MAX6397_09 Datasheet, PDF (1/18 Pages) Maxim Integrated Products – Overvoltage Protection Switch/Limiter Controllers Operate Up to 72V

19-3668; Rev 5; 1/09
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Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
General Description
The MAX6397/MAX6398 are small, high-voltage overvolt-
age protection circuits. These devices disconnect the
output load or limit the output voltage during an input
overvoltage condition. These devices are ideal for appli-
cations that must survive high-voltage transients such as
those found in automotive and industrial applications.
The MAX6397/MAX6398 monitor the input or output
voltages and control an external n-channel MOSFET to
isolate or limit the load from overvoltage transient energy.
When the monitored input voltage is below the user-
adjustable overvoltage threshold, the external n-channel
MOSFET is turned on by the GATE output. In this mode,
the internal charge pump fully enhances the n-channel
MOSFET with a 10V gate-to-source voltage.
When the input voltage exceeds the overvoltage thresh-
old, the protection can disconnect the load from the
input by quickly forcing the GATE output low. In some
applications, disconnecting the output from the load is
not desirable. In these cases, the protection circuit can
be configured to act as a voltage limiter where the
GATE output sawtooths to limit the voltage to the load.
The MAX6397 also offers an always-on linear regulator
that is capable of delivering up to 100mA of output
current. This high-voltage linear regulator consumes
only 37µA of quiescent current.
The regulator is offered with output options of 5V, 3.3V,
2.5V, or 1.8V. An open-drain, power-good output (POK)
asserts when the regulator output falls below 92.5% or
87.5% of its nominal voltage.
The MAX6397/MAX6398 include internal thermal-shut-
down protection, disabling the external MOSFET and
linear regulator if the chip reaches overtemperature
conditions. The devices operate over a wide 5.5V to
72V supply voltage range, are available in small TDFN
packages, and are fully specified from -40°C to
+125°C.
Applications
Automotive
Industrial
FireWire^®
Notebook Computers
Wall Cube Power Devices
FireWire is a registered trademark of Apple Computer, Inc.
Features
o 5.5V to 72V Wide Supply Voltage Range
o Overvoltage Protection Controllers Allow User to
Size External n-Channel MOSFETs
o Internal Charge-Pump Circuit Ensures MOSFET
Gate-to-Source Enhancement for Low R_DS(ON)
Performance
o Disconnect or Limit Output from Input During
Overvoltage Conditions
o Adjustable Overvoltage Threshold
o Thermal-Shutdown Protection
o Always-On, Low-Current (37µA) Linear Regulator
Sources Up to 100mA (MAX6397)
o Fully Specified from -40°C to +125°C (T_J)
o Small, Thermally Enhanced 3mm x 3mm TDFN
Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX6397_ATA-T* -40°C to +125°C 8 TDFN-EP**
MAX6398ATT-T*
-40°C to +125°C 6 TDFN-EP**
*Replace “-T” with “+T” for lead(Pb)-free/RoHS-compliant packages.
**EP = Exposed pad.
The MAX6397 linear regulator is offered in four output voltage
options and a choice of a 92.5% or 87.5% POK threshold
assertions. See the Selector Guide.
Selector Guide and Typical Operating Circuit appear at end
of data sheet.
Pin Configurations
TOP VIEW
REG OUT GATE GND
876 5
*EP
MAX6397
1234
IN SHDN SET POK
TDFN
*EXPOSED PAD. CONNECT TO GND.
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.