AT43USB325E-AU Atmel, AT43USB325E-AU Datasheet - Page 25

• Manufacturer Part Number: AT43USB325E-AU
• Description: IC USB KEYBOARD CTRLR 64LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB325E-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: SRAM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: SPI, 3-Wire Serial
• Number Of I /o: 42
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.7
4.8
3355C–USB–4/05
External Reset
Watchdog Timer Reset
An external reset is generated by a low-level on the RESET pin. Reset pulses longer than
200 ns will generate a reset. Shorter pulses are not guaranteed to generate a reset. When the
applied signal reaches the Reset Threshold Voltage - V
starts the MCU after the Time-out period t
Figure 4-4.
When the watchdog times out, it will generate a short reset pulse of 1 XTAL cycle duration. On
the falling edge of this pulse, the delay timer starts counting the Time-out period t
Figure 4-5.
INTERNAL
TIME-OUT
TIME-OUT
RESET
RESET
RESET
WDT
VCC
TIME-OUT
INTERNAL
RESET
RESET
VCC
External Reset During Operation
Watchdog Reset During Operation
V
RST
1 XTAL Cycle
t
TOUT
t
TOUT
TOUT
has expired.
RST
on its positive edge, the delay timer
AT43USB325
TOUT
.
25