Datasheet MAX4505EUK-T, MAX4505EUA Datasheet (Maxim)

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MAX4505

Fault-Protected, High-Voltage,

Signal-Line Protector

________________________________________________________________

Maxim Integrated Products

1

19-1514; Rev 0; 7/99

General Description

The MAX4505 is a single signal-line protector featuring a
fault-protected input and Rail-to-Rail®signal handling
capability. The input is protected from overvoltage faults
up to ±36V with power on or ±40V with power off. During
a fault condition, the input terminal becomes an open cir­cuit and only nanoamperes of leakage current flow from
the source, while the switch output (AOUT) furnishes typ­ically 19mA from the appropriate polarity supply to the
load. This ensures an unambiguous rail-to-rail output
when a fault begins and ends.

The MAX4505 protects both unipolar and bipolar analog
signals using either unipolar (+9V to +36V) or bipolar
(±8V to ±18V) power supplies. The device has no logic
control inputs; the protector is always on when the sup­plies are on. On-resistance is 100Ω max, and on-leakage
is less than 0.5nA at TA= +25°C. The MAX4505 is avail­able in 5-pin SOT23 and 8-pin µMAX packages.

Applications

Process Control Systems
Hot-Insertion Boards/Systems
Data-Acquisition Systems
Redundant/Backup Systems
ATE Equipment
Sensitive Instruments

Features

♦ Overvoltage Protection

±40V with Power Off
±36V with Power On

♦ Open Signal Paths with Power Off
♦ Output Clamps to Either Rail with an Input

Overvoltage

♦ 100Ω max On-Resistance
♦ 10ns Overvoltage Turn-On Delay
♦ No Latchup During Power Sequencing
♦ Rail-to-Rail Signal Handling
♦ 500Ω Output Clamp Resistance During

Overvoltage

♦ Tiny 5-Pin SOT23 Package

IN AIN

R

OUT

OUTAOUT

RAIL

SENSOR

V-

V- V+

V-

V+

V+

MAX4505

Typical Operating Circuit Pin Configurations

V+

N.C.AOUT

15V-AIN

MAX4505

SOT23-5

TOP VIEW

2

34

Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.

Pin Configurations continued at end of data sheet.

Ordering Information

PART TEMP. RANGE

PIN-

PACKAGE

TOP

MARK

ADLW

5 SOT23-5-40°C to +85°CMAX4505EUK-T

MAX4505EUA -40°C to +85°C 8 µMAX —

MAX4505

Fault-Protected, High-Voltage,
Signal-Line Protector

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED OPERATING GUIDELINES

ELECTRICAL CHARACTERISTICS—Dual Supplies

(V+ = +15V, V- = -15V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 3)

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 rating conditions for extended periods may affect device reliability.

(Voltages referenced to GND)

V+........................................................................-0.3V to +44.0V

V- .........................................................................-44.0V to +0.3V

V+ to V-................................................................-0.3V to +44.0V

AIN, AOUT (Notes 1, 2) .......................................................±44V

AIN Overvoltage with Power On ..........................................±36V

AIN Overvoltage with Power Off ..........................................±40V

Continuous Current into Any Terminal..............................±30mA

Peak Current into Any Terminal

(pulsed at 1ms, 10% duty cycle)...............................±70mA

Continuous Power Dissipation (TA= +70°C)

5-Pin SOT23-5 (derate 7.10mW/°C above +70°C) ...571mW

8-Pin µMAX (derate 4.10mW/°C above +70°C) ........330mW

Operating Temperature Ranges

MAX4505C_ _ ..................................................0°C to +70°C

MAX4505E_ _ ...............................................-40°C to +85°C

Storage Temperature Range .............................-55°C to +150°C

Lead Temperature (soldering, 10sec) .............................+300°C

V+ to GND..............................................................-0.3V to +40V

V- to GND ...............................................................-32V to +0.3V

V+ to V- ..................................................................................40V

AIN.......................................................................................±40V

AOUT...............................................................................V+ to V-

AIN to AOUT.........................................................40V differential

Continuous Current into Any Terminal ..............................≤30mA

Peak Current into Any Terminal

(pulsed at 1ms, 10% duty cycle) ...............................≤70mA

T

A

PARAMETER SYMBOL MIN TYP MAX UNITSCONDITIONS

E

Fault-Free Analog Signal Range
(Note 4)

V

AIN

V- V+ VV

AIN

= ±15V

E 125

Ω

+25°C

Analog Signal-Path Resistance R

ON

65 100

V

AIN

= ±10V, I

AOUT

= 1mA

E -20 20

nA

+25°C

Signal-Path Leakage Current
(Note 5)

I

AOUT(ON)

-0.5 0.5

V

AOUT

= ±10V, V

AIN

= ±10V

or floating

pF+25°CInput Capacitance C

AIN

20V

AIN

= 0, f = 1MHz

E -40 40

V

E

Fault-Protected Analog Signal
Range (Notes 4, 6)

V

AIN

-36 36Applies with power on

Applies with power off

E -200 200

nA

+25°C

Input Signal-Path Leakage
Current, Supplies On

I

AIN(ON)

-20 0.1 20

V

AIN

= ±25V, V

AOUT

= open

E -500 500

nA

+25°C

Input Signal-Path Leakage
Current, Supplies Off

I

AIN(OFF)

-20 0.2 20

V

AIN

= ±40V, V

AOUT

= open

V+ = 0, V- = 0

+25°C -26 -19 -13

mA

+25°C

Output Clamp Current,
Supplies On

I

AOUT

13 19 26V

AIN

= 25V

V

AIN

= -25V

+25°C 0.4 1.0

kΩ

+25°C

Output Clamp Resistance,
Supplies On

R

AOUT

0.5 1.0

I

AOUT

= 1mA

V

AIN

= 25V

V

AIN

= -25V

ns+25°C

±Fault Output Turn-On
Delay Time

10RL= 10kΩ, V

AIN

= ±25V

ANALOG SWITCH

FAULT PROTECTION

Note 1: The AOUT pin is not fault protected. Signals on AOUT exceeding V+ or V- are clamped by internal diodes. Limit forward

diode current to maximum current rating.

Note 2: The AIN pin is fault protected. Signals on AIN exceeding -36V to +36V may damage the device. These limits apply with

power applied to V+ or V-, or ±40V with V+ = V- = 0.

MAX4505

Fault-Protected, High-Voltage,

Signal-Line Protector

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS—Single Supply

(V+ = +12V, V- = 0, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 3)

ELECTRICAL CHARACTERISTICS—Dual Supplies (continued)

(V+ = +15V, V- = -15V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)

Note 3: The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column.
Note 4: See Fault-Free Analog Signal Range vs. Supply Voltage graph in the

Typical Operating Characteristics

.

Note 5: Leakage parameters are 100% tested at maximum rated hot temperature and guaranteed by correlation at T

A

= +25°C.

Note 6: Guaranteed by design.
Note 7: Guaranteed by testing with dual supplies.
Note 8: SOT packaged parts are 100% tested at +25°C. Limits at the maximum rated temperature are guaranteed by design and

correlation limits at +25°C. Leakage tests are typical for SOT packaged parts.

EPower-Supply Range V+, V- ±8 ±18 V

T

A

E

PARAMETER SYMBOL MIN TYP MAX UNITS

240

µA

CONDITIONS

+25°C

I+

45 150

V

AIN

= 15V

E

Fault-Free Analog Signal Range
(Note 4)

V

AIN

0V+VV

AIN

= 12V

E -20 20

nA

+25°C

T

A

E

Signal-Path Leakage Current
(Note 5)

I

AOUT(ON)

PARAMETER SYMBOL MIN TYP MAX UNITS

250

-0.5 0.05 0.5

V

AIN

= 10V or floating

Ω

Applies with power off

CONDITIONS

+25°C

Analog Signal-Path Resistance R

ON

125 200

E

V

AIN

= 10V, I

AOUT

= 1mA

E -40 40

E -200 200

V

E

Fault-Protected Analog Signal
Range (Notes 4, 6)

V

AIN

-36 36Applies with power on

µs+25°C

ns

nA

+25°C

+25°C

±Fault Output Turn-On
Delay Time

Input Signal-Path Leakage
Current, Supply On (Note 7)

10

I

AIN(ON)

-20 0.2 20

V

AIN

= ±25V, V

AOUT

= 0

-500 500

±Fault Recovery Time

RL= 10kΩ, V

AIN

= 25V

2.5

nA

+25°C

Input Signal-Path Leakage
Current, Supply Off (Note 7)

I

AIN(OFF)

RL= 10kΩ, V

AIN

= 25V

-20 0.2 20

V

AIN

= ±40V

mA+25°C

Output Clamp Current,
Supply On

I

AOUT

3 5.5 10V

AIN

= 25V

kΩ+25°C

Output Clamp Resistance,
Supply On

R

AOUT

1.0 2.5V

AIN

= ±25V

VEPower-Supply Range V+, V- +9 +36

µA

+25°C

Power-Supply Current I+

525

V

AIN

= 12V

E 40

+25°C±Fault Recovery Time 25 µsRL= 10kΩ, V

AIN

= ±25V

E -240

+25°C

Power-Supply Current

I-

-150 -45

V

AIN

= 15V

POWER SUPPLY

ANALOG SWITCH

FAULT PROTECTION

POWER SUPPLY

MAX4505

Fault-Protected, High-Voltage,
Signal-Line Protector

4 _______________________________________________________________________________________

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

0

20

60

40

100

120

80

140

-20 -10 -5-15 0 5 10 15 20

ON-RESISTANCE vs. OUTPUT VOLTAGE

(DUAL SUPPLIES)

MAX4505 toc01

V

OUT_

(V)

R

ON

(Ω)

V+ = +18V

V- = -18V

V+ = +15V

V- = -15V

V+ = +10V

V- = -10V

V+ = +8V

V- = -8V

0

50

150

100

200

250

010155 20253035

ON-RESISTANCE vs. OUTPUT VOLTAGE

(SINGLE SUPPLY)

MAX4505 toc02

V

OUT_

(V)

R

ON

(Ω)

V+ = +12V

V+ = +9V

V+ = +20V

V+ = +30V

V+ = +36V

V- = 0

20

0

40

80

60

100

120

-15 -5 0-10 5 10 15

ON-RESISTANCE vs. OUTPUT VOLTAGE

AND TEMPERATURE (DUAL SUPPLIES)

MAX4505 toc03

V

OUT_

(V)

R

ON

(Ω)

V+ = +15V

V- = -15V

TA = +125°C

TA = +85°C

TA = +70°C

TA = -55°C

TA = -40°C

TA = +25°C

0

50

150

100

200

250

0462 8 10 12

ON-RESISTANCE vs. OUTPUT VOLTAGE

AND TEMPERATURE (SINGLE SUPPLY)

MAX4505 toc04

V

OUT_

(V)

R

ON

(Ω)

TA = +125°C

TA = +85°C

TA = +70°C

TA = -55°C

V+ = +12V
V- = 0

TA = -40°C

TA = +25°C

-20

-15

-10

-5

0

5

10

15

20

-30 -10-20 0 102030

OUTPUT TRANSFER CHARACTERISTICS

(DUAL SUPPLIES)

MAX4505 toc07

INPUT VOLTAGE (V)

OUTPUT CLAMP VOLTAGE (V)

(V+ = +18V, V- = -18V)

(V+ = +15V, V- = -15V)

(V+ = +10V, V- = -10V)
(V+ = +8V, V- = -8V)

(V+ = +8V, V- = -8V)

(V+ = +10V, V- = -10V)

(V+ = +15V, V- = -15V)

(V+ = +18V, V- = -18V)

OUTPUT LOAD = 1MΩ

INPUT VOLTAGE
LINEARLY SWEPT
BETWEEN -30V
AND +30V

0

0.1

0.2

0.4

0.3

0.6

0.5

0.7

-40 -20 -10-30 0 1020304050607080

OUTPUT CLAMP RESISTANCE

(SUPPLIES ON) vs. TEMPERATURE

MAX4505 toc05

TEMPERATURE (°C)

R

OUT

(kΩ)

V+ = +15V
V- = -15V
V

IN

= ±2.5V

VIN = -25V

VIN = +25V

-25

-15

-20

0

-5

-10

5

10

20

15

25

-55 -25 -10-40 5 20 35 50 65 80 95 110 125

OUTPUT CLAMP CURRENT (SUPPLIES ON)

vs. TEMPERATURE

MAX4505 toc06

TEMPERATURE (°C)

I

OUT

(mA)

V- = -15V

V+ = +15V

0

5

10

15

20

25

30

35

40

0105 152025303540

OUTPUT TRANSFER CHARACTERISTICS

(SINGLE SUPPLY)

MAX4505 toc08

INPUT VOLTAGE (V)

OUTPUT CLAMP VOLTAGE (V)

INPUT VOLTAGE LINEARLY SWEPT
BETWEEN 0 AND 36V

OUTPUT LOAD = 1MΩ
V- = 0

V+ = +9V

V+ = +25V

V+ = +36V

V+ = +15V

V+ = +12V

-20

-15

-10

-5

0

5

10

15

20

-20 -10-15 -5 0 5 10 15 20

FAULT-FREE ANALOG SIGNAL RANGE

vs. SUPPLY VOLTAGE

MAX4505 toc09

INPUT VOLTAGE (V)

OUTPUT VOLTAGE (V)

MAX4505

Fault-Protected, High-Voltage,

Signal-Line Protector

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

0.01p

0.1p

10p

1p

1n

10n

100p

100n

-55 -5 20-30 45 70 95 120 145

FAULT-FREE OUTPUT LEAKAGE CURRENT

(SUPPLIES ON)

MAX4505 toc10

TEMPERATURE (°C)

LEAKAGE CURRENT (A)

V

OUT

= ±10V

I

OUT

(V+ = +15V, V- = -15V)

I

OUT

(V+ = +12V, V- = 0)

0.1p

1p

100p

10p

10n

100n

1n

1µ

-55 -15 5-35 25 45 65 85 105 125

INPUT FAULT LEAKAGE CURRENT

(SUPPLIES ON)

MAX4505 toc11

TEMPERATURE (°C)

LEAKAGE CURRENT (A)

I

IN

AT +25V (V+ = +12V, V - = 0)

I

IN

AT +25V (V+ = +15V, V- = -15V)

-80

-60

-40

0

-20

40

20

80

60

-40 -20 -10-30 0 1020304050607080

POWER SUPPLY CURRENT

vs. TEMPERATURE

MAX4505 toc12

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

I+ SINGLE SUPPLY +12V

I+

I-

V+ = +15V
V- = -15V

-60

-20

I-

I+

-40

20

0

40

60

-15 -5 0-10 5 10 15

SUPPLY CURRENT vs. INPUT VOLTAGE

MAX4505 toc13

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

10

-100

0.01 1 100.1 1000100

FREQUENCY RESPONSE

-90

MAX4505 toc15

FREQUENCY (MHz)

BANDWIDTH (dB)

-80

-70

-60

-50

-40

-30

-20

-10

0

V+ = +15V
V- = -15V

IN_

10V/div

+15V

-15V

+15V

0

-15V

10V/div

OUT_

5µs/div

FAULT-FREE SIGNAL PERFORMANCE

MAX4505 toc16

FAULT-FREE RAIL-TO-RAIL SIGNAL HANDLING
WITH ±15V SUPPLIES

IN_

+25V

0

+15V

0

-25V

-15V

±25V OVERVOLTAGE INPUT WITH THE OUTPUT
CLAMPED AT ±15V

0

OUT_

5µs/div

INPUT OVERVOLTAGE

vs. OUTPUT CLAMPING

MAX4505 toc17

IN_

5V/div

0

+16V

+15V

0

OUT_

5V/div

5µs/div

FAULT RECOVERY

MAX4505 toc18

V+ = +15V
V- = -15V

_______________Detailed Description

The MAX4505 protects other ICs from overvoltage by
clamping its output voltage to the supply rails. If the
power supplies to the device are off, the device clamps
the output to 0V. The MAX4505 provides protection for
input signals up to ±36V with the power supplies on
and ±40V with the power supplies off.

The MAX4505 protects other integrated circuits (ICs)
connected to its output from latching up. Latchup is
caused by parasitic SCR(s) within the IC turning on,
and can occur when the supply voltage applied to the
IC exceeds the specified operating range. Latchup can

also occur when signal voltage is applied before the
power-supply voltage. When in a latchup state, the cir­cuit draws excessive current and may continue to draw
excessive current even after the overvoltage condition
is removed. A continuous latchup condition may dam­age the device permanently. Such “faults” are com­monly encountered in modular control systems where
power supplies to interconnected modules may be
interrupted and reestablished at random. Faults can
happen during production testing, maintenance, start­up, or a power failure.

Figure 1 shows the normal complementary pair (N1
and P1) found in many common analog switches. In
addition to these transistors, the MAX4505 also con­tains comparators, sensing circuitry, and clamping cir­cuitry to control the state of N1 and P1. During normal
operation, N1 and P1 remain on with a typical 65Ω on-
resistance between IN and OUT.

The on-board comparators and sensing circuitry moni­tor the input voltage for possible overvoltage faults.
Two clamp circuits limit the output voltage to within the
supply voltages. When the power supplies are off, any
input voltage applied at IN turns off both N1 and P1,
and OUT is clamped to 0V.

Normal Operation

When power is applied, the protector acts as a resistor
in series with the signal path. A voltage on the “input”
side of the switch conducts through the protector to the
output (Figure 2).

When the output load is resistive, it draws current
through the protector. The internal resistance is typical­ly less than 100Ω. The MAX4505 does not affect high­impedance loads. The protector’s path resistance is a
function of the supply voltage and the signal voltage
(see

Typical Operating Characteristics

).

MAX4505

Fault-Protected, High-Voltage,
Signal-Line Protector

6 _______________________________________________________________________________________

Pin Description

Figure 1. Simplified Internal Structure

µMAXSOT

AIN Analog Fault-Protected Input31

V-

N.C.

AOUT

V+

NAME

Negative Supply Voltage Input45

No Connection. Not internally connected.2, 5, 6, 74

Analog Signal Output13

Positive Supply Voltage Input82

FUNCTION

PIN

-15V

-15V

IN

+15V

+15V

COMPARATOR

N3

SENSE

SWITCH

P3

SENSE

SWITCH

COMPARATOR

N-CHANNEL

DRIVER

P-CHANNEL

DRIVER

-V(-15V)

N2

CLAMP

N1

CLAMP

P2

P1

+V(+15V)

OUT

Fault Protection with Power Off

When power is off (i.e., V+ = V- = 0), the protector is a
virtual open circuit. The output stays at 0 with up to
±40V applied to the input.

Fault Protection with Power On

A fault condition exists when the voltage on AIN
exceeds either supply rail. This definition is valid when
power is on or off, as well as during all states while
power ramps up or down.

Applications Information

Supplying Power Through External ICs

The MAX4505 has low supply current (<250µA), which
allows the supply pins to be driven by other active cir­cuitry instead of connected directly to the power
sources. In this configuration, the part can be used as a
driven fault-protected switch with V+ or V- used as the

control pins. For example, with the V- pin grounded, the
output of a CMOS gate can drive the V+ pin to turn the
device on and off. Ensure that the driving source(s)
does not drive the V+ pin more negative than the V- pin.

Protector as Circuit Elements

Figure 3 shows a MAX4505 used in front of a MAX338
unprotected 1-to-8 multiplexer. With supplies at ±15V,
V

AOUT

of the MAX4505 clamps to ±15V and V

OUT

of

the MAX338 goes to ±14V. With supplies off, V

AOUT

goes to 0 even though the input remains at ±25V.

Multiplexer and Demultiplexer

The MAX4505 can be used in series with the output of a
MAX4508 (1-to-8 multiplexer) to act as multiplexer or
demultiplexer. The MAX4508 is a fault-protected multi­plexer whose inputs are designed to interface with harsh
environments; however, its common output is not fault
protected if connected to outside signals (i.e., demulti­plexer use). If the common output can see fault signals,
then it needs to be protected, and the MAX4505 can be
added to provide complete protection.

As seen in Figure 4, the signal input can now be put
into pin 3 of the MAX4505 (new common output for sys­tem), and outputs can be taken at MAX4508 pins 4 to
7, and 9 to 12. This is the classic demultiplexer opera­tion. This system now has full protection on both of the
multiplexers’ inputs and outputs.

Measuring Path Resistance

Measuring path resistance requires special techniques,
since path resistance varies dramatically with the AIN
and AOUT voltages relative to the supply voltages. Do
not use conventional ohmmeters. Their applied voltage
and currents are usually unpredictable. The true resis-

MAX4505

Fault-Protected, High-Voltage,

Signal-Line Protector

_______________________________________________________________________________________ 7

Figure 2. Application Circuit

Figure 3. Protecting a MAX338 with a MAX4505

Figure 4. Demultiplexer Application Using MAX4505
with MAX4508

MAX4505

V- V- V+V+

V

IN

AIN

AOUT

R

OUT

+25V 3

-15V

+3V

OV

1

2

87+15V

MAX4505

6

4

5

+5V

-5V

1

A

O

EN

2

V-

3

MAX338

4

NO1

NO2

5

NO3

6

NO4

7

V

8

OUT

GND

NO5

NO6

NO7

NO8

16

A1

15

A2

14

+15V

V+

13

12

11

10

9

NEW COM

-15V

+3V

O

1

2

87+15V

MAX4505

3

4

6

5

+5V

-15V

1

AO

2

EN

V-

3

MAX4508

4

NO1

NO2

5

6

NO3

7

NO4

COM

8

GND

NO5

NO6

NO7

NO8

16

A1

15

A2

14

+15V

V+

13

12

11

10

9

MAX4505

Fault-Protected, High-Voltage,
Signal-Line Protector

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

8

_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

tance is a function of the applied voltage, which is
dramatically altered by the ohmmeter itself. Autoranging
ohmmeters are particularly unreliable.

Figure 5 shows a circuit that gives reliable results. This
circuit uses a 100mV voltage source and a low-voltage­drop ammeter as the measuring circuit, and an
adjustable supply to sweep the analog voltage across
its entire range. The ammeter must have a voltage drop
of less than 1mV (up to the maximum test current) for
accurate results. A Keithley model 617 electrometer
has a suitable ammeter circuit, appropriate ranges, and
a built-in voltage source designed for this type of mea­surement. Find the path resistance by setting the ana­log voltage, measuring the current, and calculating the
path resistance. Repeat the procedure at each analog
and supply voltage.

Note that it is important to use a voltage source of
100mV or less. As shown in Figure 5, this voltage and
the V

AIN

voltage form the V

AOUT

voltage. Using higher

voltages could cause A

OUT

to go into a fault condition

prematurely.

Figure 5. Path-Resistance Measuring Circuit

TRANSISTOR COUNT: 56

Pin Configurations (continued)

N.C.

N.C.V-

1

2

87V+

N.C.N.C.

AIN

AOUT

µMAX

3

4

6

5

MAX4505

TOP VIEW

Chip Information

V

A

AOUT

100mV

MAX4505

V

AIN

AIN

ADJUSTABLE

ANALOG

VOLTAGE

V- V+V+

PATH RESISTANCE = 100mV/A

AOUT