U5021M-NFP Atmel, U5021M-NFP Datasheet - Page 4

• Manufacturer Part Number: U5021M-NFP
• Description: IC TIMER WATCHDOG DIGITAL 8-SOIC
• Manufacturer: Atmel
• Type: Watchdog Circuitr

Specifications of U5021M-NFP

• Number Of Voltages Monitored: 1
• Output: Open Drain or Open Collector
• Reset: Active High
• Reset Timeout: Adjustable/Selectable
• Voltage - Threshold: 4.2V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Figure 3. Period t versus R
Figure 4. Power-on Reset and Switch-over Mode
Supply Voltage
Monitoring, Pin 5
Switch-over Mode Time,
Pin 3
4
t (µs)
U5021M
Mode
Reset Out
VDD
1000.00
100.00
10.00
1.00
1
1
, at C
1
During ramp-up of the supply voltage and in the case of supply-voltage drops the inte-
grated power-on reset (POR) circuitry sets the internal logic to a defined basic status
and generates a reset pulse at the reset output, pin 5. A hysteresis in the POR threshold
prevents the circuit from oscillating. During ramp-up of the supply voltage, the reset out-
put stays active for a specified period of time (t
its defined reset status (see Figure 4). Pin 5 has an open-drain output.
The switch-over mode time enables the synchronous operation of microcontroller and
watchdog. When the power-on reset time has elapsed, the watchdog has to be switched
to monitoring mode by the microcontroller by a “low” signal transmitted to the mode pin
(pin 3) within the time-out period, t
4), the watchdog generates a reset pulse, t
watchdog are synchronized with the switch-over mode time, t
is generated.
= 500 pF
t
0
10
R
1
(k )
t
1
1
. If the low signal does not occur within t
C
1
100
= 500 pF
6
, and t
0
) in order to bring the microcontroller into
1
starts again. Microcontroller and
t
6
5.5 V
4.5 V
5.0 V
1
, each time a reset pulse
1000
Pin 6
Pin 3
Pin 5
4756C–AUTO–09/04
1
(see Figure