1
®
FN8226.1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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ISL88021, ISL88022
Triple Voltage Monitor with Adjustable
Power-On-Reset and Undervoltage/
Overvoltage Monitoring Capability
The ISL88021 and ISL88022 family of devices are
customizable triple voltage-monitoring supervisors that
assert a reset if any of the monitored voltages becomes
non-compliant. They offer popular functions such as
Power-On-Reset timing control with both RESET and
RESET
outputs, Supply Voltage Supervision, both under or
overvoltage detection, and Manual Reset assertion. By
offering these features in a small 8 Ld MSOP package, the
ISL88021 and ISL88022 can lower system cost, reduce
board space requirements and increase the reliability of
systems.
Applying a voltage to V
DD
activates the Power-On-Reset
circuit which holds RESET
low for an adjustable period of
time. This allows the power supply and system oscillator to
stabilize before the processor can execute code.
Low V
DD
detection circuitry protects the user’s system from
low voltage conditions, resetting the system when V
DD
falls
below its minimum preset voltage threshold V
TH1
. Reset
remains asserted until V
DD
returns to its proper operating
level and stabilizes. Two additional voltage monitoring
inputs, V2MON (preset) and V3MON (adjustable), monitor
other supplies to provide reliable system operation.
The ISL88021 V3MON input monitors for undervoltage (UV)
conditions whereas the ISL88022 V3MON input allows
monitoring for overvoltage (OV) conditions. The monitored
voltage on V3MON on either device is compared via a
resistor divider to a 600mV internal reference. Hence, any
voltage more or less positive than this reference can be
accurately monitored to meet specific system level
requirements or to fine-tune the threshold for applications
requiring higher precision.
These devices also let users increase the Power-On-Reset
time-out delay by connecting a capacitor between C
POR
and
ground. This lengthens the period of an internal clock
counter thereby increasing the time between voltage
compliance and reset outputs signaling.
A manual reset input provides debounce circuitry for
minimum reset component count.
Features
• Triple Voltage Monitor and Reset Assertion
•Low V
DD
Detection and Reset Assertion
- Adjustable Reset Threshold Voltages
- 0.6V ±6mV Over -40°C to +85°C
- Reset Signal Valid to V
DD
= 1V
• 140ms Minimum Reset Pulse Delay that is Customizable
Using an External Capacitor
• Both RST and RST Outputs Available
• Undervoltage/Overvoltage Monitoring Capability
• Low 20µA Consumption
• Small 8 Ld MSOP Package
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• Process Control Systems
• Intelligent Instruments
• Embedded Control Systems
• Computer Systems
• Portable/Battery-Powered Equipment
• Multi-Voltage Systems
Pinout
ISL88021, ISL88022
(8 LD MSOP)
TOP VIEW
1
2
3
4
8
7
6
5
V
DD
V2MON
GND
RST
RST
C
POR
V3MON
MR
Data Sheet September 18, 2006
