SUPPLY VOLTAGE
MONITOR
ISSUE 2 – JANUARY 2003
DEVICE DESCRIPTION
The ZSM380 is a three terminal under
v o l t a g e m o n i t or c ir c ui t fo r u s e i n
microprocessor systems. The threshold
voltage of the device has been set to 3.8 volts
making it ideal for 5 volt circuits.
Included in the device is a precise voltage
reference and a comparator with built in
hysteresis to prevent erratic operation. The
ZSM380 features an open collector output
capable of sinking at least l0mA which only
requires a single external resistor to
interface to following circuits.
Operation of the device is guaranteed from
one volt upwards, from this level to the
device threshold voltage the output is held
low providing a power on reset function.
Should the supply voltage, once established,
at any time drop below the threshold level
then the output again will pull low.
The device is available in a TO92 package for
through hole applications as well as SOT223
for surface mount requirements.
ZSM380
FEATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
SOT223 and TO92 packages
Power on reset generator
Automatic reset generation
Low standby current
Guaranteed operation from 1 volt
Wide supply voltage range
Internal clamp diode to discharge
delay capacitor
3.8 volt threshold for 5 volt logic
20mV hysteresis prevents erratic operation
APPLICATIONS
Microprocessor systems
Computers
Computer peripherals
Instrumentation
Automotive
Battery powered equipment
SCHEMATIC DIAGRAM
4-349
ZSM380
ABSOLUTE MAXIMUM RATING
Input Supply Voltage
Offstate Output Voltage
Onstate Output
Sink Current(
Note 1
)
Clamp Diode
Forward Current(
Note 1
)
Operating Junction
Temperature
Operating Temperature
Storage Temperature
-1 to 10V
10V
Internally limited
100mA
150°C
-40 to 85°C
-55 to 150°C
Power Dissipation
TO92
SOT223
780mW
2W(
Note 2
)
TEST CONDITIONS
(T
amb
=25°C for typical values, T
amb
=-40 to 85°C for min/max values (Note3))
COMPARATOR
PARAMETER
Threshold Voltage
High state output (V
cc
increasing)
Threshold Voltage
Low state output (V
cc
decreasing)
Hysteresis
SYMBOL
V
IH
V
IL
V
H
3.7
3.7
0.01
MIN
TYP.
MAX.
UNITS
V
V
V
3.81
3.79
0.02
3.9
3.9
0.05
OUPUT
Output sink saturation:
(V
cc
=3.3V, I
sink
=8.0mA)
(V
cc
=3.3V, I
sink
=2.0mA)
(V
cc
=1.0V, I
sink
=0.1mA)
Onstate output sink current
(V
cc
, Output=3.3V)
Offstate output leakage current
(V
cc
, Output=5V)
Clamp diode forward voltage
(I
f
=10mA)
Propagation delay
(V
in
5V to 3.3V, R
l
=10k, T
amb
=25°C)
I
sink
I
oh
V
f
T
d
0.6
10
27
0.02
1.2
3
V
OL
0.46
0.15
1.0
0.4
0.25
60
0.5
1.5
V
V
V
mA
µ
A
V
µ
s
TOTAL DEVICE
Operating input voltage range
Quiescent input current (V
cc
=5V)
V
cc
I
q
1.0 to 6.5
140
200
V
µ
A
Note:
1. Maximum package power dissipation must be observed.
2. Maximum power dissipation for the SOT223 package is calculated assuming that the device is
mounted on a PCB measuring 2 inches square.
3. Low duty cycle pulse techniques are used during test to maintain junction temperatures as
close to ambient as possible.
4-350
ZSM380
TYPICAL CHARACTERISTICS
500
10
R
l
=10K
T
a
=25°C
400
85°C
25°C
8
Input Current (µA)
300
Output Voltage (V)
-40°C
6
200
4
100
2
0
0
2
4
6
8
10
0
0
2
Input Voltage (V)
Input Voltage
(V)
4
6
8
10
Input Current vs. Input Voltage
50
Output Voltage vs. Input Voltage
R
l
=10K
V
in
=3.3V
40
5
V
in
(V)
Sink Current (mA)
30
-40°C
25°C
20
85°C
3.3
4
2
10
V
out
(V)
0
0
0
0.4
0.8
1.2
1.6
2.0
0
2
4
6
Output Saturation Voltage (V)
Time (µs)
Output I(sink) vs. Output V(sat)
50
V
in
=0V
3.82
Reset Delay Time
Upper Threshold
40
3.81
Forward Current (mA)
Threshold Voltage (V)
30
85°C
25°C
-40°C
3.80
20
3.79
Lower Threshold
10
3.78
0
0
0.4
0.8
1.2
1.6
2.0
3.77
-40
-20
0
20
40
60
80
Forward Voltage (V)
Temperature ( °C)
Clamp Diode I(forward) vs. Voltage
Threshold Voltage vs. Temperature
4-351
100
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