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 current 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 firstgeneration fault-protected muxes. First, the Maxim protection scheme limits fault currents to nanoamp leakage
values rather than many milliamperes. This prevents damage 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 requiring pull-up resistors. Break-before-make operation is
guaranteed. Power dissipation is less than 2mW.
________________________Applications
Data Acquisition Systems
Industrial and Process Control Systems
Avionics Test Equipment
Signal Routing Between Systems
____________________________Features
♦ Fault Input Voltage ±75V with Power Supplies Off
♦ Fault Input Voltage ±60V with ±15V Power Supplies
♦ All Switches Off with Power Supplies Off
♦ On Channel Turns OFF if Overvoltage Occurs on
Input or Output
♦ Only Nanoamperes of Input Current Under All
Fault Conditions
♦ No Increase in Supply Currents Due to Fault
Conditions
♦ Latchup-Proof Construction
♦ Operates from ±4.5V to ±18V Supplies
♦ All Digital Inputs are TTL and CMOS Compatible
♦ Low-Power Monolithic CMOS Design
______________Ordering Information
PART
MAX378CPE
MAX378CWG
MAX378CJE0°C to +70°C
MAX378C/D0°C to +70°CDice**
MAX378EPE
MAX378EWG-40°C to +85°C
MAX378EJE
MAX378MJE-55°C to +125°C
MAX378MLP-55°C to +125°C20 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).
Call toll free 1-800-998-8800 for free samples or literature.
1
High-Voltage, Fault-Protected
Analog Multiplexers
ABSOLUTE MAXIMUM RATINGS
Voltage between Supply Pins..............................................+44V
V+ to Ground...................................................................+22V
V- to Ground......................................................................-22V
Digital Input Overvoltage:
VEN, V
Analog Input with Multiplexer Power On..............................±65V
Analog Input with Multiplexer Power Off..............................±80V
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 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
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
Note 7: Electrical characteristics, such as ON Resistance, will change when power supplies other than ±15V are used.