19-1514; Rev 0; 7/99
Fault-Protected, High-Voltage,
Signal-Line Protector
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.
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
Applications
Process Control Systems
Hot-Insertion Boards/Systems
Data-Acquisition Systems
Redundant/Backup Systems
Ordering Information
PART
TEMP. RANGE
PINPACKAGE
TOP
MARK
MAX4505EUK-T
-40°C to +85°C
5 SOT23-5
ADLW
MAX4505EUA
-40°C to +85°C
8 µMAX
—
ATE Equipment
Sensitive Instruments
Typical Operating Circuit
Pin Configurations
TOP VIEW
V-
V-
V+
MAX4505
V-
V+
AIN 1
V+
V+ 2
5
V-
4
N.C.
MAX4505
RAIL
SENSOR
AOUT 3
IN
AIN
AOUT
OUT
SOT23-5
ROUT
Pin Configurations continued at end of data sheet.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX4505
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.
MAX4505
Fault-Protected, High-Voltage,
Signal-Line Protector
ABSOLUTE MAXIMUM RATINGS
(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
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.
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.
RECOMMENDED OPERATING GUIDELINES
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
ELECTRICAL CHARACTERISTICS—Dual Supplies
(V+ = +15V, V- = -15V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
TA
MIN
E
V-
TYP
MAX
UNITS
V+
V
100
Ω
ANALOG SWITCH
Fault-Free Analog Signal Range
(Note 4)
VAIN
VAIN = ±15V
Analog Signal-Path Resistance
RON
VAIN = ±10V, IAOUT = 1mA
Signal-Path Leakage Current
(Note 5)
Input Capacitance
IAOUT(ON)
CAIN
+25°C
65
E
125
VAOUT = ±10V, VAIN = ±10V
or floating
+25°C
-0.5
0.5
E
-20
20
VAIN = 0, f = 1MHz
+25°C
20
nA
pF
FAULT PROTECTION
Fault-Protected Analog Signal
Range (Notes 4, 6)
VAIN
Applies with power on
E
-36
36
Applies with power off
E
-40
40
+25°C
-20
E
-200
0.1
20
Input Signal-Path Leakage
Current, Supplies On
IAIN(ON)
VAIN = ±25V, VAOUT = open
Input Signal-Path Leakage
Current, Supplies Off
IAIN(OFF)
VAIN = ±40V, VAOUT = open
V+ = 0, V- = 0
+25°C
-20
E
-500
VAIN = 25V
+25°C
13
19
26
VAIN = -25V
+25°C
-26
-19
-13
Output Clamp Current,
Supplies On
IAOUT
Output Clamp Resistance,
Supplies On
RAOUT
±Fault Output Turn-On
Delay Time
2
IAOUT = 1mA
200
0.2
20
500
VAIN = 25V
+25°C
0.5
1.0
VAIN = -25V
+25°C
0.4
1.0
+25°C
10
RL = 10kΩ, VAIN = ±25V
_______________________________________________________________________________________
V
nA
nA
mA
kΩ
ns
Fault-Protected, High-Voltage,
Signal-Line Protector
MAX4505
ELECTRICAL CHARACTERISTICS—Dual Supplies (continued)
(V+ = +15V, V- = -15V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
±Fault Recovery Time
CONDITIONS
RL = 10kΩ, VAIN = ±25V
TA
MIN
+25°C
TYP
MAX
25
UNITS
µs
POWER SUPPLY
Power-Supply Range
V+, V-
E
I+
VAIN = 15V
I-
VAIN = 15V
Power-Supply Current
±8
+25°C
±18
45
E
240
+25°C
-150
E
-240
V
150
-45
µA
ELECTRICAL CHARACTERISTICS—Single Supply
(V+ = +12V, V- = 0, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
TA
MIN
E
0
TYP
MAX
UNITS
V+
V
200
Ω
ANALOG SWITCH
Fault-Free Analog Signal Range
(Note 4)
VAIN
VAIN = 12V
Analog Signal-Path Resistance
RON
VAIN = 10V, IAOUT = 1mA
Signal-Path Leakage Current
(Note 5)
IAOUT(ON)
+25°C
125
E
250
+25°C
-0.5
E
-20
20
Applies with power on
E
-36
36
Applies with power off
E
-40
40
VAIN = 10V or floating
0.05
0.5
nA
FAULT PROTECTION
Fault-Protected Analog Signal
Range (Notes 4, 6)
VAIN
Input Signal-Path Leakage
Current, Supply On (Note 7)
IAIN(ON)
VAIN = ±25V, VAOUT = 0
Input Signal-Path Leakage
Current, Supply Off (Note 7)
IAIN(OFF)
VAIN = ±40V
+25°C
-20
E
-200
+25°C
-20
E
-500
3
Output Clamp Current,
Supply On
IAOUT
VAIN = 25V
+25°C
Output Clamp Resistance,
Supply On
RAOUT
VAIN = ±25V
±Fault Output Turn-On
Delay Time
±Fault Recovery Time
0.2
20
200
0.2
20
500
V
nA
nA
5.5
10
mA
+25°C
1.0
2.5
kΩ
RL = 10kΩ, VAIN = 25V
+25°C
10
ns
RL = 10kΩ, VAIN = 25V
+25°C
2.5
µs
POWER SUPPLY
Power-Supply Range
Power-Supply Current
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
V+, VI+
E
VAIN = 12V
+25°C
E
+9
+36
5
25
40
V
µA
The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column.
See Fault-Free Analog Signal Range vs. Supply Voltage graph in the Typical Operating Characteristics.
Leakage parameters are 100% tested at maximum rated hot temperature and guaranteed by correlation at TA = +25°C.
Guaranteed by design.
Guaranteed by testing with dual supplies.
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.
_______________________________________________________________________________________
3
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX4505 toc02
200
RON (Ω)
60
100
V+ = +20V
V+ = +18V
V- = -18V
50
-15
-10
-5
0
5
10
15
0
20
0
5
10
15
VOUT_ (V)
ON-RESISTANCE vs. OUTPUT VOLTAGE
AND TEMPERATURE (SINGLE SUPPLY)
25
30
-15
35
V+ = +15V
V- = -15V
VIN = ±2.5V
0.6
VIN = +25V
TA = -40°C TA = +25°C
TA = -55°C
10
0.4
5
VIN = -25V
4
6
8
12
-55 -40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
OUTPUT TRANSFER CHARACTERISTICS
(DUAL SUPPLIES)
OUTPUT TRANSFER CHARACTERISTICS
(SINGLE SUPPLY)
FAULT-FREE ANALOG SIGNAL RANGE
vs. SUPPLY VOLTAGE
5
INPUT VOLTAGE
LINEARLY SWEPT
BETWEEN -30V
AND +30V
-10
(V+ = +8V, V- = -8V)
(V+ = +10V, V- = -10V)
(V+ = +15V, V- = -15V)
(V+ = +18V, V- = -18V)
OUTPUT LOAD = 1MΩ
-15
-20
-30
-20
-10
0
10
INPUT VOLTAGE (V)
20
30
35
V+ = +36V
30
V+ = +25V
25
20
V+ = +15V
15
V+ = +12V
10
20
MAX4505 toc09
OUTPUT LOAD = 1MΩ
V- = 0
15
OUTPUT VOLTAGE (V)
(V+ = +10V, V- = -10V)
(V+ = +8V, V- = -8V)
40
MAX4505 toc08
(V+ = +18V, V- = -18V)
(V+ = +15V, V- = -15V)
OUTPUT CLAMP VOLTAGE (V)
MAX4505 toc07
TEMPERATURE (°C)
10
-5
-25
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
VOUT_ (V)
15
4
10
V- = -15V
-20
0
2
20
0
0
-5
-15
0.1
0
15
-10
0.2
50
0
10
V+ = +15V
15
0.5
0.3
5
20
IOUT (mA)
ROUT (kΩ)
TA = +70°C
0
25
TA = +85°C
100
-5
OUTPUT CLAMP CURRENT (SUPPLIES ON)
vs. TEMPERATURE
0.7
TA = +125°C
150
-10
VOUT_ (V)
OUTPUT CLAMP RESISTANCE
(SUPPLIES ON) vs. TEMPERATURE
MAX4505 toc04
V+ = +12V
V- = 0
200
20
V+ = +15V
V- = -15V
VOUT_ (V)
250
TA = -40°C
TA = -55°C
0
MAX4505 toc05
-20
TA = +25°C
20
V+ = +36V
0
TA = +70°C
60
40
V+ = +30V
20
TA = +125°C
TA = +85°C
80
150
100
40
RON (Ω)
120
V+ = +12V
V+ = +15V
V- = -15V
80
V- = 0
V+ = +9V
MAX4505 toc06
100
ON-RESISTANCE vs. OUTPUT VOLTAGE
AND TEMPERATURE (DUAL SUPPLIES)
RON (Ω)
120
RON (Ω)
V+ = +8V
V- = -8V
V+ = +10V
V- = -10V
250
MAX4505 toc01
140
ON-RESISTANCE vs. OUTPUT VOLTAGE
(SINGLE SUPPLY)
MAX4505 toc03
ON-RESISTANCE vs. OUTPUT VOLTAGE
(DUAL SUPPLIES)
OUTPUT CLAMP VOLTAGE (V)
MAX4505
Fault-Protected, High-Voltage,
Signal-Line Protector
10
5
0
-5
-10
V+ = +9V
5
-15
INPUT VOLTAGE LINEARLY SWEPT
BETWEEN 0 AND 36V
0
0
5
10
15
20
25
INPUT VOLTAGE (V)
30
35
-20
40
-20
-15
-10
-5
0
5
INPUT VOLTAGE (V)
_______________________________________________________________________________________
10
15
20
Fault-Protected, High-Voltage,
Signal-Line Protector
100n
100p
IOUT (V+ = +12V, V- = 0)
10p
IIN AT +25V (V+ = +15V, V- = -15V)
10n
1n
100p
1p
0.1p
IIN AT +25V (V+ = +12V, V - = 0)
10p
-30
-5
20
45
70
95
120 145
SUPPLY CURRENT vs. INPUT VOLTAGE
25
45
65
85 105 125
-20
MAX4505 toc16
-15
-10
-5
0
5
10
MAX4505 toc15
-15V
-40
-50
+15V
-60
OUT_
0
10V/div
V+ = +15V
V- = -15V
-100
0.01
15
IN_
10V/div
-90
-60
+15V
-30
-80
I-
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
FAULT-FREE SIGNAL PERFORMANCE
-70
-40
I-
FREQUENCY RESPONSE
-20
0
-20
TEMPERATURE (°C)
0
20
I+ SINGLE SUPPLY +12V
0
TEMPERATURE (°C)
-10
BANDWIDTH (dB)
SUPPLY CURRENT (µA)
40
5
10
MAX4505 toc13
I+
20
-80
-55 -35 -15
TEMPERATURE (°C)
60
40
-60
0.1p
-55
V+ = +15V
V- = -15V
I+
-40
1p
0.01p
60
SUPPLY CURRENT (µA)
IOUT (V+ = +15V, V- = -15V)
1n
LEAKAGE CURRENT (A)
LEAKAGE CURRENT (A)
10n
80
MAX4505 toc11
VOUT = ±10V
POWER SUPPLY CURRENT
vs. TEMPERATURE
1µ
MAX4505 toc10
100n
INPUT FAULT LEAKAGE CURRENT
(SUPPLIES ON)
MAX4505 toc12
FAULT-FREE OUTPUT LEAKAGE CURRENT
(SUPPLIES ON)
INPUT VOLTAGE (V)
0.1
-15V
1
10
100
5µs/div
1000
FREQUENCY (MHz)
FAULT-FREE RAIL-TO-RAIL SIGNAL HANDLING
WITH ±15V SUPPLIES
INPUT OVERVOLTAGE
vs. OUTPUT CLAMPING
FAULT RECOVERY
MAX4505 toc17
MAX4505 toc18
+25V
+16V
IN_
5V/div
IN_
0
+15V
-25V
0
0
OUT_
-15V
5µs/div
±25V OVERVOLTAGE INPUT WITH THE OUTPUT
CLAMPED AT ±15V
+15V
0
OUT_
5V/div
V+ = +15V
V- = -15V
0
5µs/div
_______________________________________________________________________________________
5
MAX4505
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
Fault-Protected, High-Voltage,
Signal-Line Protector
MAX4505
Pin Description
PIN
SOT
µMAX
1
3
2
3
NAME
FUNCTION
AIN
Analog Fault-Protected Input
8
V+
Positive Supply Voltage Input
1
AOUT
4
2, 5, 6, 7
N.C.
5
4
V-
-15V
-15V
Analog Signal Output
No Connection. Not internally connected.
Negative Supply Voltage Input
COMPARATOR
N3
N-CHANNEL
DRIVER
SENSE
SWITCH
-V(-15V)
CLAMP N2
N1
IN
OUT
CLAMP P2
P1
P3
SENSE
SWITCH
+15V
+15V
+V(+15V)
P-CHANNEL
DRIVER
COMPARATOR
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 onresistance 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.
Figure 1. Simplified Internal Structure
Normal Operation
_______________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
6
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).
_______________________________________________________________________________________
Fault-Protected, High-Voltage,
Signal-Line Protector
MAX4505
+3V
1
AO
A1 16
+5V 2
EN
-15V 3
V-
A2 15
GND
14
O
NEW COM
MAX4505
1
V-
V-
V+
V+
2
8 +15V
4
NO1 MAX4508 V+ 13 +15V
7
5
NO2
NO5 12
6
NO3
NO6 11
7
NO4
NO7 10
8
COM
NO8 9
MAX4505
3
AOUT
AIN
VIN
-15V 4
6
5
ROUT
Figure 4. Demultiplexer Application Using MAX4505
with MAX4508
Figure 2. Application Circuit
+3V
OV
1
2
3
-15V 4
AO
A1 16
EN
-5V 3
V-
A2 15
GND
14
8 +15V
4
NO1 MAX338
7
5
NO2
NO5 12
6
NO3
NO6 11
7
NO4
NO7 10
8
VOUT
NO8 9
MAX4505
+25V
1
+5V 2
6
5
V+ 13 +15V
Figure 3. Protecting a MAX338 with a MAX4505
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 (
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