ZXCM809
ZXCM810
VERY LOW POWER MICROPROCESSOR RESET DEVICES
DESCRIPTION
The ZXCM809/810 are three terminal supervisory
circuits used to monitor the power supplies in
microprocessor and digital systems. They provide a
high performance economical solution when used
with 5V, 3V or lower powered circuits. Reset thresholds
suitable for operation with a variety of supply voltages
are available.
These devices provide a reset signal whenever the
supply voltage falls below a preset threshold, keeping
it asserted for a minimum delay period of 140ms after
the supply has risen above the reset level. The
ZXCM809 has an active-low RESET output (which is
guaranteed to be in the correct state for supplies down
to 1V), while the ZXCM810 has an active-high RESET
output.
The reset comparator has in built hysteresis to prevent
erratic operation and is designed to ignore supply
transients. Low supply current (typically 2 A) makes
the ZXCM809/810 devices ideal for use in portable
equipment. They are available in a 3-pin SOT23 surface
mount package with an industry standard pinout.
APPLICATIONS
•
Computer systems
•
Controllers
•
Instrumentation
•
Microprocessor power monitoring
•
Microcontroller power monitoring
•
Power supplies
•
Portable/Battery-powered equipment
•
Automotive
APPLICATION CIRCUIT
FEATURES
•
Enhanced alternative to MAX809/810 and similar
parts
v
cc
v
cc
ZXCM
Reset
Output
v
cc
Micro
Reset
Input
•
Precision monitoring of 5V, 3.3V, 3V power supply
voltages
•
1% threshold tolerance
•
2µA typical supply current
•
140ms minimum power on reset pulse width
•
RESET LOW Output (ZXCM809)
•
RESET HIGH Output (ZXCM810)
•
Push - Pull CMOS Output
•
Power supply transient immunity
•
No latch up
•
No external components
•
3-Pin SOT23 package
Gnd
Gnd
ISSUE 2 - JANUARY 2003
1
ZXCM809
ZXCM810
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage with respect to G
ND
V
CC
RESET, RESET
Input Current, V
CC
Output Current
Rate of Rise, V
CC
Continuous Power Dissipation
Operating Temperature Range
Storage Temperature Range
-0.3V to 7.0V
-0.3V to (V
CC
+ 0.3V)
20mA
20mA
250V/ s
500mW
-55°C to +125°C
-65°C to +150°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum
conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
TEST CONDITIONS (unless otherwise stated) V
CC
=
full range, T
A
= -55°C to +125°C
SYMBOL
PARAMETER
CONDITIONS
MIN
V
R
I
CC
V
TH
V
CC
Range
Supply Current
Reset Threshold
Suffix L; T
A
=25°C
Suffix M; T
A
=25°C
Suffix J; T
A
=25°C
Suffix T; T
A
=25°C
Suffix S; T
A
=25°C
Suffix R; T
A
=25°C
V
THT
V
TH
/°C
V
D
V
TO
Reset Threshold
Tolerance
Reset Threshold Temp.
Coefficient
V
CC
to Reset Delay
Reset Active Timeout
Period
140
T
A
=25°C
T
A
=-55° to 125°C
4.58
4.34
3.96
3.05
2.90
2.60
T
A
=0° to 70°C
T
A
=-55° to 125°C
1.0
1.2
2
4.63
4.38
4.00
3.08
2.93
2.63
1
5
50
30
560
LIMITS
TYP
MAX
5.5
5.5
5
4.68
4.42
4.04
3.11
2.96
2.66
V
V
V
V
V
V
%
%
ppm/°C
s
ms
V
V
A
UNITS
ISSUE 2 - JANUARY 2003
2
ZXCM809
ZXCM810
ELECTRICAL CHARACTERISTICS ZXCM809
TEST CONDITIONS (unless otherwise stated) V
CC
= full range, T
A
= -55°C to +125°C
SYMBOL
PARAMETER
CONDITIONS
MIN
V
OL
Reset Output Voltage
Low
V
CC
>1V, I
OL
=100 A (0 to 85°C)
V
CC
>1.2V, I
OL
=200 A
V
TH
>V
CC
>2.5V, I
OL
=2.7mA
V
OH
Reset Output Voltage
High
V
CC
>V
TH
max, I
OH
=1mA
0.8V
CC
LIMITS
TYP
MAX
0.3
0.3
0.4
V
V
V
V
UNITS
ELECTRICAL CHARACTERISTICS ZXCM810
TEST CONDITIONS (unless otherwise stated) V
CC
= full range, T
A
= -55°C to +125°C
SYMBOL
PARAMETER
CONDITIONS
MIN
V
OL
V
OH
Reset Output Voltage
Low
Reset Output Voltage
High
V
CC
>V
TH
max, I
OL
=2mA
V
CC
>V
TH
max, I
OL
=2.7mA
V
CC
>1.5V, I
OH
=150 A
V
CC
>V
TH
>2.5V, I
OH
=1mA
0.8V
CC
0.8V
CC
LIMITS
TYP
MAX
0.3
0.4
V
V
V
V
UNITS
Note: Device testing is performed at TA=25°C. Device thermal performance is guaranteed by design
TYPICAL CHARACTERISTICS
ISSUE 2 - JANUARY 2003
3
ZXCM809
ZXCM810
TYPICAL APPLICATIONS
ISSUE 2 - JANUARY 2003
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ZXCM809
ZXCM810
APPLICATIONS INFORMATION
Negative going V
CC
transients
The ZXCM809/810 are, to a good degree, immune to
short duration negative going supply transients. Under
certain circumstances very brief transients are allowed
without inappropriate false triggering of the reset
circuit. The response to supply transients is shown in
the Noise Immunity graph in the typical characteristics.
The graph indicates the typical allowable transient
duration for a specified threshold overdrive such that a
reset pulse is not generated. Addition of a bypass
capacitor, e.g. 0.1 F, as close as possible to the V
CC
pin
will provide extra transient immunity.
Reset valid down to very low supply voltages
With V
CC
between 0V and 1V the output of the
ZXCM809/810 may be in an undefined state. In many
systems this is inconsequential as the microprocessor,
and other circuits, will be inoperative with supplies this
low. In applications where this is important, the
addition of an external resistor ensures that the reset
output remains valid for V
CC
< 1V. The resistor value is
non critical: a value of 100k is recommended. For the
ZXCM809 the resistor should be applied between reset
output and ground: for the ZXCM810 between reset
output and V
CC
. Figure 1 shows the connection
diagram for the ZXCM devices in these configurations.
Figure 1
Circuit for operation of ZXCM with reset valid down to very low supply voltage.
ISSUE 2 - JANUARY 2003
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