X4003-05 Datasheet, PDF (1/16 Pages) Intersil Corporation – Selectable watchdog timer

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X4003, X4005
FN8113.2
CPU Supervisor
These devices combine three popular functions; Power-on
Reset Control, Watchdog Timer and Supply Voltage
Supervision. This combination lowers system cost, reduces
board space requirements and increases reliability.
Applying power to the device activates the power-on reset
circuit which holds RESET/RESET active for a period of
time. This allows the power supply and oscillator to stabilize
before the processor can execute code.
The Watchdog Timer provides an independent protection
mechanism for microcontrollers. When the microcontroller
fails to restart a timer within a selectable time out interval,
the device activates the RESET/RESET signal. The user
selects the interval from three preset values. Once selected,
the interval does not change, even after cycling the power.
The device’s low V_CC detection circuitry protects the user’s
system from low voltage conditions, resetting the system
when V_CC falls below the minimum V_CC trip point.
RESET/RESET is asserted until V_CC returns to proper
operating level and stabilizes. Five industry standard V_TRIP
thresholds are available; however, Intersil’s unique circuits
allow the threshold to be reprogrammed to meet custom
requirements, or to fine-tune the threshold for applications
requiring higher precision.
Block Diagram
Features
• Selectable watchdog timer
- Select 200ms, 600ms, 1.4s, off
• Low V_CC detection and reset assertion
- Five standard reset threshold voltages nominal 4.62V,
4.38V, 2.92V, 2.68V, 1.75V
- Adjust low V_CC reset threshold voltage using special
programming sequence
- Reset signal valid to V_CC = 1V
• Low power CMOS
- 12µA typical standby current, watchdog on
- 800nA typical standby current watchdog off
- 3mA active current
• 400kHz I²C interface
• 1.8V to 5.5V power supply operation
• Available packages
- 8 Ld SOIC
- 8 Ld MSOP
• Pb-free available (RoHS compliant)
Pinout
X4003, X4005
(8 LD SOIC, MSOP)
TOP VIEW
NC ¹
NC 2
RESET/RESET* ³
V_SS
4
8
V_CC
7 _WP
6 SCL
5 SDA
*RESET APPLIES TO X4003
RESET APPLIES TO X4005
WP
SDA
SCL
V_CC
WATCHDOG TRANSITION
DETECTOR
DATA
REGISTER
COMMAND
DECODE AND
CONTROL
LOGIC
V_CC THRESHOLD
RESET LOGIC
CONTROL
REGISTER
+
V_TRIP
-
WATCHDOG
TIMER RESET
RESET AND
WATCHDOG
TIMEBASE
POWER-ON AND
LOW VOLTAGE
RESET
GENERATION
RESET (X4003)
RESET (X4005)
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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