19-3668; Rev 5; 1/09
IT
TION K
VALUA
E
BLE
AVAILA
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
General Description
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
MAX6397/MAX6398
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.
Ordering Information
PART
MAX6397_ATA-T*
MAX6398ATT-T*
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 TDFN-EP**
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
8
*EP
OUT
7
GATE GND
6
5
Applications
Automotive
Industrial
FireWire
®
Notebook Computers
Wall Cube Power Devices
MAX6397
1
IN
2
SHDN
3
SET
4
POK
FireWire is a registered trademark of Apple Computer, Inc.
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.
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
MAX6397/MAX6398
ABSOLUTE MAXIMUM RATINGS
(All pins referenced to GND, unless otherwise noted.)
IN, GATE, OUT ............................................................-0.3V to +80V
SHDN..................................................................-0.3V
to (IN + 0.3V)
GATE to OUT .................................................................-0.3 to +20V
SET, REG, POK ...........................................................-0.3V to +12V
Maximum Current:
IN, REG...............................................................................350mA
All Remaining Pins ...................................................................50mA
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
Junction Temperature ...........................................................+150°C
Storage Temperature Range .................................-65°C to +150°C
Lead Temperature ................................................................+300°C
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.
ELECTRICAL CHARACTERISTICS
(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)
PARAMETER
Supply Voltage Range
SYMBOL
V
IN
SHDN
= high, no load (MAX6397)
Input Supply Current
SHDN
= high, (MAX6398)
SHDN
= low, no load (MAX6397)
SHDN
= low, (MAX6398)
IN Undervoltage Lockout
IN Undervoltage Lockout
Hysteresis
SET Threshold Voltage
SET Threshold Hysteresis
SET Input Current
Startup Response Time
GATE Rise Time
SET to GATE Propagation Delay
t
OV
V
TH
V
HYST
I
SET
t
START
SHDN
rising (Note 2)
GATE rising from GND to V
OUT
+ 8V,
C
GATE
= 6000pF, OUT = GND
SET rising from V
TH
- 100mV to V
TH
+
100mV
V
OUT
= V
IN
= 6V, R
GATE
to IN = 1MΩ
GATE Output High Voltage
V
OH
V
OUT
= V
IN
; V
IN
≥
14V, R
GATE
to IN = 1MΩ
GATE Output Low Voltage
GATE Charge-Pump Current
GATE to OUT Clamp Voltage
SHDN
Logic-High Input Voltage
SHDN
Logic-Low Input Voltage
SHDN
Input Pulldown Current
Thermal Shutdown
Thermal Shutdown Hysteresis
REGULATOR (MAX6397)
Ground Current
I
GND
SHDN
= GND
I
REG
= 1mA
I
REG
= 100mA
40
60
48
µA
V
OL
I
GATE
V
CLMP
V
IH
V
IL
V
SHDN
= 2V,
SHDN
is internally pulled
down to GND
(Note 3)
1
+150
20
GATE sinking 20mA, V
OUT
= GND
GATE = GND
13
1.4
0.4
µA
°C
°C
75
18
V
IN
+
3.8V
V
IN
+
8.5V
V
IN
+
4.2V
V
IN
+
9.2V
-50
100
1
0.75
V
IN
+
4.6V
V
V
IN
+
11.5V
0.38
V
µA
V
V
IN
rising, enables GATE
V
IN
falling, disables GATE
With respect to GND
1.181
4.66
CONDITIONS
MIN
5.5
118
104
37
11
5
175
1.215
4
+50
1.248
TYP
MAX
72
140
130
45
20
5.50
V
mV
V
%
nA
µs
ms
µs
µA
UNITS
V
2
_______________________________________________________________________________________
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
MAX6397/MAX6398
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)
PARAMETER
SYMBOL
MAX6397L/M
MAX6397S/T
REG Output Voltage
(V
IN
≥
V
REG
+ 1.8V)
V
REG
MAX6397Y/Z
MAX6397V/W
Dropout Voltage (Note 4)
Current Limit
Overvoltage-Protection Threshold
Overvoltage-Protection Sink Current
Line Regulation (Note 5)
V
OVP
I
OVP
∆
V
REG
/
∆V
REG
∆VREG
/
∆IREG
t
START
V
REG
= 1.1 x V
REG
(nominal)
6.5V
≤
V
IN
≤
72V, I
REG
= 10mA, V
REG
= 5V
5.5V
≤
V
IN
≤
72V, I
REG
= 1mA, V
REG
= 5V
5.5V
≤
V
IN
≤
72V, I
REG
= 100mA, V
REG
= 5V
1mA
≤
I
REG
≤
100mA, V
REG
= 5V
I
REG
= 10mA, f = 100Hz, 0.5V
P-P
R
REG
= 500Ω, V
REG
= 5V, C
REG
= 4.7µF
L
M
T
POK Assertion Threshold
(MAX6397 Only)
V
POK_TH
S
Z
Y
W
V
REG to POK Delay
POK Leakage Current
POK Output Low Voltage
V
OL
V
REG
rising or falling
V
POK
= 5V
V
IN
≥
1.5V, I
SINK
= 1.6mA, POK asserted
4.500
4.230
2.966
2.805
2.250
2.125
1.590
1.524
55
180
4.67
4.375
3.053
2.892
2.304
2.188
1.653
1.575
35
300
0.3
4.780
4.500
3.140
2.970
2.375
2.250
1.696
1.625
µs
nA
V
V
1.5
0.8
mV/mA
dB
µs
∆V
DO
CONDITIONS
I
REG
= 1mA
1mA < I
REG
< 100mA
I
REG
= 1mA
1mA < I
REG
< 100mA
I
REG
= 1mA
1mA < I
REG
< 100mA
I
REG
= 1mA
1mA < I
REG
< 100mA
MIN
4.925
4.85
3.243
3.201
2.456
2.41
1.760
1.715
1.8
2.5
3.3
TYP
5
MAX
5.120
5.15
3.360
3. 360
2.542
2.55
1.837
1.837
0.12
1.2
150
105
15
0.22
0.05
mV/V
300
mA
% of
V
REG
mA
mV/V
V
UNITS
5.5V
≤
V
IN
≤
72V, I
REG
= 1mA, V
REG
= 5V
5.5V
≤
V
IN
≤
72V, I
REG
= 100mA, V
REG
= 5V
V
IN
= 14V
Load Regulation
Power-Supply Rejection Ratio
Startup Response Time
Note 1:
Specifications to T
A
= -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.
_______________________________________________________________________________________
3
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
MAX6397/MAX6398
Typical Operating Characteristics
(V
IN
= 14V, C
REG
= 4.7µF, I
REG
= 0, unless otherwise noted.)
SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX6397-98 toc01
SUPPLY CURRENT vs. TEMPERATURE
MAX6397-98 toc02
SUPPLY CURRENT
vs. INPUT VOLTAGE
110
SUPPLY CURRENT (µA)
100
90
80
70
60
50
40
MAX6398
GATE ON
MAX6397-98 toc03
160
140
SUPPLY CURRENT (µA)
120
100
80
60
40
0
10
20
30
40
50
60
70
MAX6397
GATE ON
180
170
160
SUPPLY CURRENT (µA)
150
140
130
120
110
100
90
80
MAX6397
120
V
IN
= 72V
V
IN
= 14V
80
-50
-25
0
25
50
75
100
125
0
20
40
INPUT VOLTAGE (V)
60
80
INPUT VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY CURRENT
vs. TEMPERATURE
MAX6397-98 toc04
SHUTDOWN SUPPLY CURRENT
vs. INPUT VOLTAGE (MAX6397)
MAX6397-98 toc05
SHUTDOWN SUPPLY CURRENT
vs. INPUT VOLTAGE
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
MAX6398
GATE OFF
MAX6397-98 toc06
140
130
SUPPLY CURRENT (µA)
120
110
100
90
80
-50
-25
0
25
50
75
100
V
IN
= 14V
MAX6398
GATE ON
50
45
SUPPLY CURRENT (µA)
40
35
30
25
20
REGULATOR ON
GATE OFF
20
V
IN
= 72V
0
0
10
20
30
40
50
60
70
80
0
20
40
INPUT VOLTAGE (V)
60
80
INPUT VOLTAGE (V)
125
TEMPERATURE (°C)
GATE-DRIVE VOLTAGE
vs. INPUT VOLTAGE
MAX6397-98 toc07
UVLO THRESHOLD
vs. TEMPERATURE
MAX6397-98 toc08
SET THRESHOLD vs. TEMPERATURE
1.236
1.232
SET THRESHOLD (V)
1.228
1.224
1.220
1.216
1.212
1.208
1.204
1.200
MAX6397-98 toc09
12
V
OUT
= V
IN
10
V
GATE
- V
OUT
(V)
8
6.0
5.8
5.6
5.4
V
UVLO
(V)
5.2
5.0
4.8
4.6
4.4
4.2
1.240
6
4
2
0
4
6
8
10 12 14 16 18 20 22 24
INPUT VOLTAGE (V)
4.0
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
Typical Operating Characteristics (continued)
(V
IN
= 14V, C
REG
= 4.7µF, I
REG
= 0, unless otherwise noted.)
MAX6397/MAX6398
GATE-TO-OUT CLAMP VOLTAGE
vs. TEMPERATURE
MAX6397-98 toc10
DROPOUT VOLTAGE
vs. REG LOAD CURRENT
1.8
1.6
DROPOUT VOLTAGE (V)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
T
A
= +25°C
T
A
= -40°C
T
A
= +125°C
MAX6397L
MAX6397-98 toc11
REG OUTPUT VOLTAGE
vs. LOAD CURRENT AND TEMPERATURE
MAX6397L
5.15
REG OUTPUT VOLTAGE (V)
5.10
I
LOAD
= 10mA
5.05
5.00
4.95
4.90
I
LOAD
= 100mA
I
LOAD
= 50mA
MAX6397-98 toc12
17.0
GATE-TO-OUT CLAMP VOLTAGE (V)
16.9
16.8
16.7
16.6
16.5
16.4
16.3
16.2
16.1
16.0
-50
-25
0
25
50
75
100
2.0
5.20
125
0
20
40
60
80 100 120 140 160 180
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
REG LOAD CURRENT (mA)
MAXIMUM REG OUTPUT VOLTAGE
vs. LOAD CURRENT AND TEMPERATURE
MAX6397-98 toc13
GATE-DRIVE VOLTAGE
vs. TEMPERATURE
MAX6397-98 toc14
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
C
REG
= 10µF
I
REG
= 10mA
MAX6397-98 toc15
5.2
T
A
= -40°C
5.0
REG OUTPUT VOLTAGE (V)
4.8
T
A
= +25°C
4.6
4.4
4.2
4.0
0
T
A
= +125°C
THERMAL
SHUTDOWN
10.500
10.495
GATE-DRIVE VOLTAGE (V)
10.490
10.485
0
-10
-20
PSRR (dB)
-30
-40
-50
-60
-70
10.480
10.475
10.470
10.465
10.460
10.455
10.450
40 80 120 160 200 240 280 320 360 400
LOAD CURRENT (mA)
-50
-25
0
25
50
75
100
125
10
100
1k
10k
100k
1M
10M
TEMPERATURE (°C)
FREQUENCY (Hz)
STARTUP WAVEFORM
(R
LOAD
= 100Ω, C
IN
= 10µF, C
OUT
= 10µF)
MAX6397-98 toc16
STARTUP WAVEFORM FROM SHUTDOWN
(C
IN
= 10µF, C
OUT
= 10µF)
MAX6397-98 toc17
R
LOAD
= 100Ω
V
IN
10V/div
V
SHDN
2V/div
V
GATE
10V/div
V
GATE
10V/div
V
OUT
10V/div
I
OUT
200mA/div
4ms/div
400µs/div
V
OUT
10V/div
I
OUT
200mA/div
_______________________________________________________________________________________
5
