
• Series: AVR® 90USBr

Specifications of AT90USB1287-16AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART, USB, USB OTG
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 48
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK525 - KIT STARTER FOR AT90USBAT90USBKEY2 - KIT DEMO FOR AT90USB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.7
8.7.1
62
Internal Voltage Reference
AT90USB64/128
Voltage Reference Enable Signals and Start-up Time
• Bit 2 – BORF: Brown-out Reset Flag
This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 1 – EXTRF: External Reset Flag
This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by writing a
logic zero to the flag.
• Bit 0 – PORF: Power-on Reset Flag
This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to the flag.
To make use of the Reset Flags to identify a reset condition, the user should read and then
Reset the MCUSR as early as possible in the program. If the register is cleared before another
reset occurs, the source of the reset can be found by examining the Reset Flags.
AT90USB64/128 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 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 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.
Table 8-4.
Symbol
1. When the BOD is enabled (by programming the BODLEVEL [2..0] Fuse).
2. When the bandgap reference is connected to the Analog Comparator (by setting the
3. When the ADC is enabled.
V
t
I
BG
BG
BG
ACBG bit in ACSR).
Parameter
Bandgap reference voltage
Bandgap reference start-up time
Bandgap reference current
consumption
Internal Voltage Reference Characteristics
Table
8-4. To save power, the reference is not always turned on. The
Condition
Min
1.0
Typ
1.1
40
10
Max
1.2
70
Units
7593K–AVR–11/09
µA
µs
V