CAT1027WI-25-T3 ON Semiconductor, CAT1027WI-25-T3 Datasheet - Page 7

• Manufacturer Part Number: CAT1027WI-25-T3
• Description: Supervisory Circuits CPU w/2K
• Manufacturer: ON Semiconductor

Specifications of CAT1027WI-25-T3

• Product Category: Supervisory Circuits
• Rohs: yes
• Number Of Voltages Monitored: 1
• Monitored Voltage: 3 V, 3.3 V, 5 V
• Undervoltage Threshold: 2.55 V
• Overvoltage Threshold: 2.7 V
• Manual Reset: Not Resettable
• Watchdog: Watchdog
• Supply Voltage - Max: 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-8 Wide
• Maximum Power Dissipation: 1000 mW
• Minimum Operating Temperature: - 40 C
• Supply Current (typ): 3000 uA
• Supply Voltage - Min: 2.7 V

Reset Controller Description
controllers ensure correct system operation during
brownout and power up/down conditions. They are
configured with open drain RESET outputs.
V
outputs for approximately 200 ms (t
V
to drive the reset outputs. At this point the reset outputs will
be pulled up or down by their respective pull up/down
resistors.
when V
so long as V
to ignore the fast negative going V
(glitches).
Manual Reset Capability
reset input. The input is edge triggered; that is, the RESET
input will initiate a reset timeout after detecting a high to low
transition.
timer will begin to time the reset interval. If external reset is
shorter than 200 ms, Reset outputs will remain active at least
200 ms.
Monitoring Two Voltages
sensor, V
low whenever the input voltage is below 1.25 V. The
auxiliary voltage monitor timing is shown in Figure 2.
can be set to monitor a second supply in the system. The
circuit shown in Figure 3 provides an externally adjustable
threshold voltage, V
The low leakage current at V
value resistors, to reduce the system power consumption.
The V
output to generate a reset condition when either of the
supplies is invalid. In other applications, V
used to interrupt the system controller for an impending
power failure notification.
CC
TH
The CAT1026 and CAT1027 precision RESET
During power−up, the RESET outputs remain active until
During power−down, the RESET outputs will be active
Reset output timing is shown in Figure 1.
The RESET pin can operate as reset output and manual
When RESET I/O is driven to the active state, the 200 ms
The CAT1026 and CAT1027 feature a second voltage
By using an external resistor divider the sense circuitry
. After the t
reaches the V
LOW
CC
SENSE
falls below V
output can be externally connected to the RESET
CC
is > 1.0 V (V
PURST
, which drives the open drain V
TH
TH_ADJ
threshold and will continue driving the
timeout interval, the device will cease
TH
. The RESET output will be valid
RVALID
to monitor the auxiliary voltage.
SENSE
). The device is designed
allows the use of large
PURST
CC
LOW
transient pulses
) after reaching
signal can be
LOW
DEVICE OPERATON
http://onsemi.com
output
7
Data Protection
to solve many of the data corruption issues that have long
been associated with serial EEPROMs. Data corruption
occurs when incorrect data is stored in a memory location
which is assumed to hold correct data.
embedded EEPROM is disabled for all operations,
including write operations. If the Reset output(s) are active,
in progress communications to the EEPROM are aborted
and no new communications are allowed. In this condition
an internal write cycle to the memory can not be started, but
an in progress internal nonvolatile memory write cycle can
not be aborted. An internal write cycle initiated before the
Reset condition can be successfully finished if there is
enough time (5 ms) before V
of 2 V.
power supply voltage during the memory internal write
operation, the system controller should monitor the
unregulated DC power. Using the second voltage sensor,
V
CAT1026 and CAT1027 signals an impending power failure
by setting V
Watchdog Timer
for microcontrollers. During a system failure, the CAT1027
device will provide a reset signal after a time−out interval of
1.6 seconds for a lack of activity. CAT1027 is designed with
the Watchdog timer feature on the WDI pin. If WDI does not
toggle within 1.6 second intervals, the reset condition will be
generated on reset output. The watchdog timer is cleared by
any transition on monitored line.
not count and will stay cleared.
SENSE
The CAT1026 and CAT1027 devices have been designed
Whenever the device is in a Reset condition, the
In addition, to avoid data corruption due to the loss of
The Watchdog Timer provides an independent protection
As long as reset signal is asserted, the watchdog timer will
, to monitor an unregulated power supply, the
LOW
low.
CC
reaches the minimum value