MAX4511ESE+T ,Quad, Rail-to-Rail, Fault-Protected, SPST Analog SwitchesApplicationsATE Equipment Avionics1IN1 16IN2 Data Acquisition Redundant/BackupCOM1 2 15 COM2Systems ..
MAX4512CSE ,Quad, Rail-to-Rail, Fault-Protected, SPST Analog SwitchesApplicationsATE Equipment IN1 1 16IN2 Data AcquisitionCOM1 2 15 COM2Industrial and Process-Control ..
MAX4512CSE+ ,Quad, Rail-to-Rail, Fault-Protected, SPST Analog SwitchesFeaturesThe MAX4511/MAX4512/MAX4513 are quad, single-♦ ±40V Fault Protection with Power Offpole/sin ..
MAX4512ESE ,Quad, Rail-to-Rail, Fault-Protected, SPST Analog SwitchesFeaturesThe MAX4511/MAX4512/MAX4513 are quad, single-' ±40V Fault Protection with Power Offpole/sin ..
MAX4512ESE+ ,Quad, Rail-to-Rail, Fault-Protected, SPST Analog SwitchesELECTRICAL CHARACTERISTICS—Dual SuppliesV+ = +15V, V- = -15V, GND = 0V, T =T to T , unless otherwis ..
MAX4513ESE ,Quad, Rail-to-Rail, Fault-Protected, SPST Analog SwitchesApplicationsATE Equipment IN1 1 16IN2 Data AcquisitionCOM1 2 15 COM2Industrial and Process-Control ..
MAX8544EEP+ ,Step-Down Controllers with Prebias Startup, Lossless Sensing, Synchronization, and OVPApplications Ordering InformationBase Stations PART TEMP RANGE PIN-PACKAGE Networks and TelecomMAX8 ..
MAX8545EUB ,Low-Cost / Wide Input Range / Step-Down Controllers with Foldback Current Limitapplications. No Additional Bias Supply NeededThey drive low-cost N-channel MOSFETs for both thehi ..
MAX8545EUB+T ,Low-Cost, Wide Input Range, Step-Down Controllers with Foldback Current LimitMAX8545/MAX8546/MAX854819-2795; Rev 2; 6/07Low-Cost, Wide Input Range, Step-DownControllers with Fo ..
MAX8546EUB ,Low-Cost / Wide Input Range / Step-Down Controllers with Foldback Current Limitapplications. It drives low-cost N-channel MOSFETs for both the high-side switch and synchronous re ..
MAX8546EUB ,Low-Cost / Wide Input Range / Step-Down Controllers with Foldback Current Limit MAX8546EUB Rev. A RELIABILITY REPORT FOR MAX8546EUB PLASTIC ENCA ..
MAX8546EUB ,Low-Cost / Wide Input Range / Step-Down Controllers with Foldback Current LimitTable of Contents I. ........Device Description V. ........Quality Assurance Information II ..
MAX4511CPE+-MAX4511CSE+-MAX4511ESE+-MAX4511ESE+T-MAX4512CSE+-MAX4512ESE+-MAX4513ESE+
Quad, Rail-to-Rail, Fault-Protected, SPST Analog Switches
General DescriptionThe MAX4511/MAX4512/MAX4513 are quad, single-
pole/single-throw (SPST), fault-protected analog switch-
es. They are pin-compatible with the industry-standard
nonprotected DG201/DG202/DG213. These new switch-
es feature fault-protected inputs and Rail-to-Rail®signal
handling capability. The normally open (NO_) and
normally closed (NC_) terminals are protected from
overvoltage faults up to 36V during power-up or
power-down. During a fault condition, the NO_ or NC_
terminal becomes an open circuit and only nanoamperes
of leakage current flow from the source, but the switch
output (COM_) furnishes up to 10mA of the appropriate
polarity supply voltage to the load. This ensures unam-
biguous rail-to-rail outputs when a fault begins and ends.
On-resistance is 175Ωmax and is matched between
switches to 10Ωmax. The off-leakage current is only
0.5nA at +25°C and 10nA at +85°C.
The MAX4511 has four normally closed switches. The
MAX4512 has four normally open switches. The
MAX4513 has two normally closed and two normally
open switches.
These CMOS switches can operate with dual power
supplies ranging from ±4.5V to ±18V or a single supply
between +9V and +36V.
All digital inputs have +0.8V and +2.4V logic thresh-
olds, ensuring both TTL- and CMOS-logic compatibility
when using ±15V or a single +12V supply.
Applications
Features±40V Fault Protection with Power Off
±36V Fault Protection with ±15V SuppliesAll Switches Off with Power OffRail-to-Rail Signal HandlingOutput Clamped to Appropriate Supply Voltage
During Fault Condition; No Transition Glitch175Ωmax Signal Paths with ±15V SuppliesNo Power-Supply Sequencing Required±4.5V to ±18V Dual Supplies
+9V to +36V Single SupplyLow Power Consumption, <2mW Four Separately Controlled SPST SwitchesPin-Compatible with Industry-Standard
DG411/DG412/DG413, DG201/DG202/DG213TTL- and CMOS-Compatible Logic Inputs with
Single +9V to +15V or ±15V Supplies
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog SwitchesTOP VIEW
DIP/SO/TSSOP
MAX4511
LOGICSWITCHOFF
IN2
COM2
NC2V-
NC1
COM1
IN1
MAX4511N.C.
NC3
COM3
IN3IN4
COM4
NC4
GND
N.C. = NOT CONNECTED
SWITCHES SHOWN FOR LOGIC "0" INPUT.
ALL SWITCHES ARE OFF WITH POWER REMOVED.
19-4760; Rev 1; 8/02
Ordering Information continued at end of data sheet.*Contact factory for dice specifications.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
Ordering Information
PARTTEMP RANGEPIN-PACKAGEMAX4511C/D0°C to +70°CDice*
MAX4511CPE0°C to +70°C16 Plastic DIP
MAX4511CSE0°C to +70°C16 Narrow SO
Continued at end of data sheet.
MAX4511EPE-40°C to +85°C16 Plastic DIP
MAX4511MJE-55°C to +125°C16 CERDIP
MAX4511ESE-40°C to +85°C16 Narrow SO
Pin Configurations/
Functional Diagrams/Truth TablesATE Equipment
Data Acquisition
Industrial and Process-
Control Systems
Avionics
Redundant/Backup
Systems
MAX4511CUE0°C to +70°C16 TSSOP
MAX4511EUE-40°C to +85°C16 TSSOP
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS—Dual Supplies(V+ = +15V, V- = -15V, GND = 0V, TA =TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
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:COM_ and IN_ pins are not fault protected. Signals on COM_ or IN_ exceeding V+ or V- are clamped by internal diodes.
Limit forward diode current to maximum current rating.
Note 2:NC_ and NO_ pins are fault protected. Signals on NC_ or NO_ exceeding -36V to +36V may damage the device. These
limits apply with power applied to V+ or V-, or ±40V with V+ = V- = 0.
(Voltages Referenced to GND)........................................................................-0.3V to +44.0V
V-.........................................................................-44.0V to +0.3V
V+ to V-................................................................-0.3V to +44.0V
COM_, IN_ (Note 1)..............................(V- - 0.3V) to (V+ + 0.3V)
NC_, NO_ (Note 2)..................................(V+ - 36V) to (V- + 36V)
NC_, NO_ to COM_.................................................-36V to +36V
Continuous Current into Any Terminal..............................±30mA
Peak Current into Any Terminal
(pulsed at 1ms, 10% duty cycle)...................................±50mA
Continuous Power Dissipation (TA= +70°C) (Note 2)
Plastic DIP (derate 10.53mW/°C above +70°C)...........842mW
Narrow SO (derate 8.70mW/°C above +70°C).............696mW
TSSOP (derate 9.4mW/°C above +70°C)..................754.7mW
CERDIP (derate 10.00mW/°C above +70°C)................800mW
Operating Temperature Ranges
MAX451_C_ E......................................................0°C to +70°C
MAX451_E_ E...................................................-40°C to +85°C
MAX451_MJE.................................................-55°C to +125°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
Applies with power on or off
(Note 2)
VCOM_= ±14V;
VNO_,VCOM = 14V
VCOM_= ±10V, ICOM_= 1mA
VCOM_= ±10V, ICOM_= 1mA
CONDITIONSC, E, M
-2020ICOM_(OFF)
-0.50.010.5-3636VNO_, VNC_Fault-Protected Analog
Signal Range
ΔRON
COM_ -NO_ or COM_ -NC_
On-Resistance Match Between
Channels (Note 4)
RONCOM_ -NO_ or COM_ -NC_
On-Resistance
UNITSMINTYPMAX(Note 3)
SYMBOLPARAMETERC, E
+25°C
+25°C
+25°C
Applies with power on or off
(Note 2)C, E, MVV-V+VNO_, VNC_Fault-Free Analog Signal RangeM
Applies with power on or off
(Note 1)C, E, MVV- - 0.3V+ + 0.3VCOM_Non-Protected Analog
Signal Range (COM_ Output)
ANALOG SWITCH200C, E
C, E10
COM_ Off Leakage Current
(Note 5)
VCOM_= ±14V;
VNO_,VCOM = 14V
NO_ or NC_Off LeakageCurrent
(Note 5)nAINO_(OFF),
INC_(OFF)
-0.50.010.5+25°C
-1010C, E
-200200M
-1010C, E
-200200M
VCOM_= ±14VnAICOM_(ON)COM_ On Leakage Current
(Note 5)
-0.50.010.5+25°C
-400400M
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
ELECTRICAL CHARACTERISTICS—Dual Supplies (continued)(V+ = +15V, V- = -15V, GND = 0V, TA =TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
VNO_or VNC_ = ±33V
VNO_or VNC_ = ±33V
CONDITIONS+25°C
tONTurn-On Time600RCOM_COM_ On Output Resistance,
Supplies On2.5-1010
ICOM_COM_ Output Leakage Current,
Supplies On
UNITSMINTYPMAX(Note 3)
SYMBOLPARAMETER+25°C
+25°C
VNO_or VNC_ = 33VmAICOM_COM_ On Output Current,
Supplies On
81113+25°C
VNO_or VNC_ = ±40V,
V+ = 0, V- = 0-1010
INO_, INC_NO_ or NC_ Input Leakage
Current, Supplies Off-200200
+25°C-11µA
1.92.4VVIN_HIN_ Input Logic Threshold HighC, E, M
900M
VCOM_= ±10V, RL_= 2kΩ,
Figure 3nstBBMBreak-Before-Make Time
Delay (MAX4513 Only)50100+25°C0.031VIN_ = 0.8V or 2.4VµAIINH_, IINLIN_ Input Current Logic High
or Low
+25°C
C, E-200200
C, E
VNO_or VNC_ = -33V-12-10-7
C, E, M
C, E, M-55
C, E
VCOM_= ±10V, RL_= 2kΩ,
Figure 2ns
tOFFTurn-Off Time500C, E
750M
200400VCOM_= ±10V, RL_= 2kΩ,
Figure 2ns
+25°C
VNO_or VNC_ = ±25V,
VCOM_= 10V -1010
INO_, INC_NO_ or NC_ Off Input Leakage
Current, Supplies On-200200
+25°C
C, E
SWITCH DYNAMICCHARAC-= 1.0nF, VNO_= 0,
RS = 0Ω, Figure 4pCQCharge Injection (Note 6)1.55+25°C
f = 1MHz, Figure 5pFCN_(OFF)NO_ or NC_ Off-Capacitance10+25°C
f = 1MHz, Figure 5pFCCOM_(OFF)COM_ Off-Capacitance5+25°C
f = 1MHz, Figure 5pFCCOM_(ON)COM_ On-Capacitance10+25°C
LOGIC INPUT= 50Ω, CL= 15pF,
VN_= 1VRMS, f = 1MHz, Figure 6dBVCISOOff Isolation (Note 7)-62+25°C= 50Ω, CL= 15pF,
VN_= 1VRMS, f = 1MHz, Figure 6dBVCTChannel-to-Channel Crosstalk
(Note 9)-66+25°C
0.81.9VVIN_LIN_ Input Logic Threshold LowC, E, M
FAULT(V+ = +15V, V- = -15V, unless otherwise noted.)
LOGIC INPUT
SWITCH DYNAMIC CHARACTERISTICS
All VIN_= 0 or 15V
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
ELECTRICAL CHARACTERISTICS—Dual Supplies (continued)(V+ = +15V, V- = -15V, GND = 0V, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
CONDITIONSUNITSMINTYPMAX(Note 3)
SYMBOLPARAMETERTAPower-Supply RangeV+, V-C,E, M±4.5±18V
V+ Supply CurrentI+All VIN_= 0 or 5V+25°C280400µA
V- Supply CurrentI-All VIN_= 0 or 5V+25°C90200µA
GND Supply CurrentIGND
All VIN_= 0 or 15V+25°C-10.011µA
600C, E, M
C, E, M300
C, E, M10
+25°C150250µAC, E, M450All VIN_= 5V
POWER SUPPLY
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
ELECTRICAL CHARACTERISTICS—Single +12V Supply(V+ = +10.8V to +13.2V, V- = 0, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
Applies with power on or off
(Note 2)C, E, MV
Applies with power on or off
(Note 2)
0V+VNO_, VNC_Fault-Free Analog Signal Range
V+ = 12V; VCOM _= 0;
VNO_, VNC_ = 12V
V+ = 12V, VCOM_= 10V,
ICOM_= 1mA
V+ = 12V, VCOM_= 10V,
ICOM_= 1mA
CONDITIONSC, E, M
Applies with power on or off
(Note 1)C, E, MV-0.3V+ + 0.3VCOM_Non-Protected Analog
Signal Range (COM_ Output)
V+ = 12V; VCOM_= 10V;
VNO_, VNC = 0 or 12VnA
ION_(OFF),
INC_(OFF)M
NO_ or NC_ Off Leakage Current
(Notes 5, 9)
-0.50.010.5+25°CICOM_(OFF)COM_ Off Leakage Current
(Notes 5, 9)
-0.50.010.5-3636VNO_, VNC_Fault-Protected Analog
Signal Range
ΔRON
COM_ -NO_ or COM_ -NC_
On-Resistance Match Between
Channels (Note 4)
RONCOM_ -NO_ or COM_ -NC_
On-Resistance
UNITSMINTYPMAX(Note 3)
SYMBOLPARAMETER+25°C
C, E
C, E
+25°C
+25°C410
-1010C, E-200200
-1010C, E
-200200M
V+ = 12V,
VCOM_= 10V or 12V-2020C, EnAICOM_(ON)COM_ On Leakage Current
(Notes 5, 9)
-400400M
-0.50.010.5+25°C
VNO_or VNC_ = ±25V,
VCOM_= 0, V+ = 12V-200200C, EnAINO_, INC_NO_ or NC_ Off Input Leakage
Current, Supply On-1010M
-2020+25°C
VNO_or VNC_ = ±40V,
V+ = 0, V- = 0-200200C, EnAINO_, INC_NO_ or NC_ Input Leakage
Current, Supply Off
-1010M
-200.120+25°C
VNO_or VNC_ = 25V,
V+ = 12V235mAICOM_COM_ Output Current,
Supply On+25°C
VNO_or VNC_ = 10V
V+ = 12VkΩRCOM_COM_ Output Resistance,
Supply On2.45+25°C
VNO_or VNC_ = ±30V,
V+ = 12V-200200C, EnAICOM_COM_ Output Leakage
Current, Supply On-11M
-1010+25°C
FAULT
ANALOG SWITCH
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
Note 1:COM_ and IN_ pins are not fault protected. Signals on COM_ or IN_ exceeding V+ or V- are clamped by internal diodes.
Limit forward diode current to maximum current rating.
Note 2:NC_ and NO_ pins are fault protected. Signals on NC_ or NO_ exceeding -36V to +36V may damage the device. These
limits apply with power applied to V+ or V-, or ±40V with V+ = V- = 0.
Note 3:The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column.
Note 4:ΔRON= ΔRON(MAX)- ΔRON(MIN).
Note 5:Leakage parameters are 100% tested at maximum rated hot temperature and guaranteed by correlation at TA= +25°C.
Note 6:Guaranteed by design.
Note 7:Off isolation = 20 log10 [ VCOM_/ (VNC_or VNO_) ], VCOM_= output, VNC_or VNO_= input to off switch.
Note 8:Between any two switches.
Note 9:Leakage testing for single-supply operation is guaranteed by testing with dual supplies.
ELECTRICAL CHARACTERISTICS—Single +12V Supply (continued)(V+ = +10.8V to +13.2V, V- = 0, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
VCOM_= 10V, RL_= 2kΩ,
Figure 2
CONDITIONSVCOM_= 10V, RL_= 2kΩ,
Figure 3tONTurn-On Time
5001000VIN_HIN_ Input Logic Threshold HighC, E, M
0.81.8VVIN_LIN_ Input Logic Threshold LowC, E, M
VCOM_= 10V, RL_= 2kΩ,
Figure 2ns0.031
tOFFTurn-Off Time400900
+25°C
tBBMBreak-Before-Make Time
Delay (MAX4513 Only)50100+25°C
VIN_ = 0.8V or 2.4VµAIIN_H, IIN_L
UNITSMINTYPMAX(Note 3)
SYMBOLPARAMETERIN_ Input Current Logic High
or Low
+25°C
+25°C
LOGIC INPUTC, E, M-55
C, E, M
C, E, M1500
1200= 1.0nF, VNO_= 0, = 0Ω, Figure 4pCQCharge Injection (Note 6)15+25°C
f = 1MHz, Figure 5pFCN_ (OFF)NO_ or NC_ Off Capacitance9+25°C
VCOM_= GND, f = 1MHz,
Figure 5pFCCOM_ (OFF)COM_ Off Capacitance9+25°C
VCOM_= VNO_= GND,
f = 1MHz, Figure 5pFCCOM_ (ON)COM_ On Capacitance22+25°C= 50Ω, CL= 15pF,
VN_= 1VRMS, f = 1MHz, Figure 6dBVISOOff Isolation (Note 7)-62+25°C= 50Ω, CL= 15pF,
VN_= 1VRMS, f = 1MHz, Figure 5dBVCTChannel-to-Channel Crosstalk
(Note 8)-65+25°CV+Power-Supply Range936C,E, M
All VIN_= 0 or 5VµAI+V+ Supply Current150300+25°C
All VIN_= 0 or 12V
IGNDV- and GND Supply Current100+25°C
All VIN_= 5V150300+25°C
450C, E, M
C, E, M
C, E, M
SWITCH DYNAMICCHARACTERISTICS
POWER SUPPLY
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
__________________________________________Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
SWITCH ON-RESISTANCE
vs. VCOM (DUAL SUPPLIES)
MAX4511-01
VCOM (V)
SWITCH ON-RESISTANCE (
V+ = +5V
V- = -5V
V+ = +10V
V- = -10V
V+ = +15V
V- = -15V
V+ = +12V
V- = -12V
V+ = +20V
V- = -20V
SWITCH ON-RESISTANCE vs. VCOM AND
TEMPERATURE (DUAL SUPPLIES)
MAX4511-02
VCOM (V)
SWITCH ON-RESISTANCE (
TA = +125°C
TA = -55°C
V+ = +15V
V- = -15V
TA = -40°C
TA = +25°C
TA = +85°C
SWITCH ON-RESISTANCE
vs. VCOM (SINGLE SUPPLY)
MA4511-03
VCOM (V)
SWITCH ON-RESISITANCE (
V+ = +12V
V+ = +5VV- = 0
V+ = +15V
V+ = +20V
V+ = +24V
V+ = +30V
SWITCH ON-RESISTANCE vs. VCOM
AND TEMPERATURE (SINGLE SUPPLY)
MAX4511-04
VCOM (V)
SWITCH ON-RESISTANCE (
TA = +125°CTA = +85°C
TA = +25°CTA = -40°C
TA = -55°C
V+ = +12V
ON AND OFF TIMES
vs. SUPPLY VOLTAGE
MAX4511-07
SUPPLY VOLTAGE (±V)
tON
, t
OFF
(ns)
tON
(SINGLE SUPPLY)
tON
(DUAL SUPPLIES)
tOFF
(DUAL SUPPLIES)
tOFF
(SINGLE
SUPPLY)
10p
100p
10n
100n
ID(ON), IS(OFF), AND ID(OFF)
LEAKAGES vs. TEMPERATURE
MAX4511-05
TEMPERATURE (°C)
LEAKAGE (A)
INO(OFF) @VNO = -14V,
VCOM = +14V
ICOM(ON) @VNO
= VCOM = +14V
INO(OFF) @VNO = +14V,
VCOM = -14V
ICOM(OFF) @VNO = -14V,
VCOM = +14V
ICOM(OFF) @VNO = +14V,
VCOM = -14V
ICOM(ON) @VNO
= VCOM = -14V
CHARGE INJECTION
vs. VCOM (DUAL SUPPLIES)
MAX4511-06
VCOM (V)
Q (pC)
DUAL ±15V
SUPPLIES
SINGLE +12V
SUPPLY
V+ = +15V
V- = -15V
ON AND OFF TIMES
vs. TEMPERATURE
MAX4511-08
TEMPERATURE (°C)
tON
, t
OFF
(ns)
tON
tOFF
POWER-SUPPLY CURRENT
vs. TEMPERATURE
MAX4511-09
TEMPERATURE (°C)
SUPPLY CURRENT
(μ
IV+
IV-
IGND
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog SwitchesLOGIC-LEVEL THRESHOLD vs. V+
MAX4511-10
V+ (V)
LOGIC-LEVEL THRESHOLD (V)
Typical Operating Characteristics (continued)(TA= +25°C, unless otherwise noted.)
FREQUENCY RESPONSE
MAX186-14A
FREQUENCY (MHz)
LOSS (dB)
PHASE (DEGREES)
ON LOSS
OFF LOSS
ON PHASE
NAMEFUNCTION1, 16,
9, 8IN1–IN4Logic Control Digital Inputs
2, 15,
10, 7
COM1–
COM4Analog Switch Common* Terminals
PIN3, 14,
11, 6
NO1–NO4orNC1–NC4
Analog Switch Fault-Protected Normally
Open* or Normally Closed* TerminalsV-Negative Analog Supply Voltage Input.
Connect to GND for single-supply operation.V+Positive Analog and Digital Supply-Voltage
Input. Internally connected to substrate.N.C.No Connection—not internally connectedGNDGround. Connect to digital ground. (Analog
signals have no ground reference.)
Pin Description*As long as the voltage on NO_ or NC_ does not exceed V+ or
V-, NO_ (or NC_) and COM_ pins are identical and interchange-
able. Either may be considered as an input or output; signals
pass equally well in either direction.
Detailed Description
Overview of Traditional
Fault-Protected SwitchesThe MAX4511/MAX4512/MAX4513 are fault-protected
CMOS analog switches with unusual operation and
construction. Traditional fault-protected switches are
constructed by three series FETs. This produces good
off characteristics, but fairly high on-resistance when
the signals are within about 3V of each supply rail. As
the voltage on one side of the switch approaches with-
in about 3V of either supply rail (a fault condition), the
switch impedance becomes higher, limiting the output
signal range (on the protected side of the switch) to
approximately 3V less than the appropriate polarity
supply voltage.
During a fault condition, the output current that flows
from the protected side of the switch into its load
comes from the fault source on the other side of the
switch. If the switch is open or the load is extremely
high impedance, the input current will be very low. If
the switch is on and the load is low impedance,
enough current will flow from the source to maintain the
load voltage at 3V less than the supply.
MAX451
/MAX451
/MAX451
Quad, Rail-to-Rail, Fault-Protected,
SPST Analog Switches
Overview of MAX4511/MAX4512/MAX4513The MAX4511/MAX4512/MAX4513 differ considerably
from traditional fault-protection switches, with several
advantages. First, they are constructed with two paral-
lel FETs, allowing very low on-resistance when the
switch is on. Second, they allow signals on the NC_ or
NO_ pins that are within or slightly beyond the supply
rails to be passed through the switch to the COM termi-
nal, allowing rail-to-rail signal operation. Third, when a
signal on NC_ or NO_ exceeds the supply rails by
about 50mV (a fault condition), the voltage on COM_ is
limited to the appropriate polarity supply voltage.
Operation is identical for both fault polarities. The fault-
protection extends to ±36V from GND.
During a fault condition, the NO_ or NC_ input pin
becomes high impedance regardless of the switch
state or load resistance. If the switch is on, the COM_
output current is furnished from the V+ or V- pin by
“booster” FETs connected to each supply pin. These
FETs can typically source or sink up to 10mA.
When power is removed, the fault protection is still in
effect. In this case, the NO_ or NC_ terminals are a vir-
tual open circuit. The fault can be up to ±40V.
The COM_ pins are not fault protected; they act as nor-
mal CMOS switch pins. If a voltage source is connect-
ed to any COM_ pin, it should be limited to the supply
voltages. Exceeding the supply voltage will cause high
currents to flow through the ESD protection diodes,
possibly damaging the device (see Absolute Maximum
Ratings).
Pin CompatibilityThese switches have identical pinouts to common non-
fault-protected CMOS switches. Care should be exer-
cised in considering them for direct replacements in
existing printed circuit boards, however, since only the
NO_ and NC_ pins of each switch are fault protected.
Internal ConstructionInternal construction is shown in Figure 1, with the ana-
log signal paths shown in bold. A single normally open
NO_
(NC_)
IN_
GND
HIGH
FAULT
LOW
FAULT
COM_
NC SWITCH
-ESD DIODE
NORMALLY OPEN SWITCH CONSTRUCTIONFigure 1. Block Diagram
