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SUPPLY VOLTAGE

MONITOR

ISSUE 1 – NOVEMBER 1995

ZSM530

DEVICE DESCRIPTION

The ZSM530 is a three terminal under

v o l t a g e   m o n i t o r   c i r c u i t   f o r  u s e   i n

microprocessor systems. The threshold

voltage of the device has been set to 4.3 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

ZSM530 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 SO8 and

SOT223 for surface mount requirements.

FEATURES 

SO8, 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

4.3 volt threshold for 5 volt logic

20mV hysteresis prevents erratic operation

APPLICATIONS

Microprocessor systems

Computers

Computer peripherals

Instrumentation

Automotive

Battery powered equipment

SCHEMATIC DIAGRAM

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TEST CONDITIONS 

(T

amb

=25°C for typical values, T

amb

=-40 to 85°C for min/max values (Note3))

COMPARATOR

PARAMETER

SYMBOL

MIN

TYP.

MAX.

UNITS

Threshold Voltage

High state output (V

cc

 increasing)

V

IH

4.2

4.31

4.4

V

Threshold Voltage

Low state output (V

cc

 decreasing)

V

IL

4.2

4.29

4.4

V

Hysteresis

V

H

0.01

0.02

0.05

V

OUPUT

Output sink saturation:

V

OL

(V

cc

=3.8V, I

sink

=8.0mA)

0.46

1.0

V

(V

cc

=3.8V, I

sink

=2.0mA)

0.15

0.4

V

(V

cc

=1.0V, I

sink

=0.1mA)

0.25

V

Onstate output sink current 

(V

cc

 , Output=3.8V)

I

sink

10

27

60

mA

Offstate output leakage current 

(V

cc 

, Output=5V)

I

oh

0.02

0.5

µ

A

Clamp diode forward voltage

(I

f

=10mA)

V

f

0.6

1.2

1.5

V

Propagation delay 

(V

in

 5V to 3.8V, R

l

=10k, T

amb

=25°C)

T

d

2

µ

s

TOTAL DEVICE

Operating input voltage range

V

cc

1.0 to 6.5

V

Quiescent input current (V

cc

=5V)

I

q

175

260

µ

A

Note:

1. Maximum package power dissipation must be observed.

2. Maximum power dissipation, for the SOT223 and SO8 packages, 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.

ZSM530

ABSOLUTE MAXIMUM RATING

Input Supply Voltage

-1 to 10V

Offstate Output Voltage

10V

Onstate Output 

Sink Current(

Note 1

)

Internally limited

Clamp Diode

Forward Current(

Note 1

)

100mA

Operating Junction 

Temperature

150°C

Operating Temperature

-40 to 85°C

Storage Temperature

-55 to 150°C

Power Dissipation 

TO92

780mW

SOT223

2W(

Note 2

)

SO8

780mW(

Note 2

)

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0

2

4

6

8

10

-40 °C 25 °C

85 °C

100

200

400

300

500

0

2

0

0.8

1.6

2.0

0.4

1.2

0

20

40

50

S

ink Curr

ent (

m

A

)

-40 °C

25 °C

85 °C

0

0.4

2.0

0.8

1.2

1.6

0

40

60

80

20

-40 °C

85 °C

25 °C

4

6

8

10

2

4

6

8

10

0

Output V

o

ltage  

(V)

0

1

2

3

4

2

4

0

V

in (V)

4

5

-40

-20

0

20

40

60

80

4.25

4.20

Temperature (°C)

Forward Voltage (V)

Threshol

d V

o

ltage (V)

Forward Curr

ent 

(m

A

)

In

put C

u

rrent (

µ

A)

Input Voltage

Upper Threshold

Lower Threshold

Input Current vs. Input Voltage

Output Voltage vs. Input Voltage

Output Saturation Voltage vs. Sink Current

Reset Delay Time

Clamp Diode Forward Current vs. Voltage

Threshold Voltage vs. Temperature

Input Voltage

Output Saturation Voltage (V)

V

out (V)

(V)

(V)

Time  (

µ

s)

0

30

10

100

100

4.30

4.35

4.40

R

A

=10K

T

A

=25 °C

R

L

=10K

Ϸ

Ϸ

V

in

=4V

V

in

=0V

ZSM530

TYPICAL CHARACTERISTICS

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ZSM530

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Vcc

Threshold 

Voltage

1 V

Output

Undefined

Output

Undefined

Output

Note 4:  A time delayed reset can be accomplished with the additional Cd.

T

DY

 

=

 

RCd  

ln

1

1

 

 

V

TH

(

mpu

)

V

in

TIMING DIAGRAM

APPLICATION CIRCUIT

T

DY

  =Time (Seconds)

V

TH

 =Microprocessor Reset Threshold

V

in

 =Power 

Supply 

Voltage

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 SO8 Package 

Suffix – N8

 Top 

View 

 SOT223 Package 

Suffix – G

 Top 

View –

   Pin 4 floating or connected to pin 2

CONNECTION  DIAGRAMS

ORDERING INFORMATION

Part Number

Package

Part Mark

ZSM530N8

SO8

ZSM530

ZSM530G

SOT223

ZSM530

ZSM530C

TO92

ZSM530

  TO92  Package Suffix – C

 Bottom 

View   

ZSM530

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