19-1902; Rev 1; 8/94
High-Voltage, Fault-Protected
Analog Multiplexers
_______________General Description
The MAX378 8-channel single-ended (1-of-8) multiplexer
and the MAX379 4-channel differential (2-of-8) multiplexer
use a series N-channel/P-channel/N-channel structure to
provide significant fault protection. If the power supplies to
the MAX378/MAX379 are inadvertently turned off while
input voltages are still applied,
all
channels in the muxes
are turned off, and only a few nanoamperes of leakage cur-
rent will flow into the inputs. This protects not only the
MAX378/MAX379 and the circuitry they drive, but also the
sensors or signal sources that drive the muxes.
The series N-channel/P-channel/N-channel protection
structure has two significant advantages over the simple
current-limiting protection scheme of the industry’s first-
generation fault-protected muxes. First, the Maxim protec-
tion scheme limits fault currents to nanoamp leakage
values rather than many milliamperes. This prevents dam-
age to sensors or other sensitive signal sources. Second,
the MAX378/MAX379 fault-protected muxes can withstand
a
continuous
±60V input, unlike the first generation, which
had a continuous ±35V input limitation imposed by power
dissipation considerations.
All digital inputs have logic thresholds of 0.8V and 2.4V,
ensuring both TTL and CMOS compatibility without requir-
ing pull-up resistors. Break-before-make operation is
guaranteed. Power dissipation is less than 2mW.
____________________________Features
o
Fault Input Voltage ±75V with Power Supplies Off
o
Fault Input Voltage ±60V with ±15V Power Supplies
o
All Switches Off with Power Supplies Off
o
On Channel Turns OFF if Overvoltage Occurs on
Input or Output
o
Only Nanoamperes of Input Current Under All
Fault Conditions
o
No Increase in Supply Currents Due to Fault
Conditions
o
Latchup-Proof Construction
o
Operates from ±4.5V to ±18V Supplies
o
All Digital Inputs are TTL and CMOS Compatible
o
Low-Power Monolithic CMOS Design
MAX378/MAX379
______________Ordering Information
PART
MAX378CPE
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
16 Plastic DIP
________________________Applications
Data Acquisition Systems
Industrial and Process Control Systems
Avionics Test Equipment
Signal Routing Between Systems
MAX378CWG
0°C to +70°C
24 Wide SO
MAX378CJE
0°C to +70°C
16 CERDIP
MAX378C/D
0°C to +70°C
Dice**
MAX378EPE
-40°C to +85°C
16 Plastic DIP
MAX378EWG
-40°C to +85°C
24 Wide SO
MAX378EJE
-40°C to +85°C
16 CERDIP
MAX378MJE
-55°C to +125°C
16 CERDIP
MAX378MLP
-55°C to +125°C
20 LCC*
Ordering Information continued at end of data sheet.
* Contact factory for availability.
**The substrate may be allowed to float or be tied to V+ (JI CMOS).
__________________________________________________________Pin Configurations
TOP VIEW
A0 1
EN 2
V- 3
IN1 4
IN2 5
IN3 6
IN4 7
OUT 8
16 A1
15 A2
14 GND
A0 1
EN 2
V- 3
IN1A 4
IN2A 5
IN3A 6
IN4A 7
OUTA 8
16 A1
15 GND
14 V+
MAX378
13 V+
12 IN5
11 IN6
10 IN7
9
IN8
MAX379
13 IN1B
12 IN2B
11 IN3B
10 IN4B
9
OUTB
DIP
Pin Configurations continued at end of data sheet.
DIP
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
High-Voltage, Fault-Protected
Analog Multiplexers
MAX378/MAX379
ABSOLUTE MAXIMUM RATINGS
Voltage between Supply Pins ..............................................+44V
V+ to Ground ...................................................................+22V
V- to Ground......................................................................-22V
Digital Input Overvoltage:
V+......................................................................+4V
V
EN
, V
A
V- ........................................................................-4V
Analog Input with Multiplexer Power On..............................±65V
Recommended
V+ .....................................+15V
Power Supplies
V- .......................................-15V
Analog Input with Multiplexer Power Off..............................±80V
Continuous Current, IN or OUT...........................................20mA
Peak Current, IN or OUT
(Pulsed at 1ms, 10% duty cycle max) ............................40mA
Power Dissipation (Note 1) (CERDIP) ................................1.28W
Operating Temperature Range:
MAX378/379C .....................................................0°C to +70°C
MAX378/379E ..................................................-40°C to +85°C
MAX378/379M ...............................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Note 1:
Derate 12.8mW/°C above T
A
= +75°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.
ELECTRICAL CHARACTERISTICS
(V+ = +15V, V- = -15V; V
AH
(Logic Level High) = +2.4V, V
AL
(Logic Level Low) = +0.8V, unless otherwise noted.)
-55°C to +125°C
MIN TYP MAX
STATIC
ON Resistance
OFF Input Leakage Current
r
DS(ON)
I
IN(OFF)
V
OUT
= ±10V, I
IN
= 100µA
V
AL
= 0.8V, V
AH
= 2.4V
V
IN
= ±10V, V
OUT
=
V
EN
= 0.8V (Note 6)
V
OUT
= ±10V, V
IN
=
V
EN
= 0.8V
(Note 6)
±
10V
+25°C
Full
+25°C
Full
10V
MAX378
MAX379
+25°C
Full
Full
+25°C
Full
Full
Full
Full
±
-50
-1.0
-200
-100
-10
-600
-300
-15
-50
0.1
0.1
2.0
3.0
-0.5 0.03
3.0
4.0
0.5
50
1.0
200
100
10
600
300
+15
50
-50
-2.0
-200
-100
-20
-600
-300
-15
-50
0.1
0.1
2.0
3.0
-1.0 0.03
3.5
4.0
1.0
50
2.0
200
100
20
600
300
+15
50
V
nA
nA
nA
kΩ
nA
0°C to +70°C
and
-40°C to +85°C
MIN TYP MAX
PARAMETER
SYMBOL
CONDITIONS
TEMP
UNITS
OFF Output Leakage Current
I
OUT(OFF)
ON Channel Leakage Current
Analog Signal Range
Differential OFF Output
Leakage Current
FAULT
Output Leakage Current
(with Input Overvoltage)
Input Leakage Current
(with Overvoltage)
Input Leakage Current
(with Power Supplies Off)
CONTROL
Input Low Threshold
Input High Threshold
Input Leakage Current
(High or Low)
2
I
OUT(ON)
V
AN
I
DIFF
V
IN(ALL)
= V
OUT
= ±10V
V
AH
= V
EN
= 2.4V
MAX378
V
AL
= 0.8V (Note 5)
MAX379
(Note 2)
MAX379 only
(Note 6)
I
OUT(OFF)
I
IN(OFF)
I
IN(OFF)
V
OUT
= 0V, V
IN
= ±60V
(Notes 3, 4)
V
IN
= ±60V, V
OUT
= ±10V
(Notes 3, 4)
V
IN
= ±75V, V
EN
= V
OUT
= 0V
A
0
= A
1
= A
2
= 0V or 5V
(Note 4)
(Note 4)
V
A
= 5V or 0V (Note 5)
+25°C
Full
+25°C
+25°C
20
10
25
10
20
20
40
20
nA
µA
µA
µA
V
AL
V
AH
I
A
Full
Full
Full
2.4
-1.0
0.8
2.4
1.0
-1.0
0.8
V
V
1.0
µA
_______________________________________________________________________________________
High-Voltage, Fault-Protected
Analog Multiplexers
ELECTRICAL CHARACTERISTICS (continued)
(V+ = +15V, V- = -15V; V
AH
(Logic Level High) = +2.4V, V
AL
(Logic Level Low) = +0.8V, unless otherwise noted.)
-55°C to +125°C
MIN TYP MAX
DYNAMIC
Access Time
Break-Before-Make Delay
(Figure 2)
Enable Delay (ON)
Enable Delay (OFF)
Settling Time (0.1%)
(0.01%)
“OFF Isolation”
Channel Input Capacitance
Channel Output Capacitance
Digital Input Capacitance
Input to Output Capacitance
SUPPLY
Positive Supply Current
Negative Supply Current
Power-Supply Range for
Continuous Operation
I+
I-
V
OP
V
EN
= 0.8V or 2.4V
All V
A
= 0V or 5V
V
EN
= 0.8V or 2.4V
All V
A
= 0V or 5V
(Note 7)
+25°C
Full
+25°C
Full
+25°C
±4.5
0.1
0.3
0.01
0.02
0.6
0.7
0.1
0.2
±18
±4.5
0.2
0.5
0.01
0.02
1.0
1.0
0.1
0.1
±18
mA
mA
V
t
A
t
ON
-t
OFF
t
ON(EN)
t
OFF(EN)
t
SETT
OFF
(ISO)
C
IN(OFF)
C
OUT(OFF)
C
A
C
DS(OFF)
Figure 1
V
EN
= +5V, V
IN
= ±10V
A
0
, A
1
, A
2
strobed
Figure 3
Figure 3
+25°C
+25°C
+25°C
Full
+25°C
Full
+25°C
V
EN
= 0.8V, R
L
= 1kΩ, C
L
= 15pF
+25°C
V = 7V
RMS
, f = 100kHz
+25°C
MAX378
+25°C
MAX379
+25°C
+25°C
50
1.2
3.5
68
5
25
12
5
0.1
50
300
25
0.5
200
400
750
1000
500
1000
1.2
3.5
68
5
25
12
5
0.1
300
1000
1.0
25
0.5
200
400 1000
1500
1.0
µs
ns
ns
ns
µs
dB
pF
pF
pF
pF
0°C to +70°C
and
-40°C to +85°C
MIN TYP MAX
MAX378/MAX379
PARAMETER
SYMBOL
CONDITIONS
TEMP
UNITS
Note 2:
When the analog signal exceeds +13.5V or -12V, the blocking action of Maxim’s gate structure goes into operation. Only
leakage currents flow and the channel ON resistance rises to infinity.
Note 3:
The value shown is the steady-state value. The transient leakage is typically 50µA. See
Detailed Description.
Note 4:
Guaranteed by other static parameters.
Note 5:
Digital input leakage is primarily due to the clamp diodes. Typical leakage is less than 1nA at +25°C.
Note 6:
Leakage currents not tested at T
A
= cold temp.
Note 7:
Electrical characteristics, such as ON Resistance, will change when power supplies other than ±15V are used.
_______________________________________________________________________________________
3
High-Voltage, Fault-Protected
Analog Multiplexers
MAX378/MAX379
__________________________________________Typical Operating Characteristics
INPUT LEAKAGE vs.
INPUT VOLTAGE WITH V+ = V- = 0V
MAX378-1
OFF CHANNEL LEAKAGE CURRENT vs.
INPUT VOLTAGE WITH ±15V SUPPLIES
MAX378-2
OUTPUT LEAKAGE CURRENT vs. OFF CHANNEL
OVERVOLTAGE WITH ±15V SUPPLIES
MAX378-3
1m
100µ
INPUT CURRENT (A)
10µ
OPERATING
RANGE
100µ
10µ
1µ
I
IN(OFF)
(A)
100n
+60V
-60V
10n
1n
100p
OPERATING
RANGE
10n
1n
I
OUT(OFF)
(A)
OPERATING
RANGE
1µ
100n
10n
1n
100p
100p
10p
+80V
-80V
10p
1p
-120
1p
-120
10p
-100
-50
0
V
IN
(V)
50
100
-60
0
V
IN
(V)
60
120
-60
0
V
IN(OFF)
(V)
60
+60V
120
DRAIN-SOURCE ON-RESISTANCE vs.
ANALOG INPUT VOLTAGE
+3.5V
6
+13V
5
R
DS(ON)
(kΩ)
4
3
2
±5V
SUPPLIES
+13V
±15V
SUPPLIES
+4V
MAX3784
7
NOTE:
Typical R
DS(ON)
match @ +10V
Analog in (±15V supplies) = 2%
for lowest to highest R
DS(ON)
channel; @ -10V Analog in,
match = 3%.
1
0
-15
-10
-5
0
5
10
15
20
ANALOG INPUT (V)
MAX378: V
AH
= 3.0V
50%
ADDRESS
DRIVE (V
A
)
0V
V
A
A2
IN1
IN2
A1
+V
AH
50Ω
A0
EN
GND
±10V
MAX378
IN2-IN7
IN8
OUT
10M
14pF
10V
PROBE
±
+10V
OUTPUT A
90%
t
A
-10V
Figure 1. Access Time vs. Logic Level (High)
4
_______________________________________________________________________________________
-60V
High-Voltage, Fault-Protected
Analog Multiplexers
MAX378/MAX379
MAX358: V
AH
= 3.0V
ADDRESS
DRIVE (V
A
)
V
A
2.4V
50%
50%
OUTPUT
50Ω
A2
IN1
IN2
A1
A0
EN
GND
1k
12.5pF
+5V
0V
MAX378*
IN2-IN7
IN8
OUT
V
OUT
t
OPEN
*SIMILAR CONNECTION FOR MAX379
Figure 2. Break-Before-Make Delay (t
OPEN
)
MAX378: V
AH
= 3.0V
ENABLE DRIVE
50%
0V
A2
IN1
+10V
A1
A0
MAX378*
IN2-IN7
90%
OUTPUT
90%
V
A
50Ω
EN
GND
OUT
1k
12.5pF
t
ON(EN)
t
OFF(EN)
*SIMILAR CONNECTION FOR MAX379
Figure 3. Enable Delay (t
ON(EN)
, t
OFF(EN)
)
+5V
+15V
V-
+5V
or
0V
0V
V-
A0
A1
A2
EN
I
±60V
IN1
IN8
V
±10V
ANALOG
SIGNAL
A0
A1
A2
EN
OUT
I
10k
±75V
IN1
MAX378
MAX378
OUT
V-
0V
GND
10k
V-
-15V
GND
Figure 4. Input Leakage Current (Overvoltage)
Figure 5. Input Leakage Current (with Power Supplies OFF)
5
_______________________________________________________________________________________
京公网安备 11010802033920号
EEWORLD
