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 MOSF ET 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 ®我和你不再联系
Notebook Computers Wall Cube Power Devices
Features
♦5.5V to 72V Wide Supply Voltage Range
♦Overvoltage Protection Controllers Allow User to Size External n-Channel MOSFETs ♦Internal Charge-Pump Circuit Ensures MOSFET Gate-to-Source Enhancement for Low R DS(ON)Performan
ce ♦Disconnect or Limit Output from Input During Overvoltage Conditions ♦Adjustable Overvoltage Threshold ♦Thermal-Shutdown Protection
♦Always-On, Low-Current (37µA) Linear Regulator Sources Up to 100mA (MAX6397)♦Fully Specified from -40°C to +125°C (T J )♦Small, Thermally Enhanced 3mm x 3mm TDFN Package
MAX6397/MAX6398
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
________________________________________________________________Maxim Integrated Products
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Pin Configurations
Ordering Information
19-3668; Rev 3; 1/07
For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.
Selector Guide and Typical Operating Circuit appear at end of data sheet.
FireWire is a registered trademark of Apple Computer, Inc.
M A X 6397/M A X 6398
Overvoltage Protection Switch/Limiter Controllers Operate Up to 72V 2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
= 14V; C = 6000pF, C = 4.7µF, T = T = -40°C to +125°C, unless otherwise noted. Typical values are at T = T = +25°C.)(Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional oper-ation 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.
(All pins referenced to GND, unless otherwise noted.)
IN, GATE, -0.3V to +80V SHDN ..................................................................-0.3V to (IN + 0.3V)GATE .-0.3 to +20V SET, REG, -0.3V to +12V Maximum Current:
IN, .350mA All 50mA
周杰伦所有专辑>单恋一枝花Continuous Power Dissipation (T A = +70°C)
6-Pin TDFN (derate 18.2mW/°C above +70°C).............1455mW 8-Pin TDFN (derate 18.2mW/°C above +70°C).............1455mW Operating Temperature Range (T A )......................-40°C to +125°C +150°C Storage -65°C to +150°C +300°C
MAX6397/MAX6398
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
_______________________________________________________________________________________3
ELECTRICAL CHARACTERISTICS (continued)
(V IN = 14V; C GATE = 6000pF, C REG = 4.7µF, T A = T J = -40°C to +125°C, unless otherwise noted. Typical values are at T A = T J = +25°C.)(Note 1)
Note 1:Specifications to -40°C are guaranteed by design and not production tested.
Note 2:The MAX6397/MAX6398 power up with the external FET in off mode (V GATE = GND). The external FET turns on t START after the
device is powered up and all input conditions are valid.
Note 3:For accurate overtemperature shutdown performance, place the device in close thermal contact with the external MOSFET.Note 4:Dropout voltage is defined as V IN - V REG when V REG is 2% below the value of V REG for V IN = V REG (nominal) + 2V.Note 5:Operations beyond the thermal dissipation limit may permanently damage the device.
M A X 6397/M A X 6398
Overvoltage Protection Switch/Limiter Controllers Operate Up to 72V 4_______________________________________________________________________________________
Typical Operating Characteristics
(V IN = 14V, C REG = 4.7µF, I REG = 0, unless otherwise noted.)
40
60801001201401600
2010304050607080SUPPLY CURRENT vs. INPUT VOLTAGE
INPUT VOLTAGE (V)S U P P L Y  C U R R E N T  (µA )SUPPLY CURRENT vs. TEMPERATURE
TEMPERATURE (°C)
S U P P L Y  C U R R E N T  (µA )
1007525500-2590100110
12013014015016017018080
-5012540
5060708090100110120
02040
6080
范美熙
SUPPLY CURRENT vs. INPUT VOLTAGE
INPUT VOLTAGE (V)
S U P P L Y  C
U R R E N T  (µA )8010090120110130140-50
2550-25075100125
SUPPLY CURRENT vs. TEMPERATURE
TEMPERATURE (°C)
S U P P L Y
C U R R E N T  (µA )
20
302540354550040206080
SHUTDOWN SUPPLY CURRENT vs. INPUT VOLTAGE (MAX6397)
INPUT VOLTAGE (V)
S U P P L Y
C U R R E N T  (µA )
103050700642
8101214161820
20
40
60
80
SHUTDOWN SUPPLY CURRENT
vs. INPUT VOLTAGE
INPUT VOLTAGE (V)
S U P P
L Y  C U R R E N T  (µA )
0642810124
121068141618202224GATE-DRIVE VOLTAGE vs. INPUT VOLTAGE
INPUT VOLTAGE (V)
V G A T E  - V O U T  (V )
4.0
4.64.44.2
5.04.85.85.65.45.2
6.0-50-250255075100125UVLO THRESHOLD vs. TEMPERATURE
M A X 6397-98 t o c 08
TEMPERATURE (°C)V U V L O  (V )
SET THRESHOLD vs. TEMPERATURE
M A X 6397-98 t o c 09
TEMPERATURE (°C)
S E T  T H R E S H O L D  (V )1007525500-251.2041.2081.2121.2161.2201.2241.2281.2321.2361.240
1.200
-50125
MAX6397/MAX6398
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
_______________________________________________________________________________________5
16.0
16.316.216.116.516.416.916.816.716.617.0-50
-25
25
50
75
100
125GATE-TO-OUT CLAMP VOLTAGE
vs. TEMPERATURE
M A X 6397-98 t o c 10
TEMPERATURE (°C)G A T E -T O -O U T  C L A M P  V O L T A G E  (V )0
0.40.20.80.61.21.01.41.81.62.0040608020100120140160180DROPOUT VOLTAGE vs. REG LOAD CURRENT
REG LOAD CURRENT (mA)
D R O P O U T  V O L T A G
E  (V )
4.90
5.004.955.10
5.055.155.20
-40-10520-253550658095110
125
REG OUTPUT VOLTAGE
vs. LOAD CURRENT AND TEMPERATURE
TEMPERATURE (°C)
R E G  O U T P U T  V O L T A G E  (V )4.0
4.64.44.24.8
5.05.2
1601204080200240280320360400
MAXIMUM REG OUTPUT VOLTAGE vs. LOAD CURRENT AND TEMPERATURE
LOAD CURRENT (mA)
R E G  O U T P U T  V O L T A G E  (V )
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
FREQUENCY (Hz)
P S R R  (d B )
1M 100k 10k 1k 100-60-50-40-30-20-100
-70
1010M
4ms/div
STARTUP WAVEFORM
(R LOAD  = 100Ω, C IN  = 10µF, C OUT  = 10µF)
V IN 10V/div
MAX6397-98 toc16
V GATE 10V/div V OUT 10V/div I OUT
200mA/div
400µs/div
STARTUP WAVEFORM FROM SHUTDOWN
(C IN  = 10µF, C OUT  = 10µF)
V 2V/div
V GATE 10V/div
V OUT 10V/div I OUT
200mA/div
R LOAD  = 100Ω
Typical Operating Characteristics (continued)
(V IN = 14V, C REG = 4.7µF, I REG = 0, unless otherwise noted.)
GATE-DRIVE VOLTAGE vs. TEMPERATURE
M A X 6397-98 t o c 14
TEMPERATURE (°C)G A T E -D R I V E  V O L T A G E  (V )1007525500-2510.45510.46010.46510.47010.47510.48010.48510.49010.49510.50010.450
-50125
M A X 6397/M A X 6398
Overvoltage Protection Switch/Limiter Controllers Operate Up to 72V 6_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V IN = 14V, C REG = 4.7µF, I REG = 0, unless otherwise noted.)
200µs/div
OVERVOLTAGE SWITCH FAULT
V IN 20V/div
V GATE 20V/div V OUT 20V/div V REG 5V/div
V OV  = 30V
1ms/div
VOLTAGE LIMIT FAULT
V IN 20V/div
V GATE 20V/div
V OUT 20V/div V REG 5V/div
V OV  = 30V
400µs/div
TRANSIENT RESPONSE
V IN 10V/div
V REG
100mV/div
C REG  = 10µF I REG  = 10mA
1ms/div
REG LOAD-TRANSIENT RESPONSE
V REG
AC-COUPLED 500mV/div
I REG
miracles
100mA/div
C REG  = 10µF
1ms/div
REGULATOR STARTUP WAVEFORM
V IN 10V/div
V POK 2V/div
V REG 2V/div
I REG  = 10mA
100µs/div
REGULATOR POK ASSERTION
V REG 2V/div
I REG
200mA/div V POK 2V/div
I REG  = 0
0V
0V
0A