MAX367CWN ,Signal-Line Circuit ProtectorsGeneral Description ________
MAX367EWN ,Signal-Line Circuit ProtectorsFeaturesThe MAX366 and MAX367 are multiple, two-terminal circuit' ±40V Overvoltage Protectionprotec ..
MAX367EWN ,Signal-Line Circuit ProtectorsApplicationsMAX367 available after January 1, 1995.* Dice are tested at T = +25°C only.Process Cont ..
MAX367EWN+ ,Signal Line Circuit Protector with Three Independent ProtectorsMAX366/MAX36719-0326; Rev 0; 12/94Signal-Line Circuit Protectors_______________
MAX3680EAI ,+3.3V / 622Mbps / SDH/SONET 1:8 Deserializer with TTL OutputsELECTRICAL CHARACTERISTICS(V = +3.0V to +3.6V, T = -40°C to +85°C, unless otherwise noted. Typical ..
MAX3680EAI ,+3.3V / 622Mbps / SDH/SONET 1:8 Deserializer with TTL OutputsApplications622Mbps SDH/SONET Transmission Systems________________Ordering Information622Mbps ATM/S ..
MAX7316AEE+T ,10-Port I/O Expander with LED Intensity Control, Interrupt, and Hot-Insertion ProtectionFeatures2The MAX7316 I C/SMBus™-compatible serial interfaced♦ 400kbps, 2-Wire Serial Interface, 5.5 ..
MAX7316ATE+ ,10-Port I/O Expander with LED Intensity Control, Interrupt, and Hot-Insertion ProtectionApplications0.047μFLCD Backlights Keypad BacklightsV+LED Status Indication RGB LED Drivers P0μCP1Re ..
MAX7317AEE+ ,10-Port SPI-Interfaced I/O Expander with Overvoltage and Hot-Insertion ProtectionFeaturesThe MAX7317 serial-interfaced peripheral provides ● Industry-Standard 4-Wire Interface Sim ..
MAX7317AEE+ ,10-Port SPI-Interfaced I/O Expander with Overvoltage and Hot-Insertion ProtectionElectrical Characteristics(Typical Operating Circuit, V+ = 2.25V to 3.6V, T = T to T , unless other ..
MAX7317AEE+T ,10-Port SPI-Interfaced I/O Expander with Overvoltage and Hot-Insertion ProtectionMAX7317 10-Port SPI-Interfaced I/O Expander with Overvoltage and Hot-Insertion Protection
MAX7317ATE+ ,10-Port SPI-Interfaced I/O Expander with Overvoltage and Hot-Insertion ProtectionGeneral Description Beneits and
MAX366CPA-MAX366CSA-MAX366ESA-MAX367CWN-MAX367EWN
Signal-Line Circuit Protectors
_______________General DescriptionThe MAX366 and MAX367 are multiple, two-terminal circuit
protectors. Placed in series with signal lines, each two-ter-
minal device guards sensitive circuit components against
voltages near and beyond the normal supply voltages.
These devices are used at interfaces where sensitive cir-
cuits are connected to the external world and could
encounter damaging voltages (up to 35V beyond the sup-
ply rails) during power-up, power-down, or fault conditions.
The MAX366 contains three independent protectors and
the MAX367 contains eight. They can protect analog sig-
nals using either unipolar (4.5V to 36V) or bipolar (±2.25V
to ±18V) power supplies. Each protector is symmetrical.
Input and output terminals may be freely interchanged.
These devices are voltage-sensitive MOSFET transistor
arrays that are normally on when power is applied and
normally open circuit when power is off. With ±10V sup-
plies, on-resistance is 100Ωmax and leakage is less than
1nA at +25°C.
When signal voltages exceed or are within approximately
1.5V of either power-supply voltage (including when
power is off), the two-terminal resistance increases dra-
matically, limiting fault current as well as output voltage to
sensitive circuits. The protected side of the switch main-
tains the correct polarity and clamps approximately 1.5V
below the supply rail. There are no “glitches” or polarity
reversals going into or coming out of a fault condition.
________________________ApplicationsProcess Control SystemsRedundant/Backup Systems
Hot-Insertion Boards/SystemsATE Equipment
Data-Acquisition SystemsSensitive Instruments
____________________________Features±40V Overvoltage ProtectionOpen Signal Paths with Power Off
100ΩSignal Paths with Power On1nA Max Path Leakage at +25°C44V Maximum Supply Voltage RatingAutomatic Protection; No Programming or
Controls
______________Ordering Information
MAX366/MAX367
Signal-Line Circuit Protectors
________________________________________________________________Maxim Integrated Products1
___________________________________________________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.19-0326; Rev 0; 12/94
Pin Configurations appear at end of data sheet.MAX367 available after January 1, 1995.
* Dice are tested at TA= +25°C only.
* Contact factory foravailability.
MAX366/MAX367
Signal-Line Circuit Protectors_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(V+ = +15V, V- = -15V, TA= TMINto TMAX, unless otherwise noted.)
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.
Note 1:Guaranteed, but not tested.
Note 2:See Typical Operating Characteristicscurves for fault-free analog signal range at various supply voltages.
V+ to V-......................................................................-0.3V, +44V
IN_, OUT_..................................................(V- + 44V), (V+ - 44V)
Continuous Current into Any Terminal..............................±30mA
Peak Current into Any Terminal
(pulsed at 1ms, 10% duty cycle)...................................±70mA
Continuous Power Dissipation (TA= +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW
8-Pin SO (derate 5.88mW/°C above +70°C).................471mW
8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW
18-Pin Plastic DIP (derate 11.11mW/°C above +70°C)...889mW
18-Pin Wide SO (derate 9.52mW/°C above +70°C).....762mW
18-Pin CERDIP (derate 10.53mW/°C above +70°C).....842mW
Operating Temperature Ranges
MAX36_C_ _........................................................0°C to +70°C
MAX36_E_ _......................................................-40°C to +85°C
MAX36_M_ _...................................................-55°C to +125°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX366/MAX367
Signal-Line Circuit Protectors
_______________________________________________________________________________________3TRANSFER CHARACTERISTICS
(BIPOLAR SUPPLIES)
MAX366/7-02
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V),
INPUT & OUTPUT CURRENT (-15-55
TRANSFER CHARACTERISTICS
(SINGLE SUPPLY)
MAX366/7-03
INPUT VOLTAGE (V)
VIN > (V+ - 35V)
OUTPUT VOLTAGE (V),
INPUT & OUTPUT CURRENT (105
1E+01
1E+02
1E+03
1E+04
1E+05
1E+06
1E+07
1E+08
PATH RESISTANCE vs. INPUT VOLTAGE
(BIPOLAR SUPPLIES)
MAX366/7-04
INPUT VOLTAGE (V)
PATH RESISTANCE (-10-5105
PATH RESISTANCE vs. INPUT VOLTAGE
(BIPOLAR SUPPLIES)
MAX366/7-05
INPUT VOLTAGE (V)
PATH RESISTANCE (
__________________________________________Typical Operating Characteristics
(V+ = +15V, V- = -15V, TA= +25°C, unless otherwise noted.)
MAX366/MAX367
Signal-Line Circuit Protectors_______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)(V+ = +15V, V- = -15V, TA= +25°C, unless otherwise noted.)
MAX366 FREQUENCY RESPONSE
MAX366-TOC9
FREQUENCY (Hz)
LOSS (dB)
-1010k100k1M10M100M100
PATH RESISTANCE vs. INPUT VOLTAGE
(SINGLE SUPPLY)
MAX366/7-06
INPUT VOLTAGE (V)
PATH RESISTANCE (110
10k
100k
10M
100M
PATH RESISTANCE vs. INPUT VOLTAGE
(SINGLE SUPPLY)
MAX366/7-07
INPUT VOLTAGE (V)
PATH RESISTANCE (
350
MAX366/MAX367
Signal-Line Circuit Protectors
_______________________________________________________________________________________5
___________Background InformationWhen a voltage outside the supply range is applied to
most integrated circuits, there is a strong possibility they
will be damaged or “latch up” (that is, fail to operate prop-
erly even after the offending voltage is removed). If an
IC’s input or output pin is supplied with a voltage when the
IC’s power is off, and power is subsequently applied, the
device may act as an SCR and destroy itself and/or other
circuitry. Such “faults” are commonly encountered in
modular control systems where power and signals to inter-
connected modules may be interrupted and re-estab-
lished at random. They can happen during production
testing, maintenance, start-up, or a power “brownout.”
The MAX366/MAX367 are designed to protect delicate
input and output circuitry from overvoltage faults up to
±40V (with or without power applied), in devices such as
op amps, analog-to-digital/digital-to-analog converters,
and voltage references. These circuit protectors automati-
cally limit signal voltages and currents to safe levels with-
out degrading normal signal performance, even in very
high-impedance circuits. They are powered by the power
supply of the protected circuit and inserted into the signal
lines. There are no control lines, programming pins, or
adjustments.
Unlike shunt diode networks, these devices are low-
impedance FETs that become high impedance during a
fault condition, so fault current and power dissipation are
extremely low. Equally important, leakage current during
normal and fault conditions is extremely low. In addition,
unlike most discrete networks, these parts protect circuits
both when power is off and during power transitions.
_______________Detailed Description
Internal ConstructionFigure 1 shows the simplified internal construction of
each protector inside the MAX366/MAX367. Each circuit
consists of two N-channel FETs and one P-channel FET.
All the FETs are enhancement types; that is, the N chan-
nels must have approximately 1.3V of positive gate volt-
age in order to conduct, and the P channel must have
approximately 2V of negative gate voltage in order to
conduct.
During normal operation, V+ is connected to a positive
potential and V- is connected to a negative potential.
Since their gates are tied to V+, transistors Q1 and Q3
conduct as long as their sources are at least 1.3V below
V+ (the N-channel gate threshold.) Transistor Q2’s gate
is tied to V-, so it conducts as long as its source is 2V or
more above V- (the P-channel gate threshold.)
As long as the signal is within these limits, all three tran-
sistors conduct and a low-resistance path is maintained
from the IN to OUT pin. (Note that, since the device is
symmetrical, IN and OUT pins can be interchanged.)
When the signal is beyond the gate threshold of either
Q2 or Q1/Q3, the path resistance rises dramatically.
When power is off, none of the transistors have gate
bias, so the circuit from IN to OUT is open.
Normal OperationIn normal operation, the protector is placed in series
with the signal line and the power supplies are con-
nected to V+ and V- (see Figure 2). V- is ground when
operating with a single supply. When power is applied,
each protector acts as a resistor in the signal path.
Any voltage source on the “input” side of the switch will
be conducted through the protector to the output. (Note
that, since the protector is symmetrical, IN and OUT
pins can be interchanged.)
If the output load is resistive, it will draw current, and a
voltage divider will be formed with the internal resistance
so the output voltage will be lower than the input voltage.
Since the internal resistance is typically less than 100Ω,
high-impedance loads will be relatively unaffected by the
presence of the protector. The protector’s path resis-
tance is a function of the supply voltage and the signal
voltage (see Typical Operating Characteristics).
Power OffWhen power is off (i.e., V+ = V- = 0V), the protector is a
virtual open circuit, and all voltages on each side are
isolated from each other up to ±40V. With ±40V applied
to the input pin, the output pin will be 0V, regardless of
its resistance to ground.
Fault ConditionsA fault condition exists when the voltage on either sig-
nal pin is within about 1.5V of either supply rail or
exceeds either supply rail. This definition is valid when
power is applied and when it is off, as well as during all
the states as power ramps up or down.
During a fault, the protector acts as a variable resistor,
conducting only enough to sustain the other side of the
switch within about 1.5V of the supply rail. This voltage
is known as the “fault knee voltage,” and is not symmet-
rical. It is approximately 1.3V down from the positive
supply (V+ pin) or approximately 2.0V up from the neg-
ative supply (V- pin). Each fault knee voltage varies
slightly with supply voltage, with output current, and
from device to device.
During a fault condition, all the fault current flows
from one signal pin through the protector and out
the other signal pin. No fault current flows through
either supply pin.(There will be a few pico-amps of
leakage current from each signal pin to each supply
pin, but this is independent of fault current.)
During the fault condition, enough current will flow to
maintain the output voltage at the fault knee voltage, so
the fault current is a function of the output resistance
and the supply voltage. The output voltage and cur-
rent have the same polarity as the fault.The maximum input fault voltage is 40V from the “oppo-
site-polarity supply rail.” This means the input can go
to ±35V with ±5V supplies or to ±25V with ±15V sup-
plies. The fault voltage is highest (±40V) when the sup-
plies are off (V+ = V- = 0V).
Using the circuit of Figure 2, the approximate fault cur-
rents are as follows:
1) For positive faults:
I(F)≈(V+ - 1.3V - VLOW) ÷ROUT
2) For negative faults:
I(F)≈(V- + 2V + VLOW) ÷ROUT
where VLOWis the terminating voltage at the far end of
ROUT. VLOW= 0V when ROUTis grounded.
MAX366/MAX367
Signal-Line Circuit Protectors_______________________________________________________________________________________
