19-3778; Rev 8; 1/11
IT
TION K
VALUA
E
BLE
AVAILA
72V, Overvoltage-Protection Switches/
Limiter Controllers with an External MOSFET
General Description
The MAX6495–MAX6499 is a family of small, low-cur-
rent, overvoltage-protection circuits for high-voltage
transient systems such as those found in automotive
and industrial applications. These devices monitor the
input voltage and control an external n-channel MOSFET
switch to isolate the load at the output during an input
overvoltage condition. The MAX6495–MAX6499 operate
over a wide supply voltage range from +5.5V to +72V.
The gate of the n-channel MOSFET is driven high while
the monitored input is below the user-adjustable over-
voltage threshold. An integrated charge-pump circuit
provides a 10V gate-to-source voltage to fully enhance
the n-channel MOSFET. When the input voltage
exceeds the user-adjusted overvoltage threshold, the
gate of the MOSFET is quickly pulled low, disconnect-
ing the load from the input. In some applications, dis-
connecting 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 saw-
tooths to limit the voltage to the load (MAX6495/
MAX6496/MAX6499).
The MAX6496 supports lower input voltages and
reduces power loss by replacing the external reverse
battery diode with an external series p-channel MOSFET.
The MAX6496 generates the proper bias voltage to
ensure that the p-channel MOSFET is on during normal
operations. The gate-to-source voltage is clamped dur-
ing load-dump conditions, and the p-channel MOSFET
is off during reverse-battery conditions.
The MAX6497/MAX6498 feature an open-drain, undedi-
cated comparator that notifies the system if the output
falls below the programmed threshold. The MAX6497
keeps the MOSFET switch latched off until either the
input power or the
SHDN
pin is cycled. The MAX6498
will autoretry when V
OVSET
falls below 130mV.
These devices are available in small, thermally
enhanced, 6-pin and 8-pin TDFN packages and are
fully specified from -40°C to +125°C.
Features
♦
Wide Supply Voltage Range: +5.5V to +72V
♦
Overvoltage-Protection Switch Controller Allows
User to Size External n-Channel MOSFETs
♦
Fast Gate Shutoff During Overvoltage with 100mA
Sink Capability
♦
Internal Charge-Pump Circuit Ensures 10V
Gate-to-Source Enhancement for Low R
DS(ON)
Performance
♦
n-Channel MOSFET Latches Off After an
Overvoltage Condition (MAX6497/MAX6499)
♦
Adjustable Overvoltage Threshold
♦
Thermal Shutdown Protection
♦
Supports Series p-Channel MOSFET for Reverse-
Battery Voltage Protection (MAX6496)
♦
POK Indicator (MAX6497/MAX6498)
♦
Adjustable Undervoltage Threshold (MAX6499)
♦
-40°C to +125°C Operating Temperature Range
♦
Small, 3mm x 3mm TDFN Package
MAX6495–MAX6499
Ordering Information
PART
MAX6495ATT+T
MAX6495ATT/V+T
PIN-PACKAGE
6 TDFN-EP*
6 TDFN-EP*
TOP MARK
AJM
AUG
Ordering Information continued at end of data sheet.
Note:
All devices are specified over the -40°C to +125°C operating
temperature range.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*EP
= Exposed pad.
/V
denotes an automotive qualified part.
Selector Guide appears at end of data sheet.
Pin Configurations
TOP VIEW
OUTFB
6
GATE
5
GND
4
Applications
Automotive
Industrial
Telecom/Servers/Networking
FireWire
®
Notebook Computers
1
IN
MAX6495
2
SHDN
3
OVSET
3mm x 3mm TDFN
FireWire is a registered trademark of Apple Computer, Inc.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
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.
72V, Overvoltage-Protection Switches/
Limiter Controllers with an External MOSFET
MAX6495–MAX6499
ABSOLUTE MAXIMUM RATINGS
(All pins referenced to GND.)
IN, GATE, GATEP ...................................................-0.3V to +80V
SHDN, CLEAR
.............................................-0.3V to (V
IN
+ 0.3V)
POK, OUTFB ..........................................................-0.3V to +80V
GATE to OUTFB .....................................................-0.3V to +12V
GATEP to IN ...........................................................-12V to +0.3V
OVSET, UVSET, POKSET .......................................-0.3V to +12V
Current Sink/Source (All Pins).............................................50mA
All Other Pins to GND ..................................-0.3V to (V
IN
+ 0.3V)
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 .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°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
IN
= 14V, C
GATE
= 6nF, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
SYMBOL
V
IN
SHDN
= high
SHDN
= low (MAX6497/MAX6498/
MAX6499)
SHDN
= low (MAX6495/MAX6496)
IN Undervoltage Lockout
IN Undervoltage Lockout
Hysteresis
OVSET Threshold Voltage
(MAX6495/MAX6496)
OVSET Threshold Hysteresis
(MAX6495/MAX6496)
OVSET Threshold Voltage
(MAX6497/MAX6498)
OVSET Threshold Voltage
(MAX6499)
UVSET Threshold Voltage
(MAX6499)
OVSET/UVSET Threshold
Hysteresis (MAX6499)
POKSET Threshold Voltage
(MAX6497/MAX6498)
POKSET Threshold
Hysteresis (MAX6497/
MAX6498)
OVSET, UVSET, POKSET
Input Current
Startup Response Time
GATE Rise Time
V
TH+
V
TH-
V
HYST
V
TH+
V
TH-
V
TH+
V
TH-
V
TH+
V
TH-
V
HYST
V
IN
rising, enables GATE
V
IN
falling, disables GATE
OVSET rising
OVSET falling
OVSET falling
OVSET rising
OVSET falling
OVSET rising
OVSET falling
UVSET rising
UVSET falling
OVSET falling
1.22
1.22
1.22
0.494
1.22
4.75
CONDITIONS
MIN
5.5
100
15
24
5
155
1.24
1.18
5
0.505
0.13
1.24
1.18
1.24
1.18
5
1.24
1.18
5
1.26
1.26
1.26
0.518
1.26
TYP
MAX
72.0
150
24
32
5.25
V
mV
V
%
V
V
V
%
V
µA
UNITS
V
Input Supply Current
I
IN
No load
V
POKSET+
POKSET rising
V
POKSET-
POKSET falling
V
HYST
POKSET falling
%
I
SET
t
START
SHDN
rising (Note 2)
GATE rising from GND to V
OUTFB
+ 8V,
OUTFB = GND
-50
100
1
+50
nA
µs
ms
2
_______________________________________________________________________________________
72V, Overvoltage-Protection Switches/
Limiter Controllers with an External MOSFET
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 14V, C
GATE
= 6nF, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
OVSET to GATE Propagation
Delay
UVSET to GATE, POKSET to
POK Propagation Delay
GATE Output High Voltage
GATE Output Low Voltage
GATE Charge-Pump Current
GATE to OUTFB Clamp
Voltage
IN to GATEP Output Low
Voltage
IN to GATEP Clamp Voltage
SHDN, CLEAR
Logic-High
Input Voltage
SHDN, CLEAR
Logic-Low
Input Voltage
SHDN
Input Pulse Width
CLEAR
Input Pulse Width
SHDN, CLEAR
Input
Pulldown Current
Thermal Shutdown
Thermal-Shutdown
Hysteresis
POKSET to POK Delay
(MAX6497/MAX6498)
POK Output Low Voltage
(MAX6497/MAX6498)
POK Leakage Current
(MAX6497/MAX6498)
V
OL
V
IN
≥
14V, POKSET = GND, I
SINK
= 3.2mA
V
IN
≥
2.8V, POKSET = GND, I
SINK
= 100µA
V
POKSET
= 14V
SHDN
is Internally pulled down to GND
(Note 3)
0.6
V
IH
V
IL
7
0.5
1.0
+160
20
35
0.4
0.4
100
1.4
V
OH
V
OL
I
GATE
V
CLMP
I
GATEP
_
SINK
= 75µA, I
GATEP
_
SOURCE
= 1µA
V
IN
= 24V, I
GATEP
_
SOURCE
= 10µA
SYMBOL
t
OV
CONDITIONS
SET rising from V
TH
- 100mV to V
TH
+ 100mV
POKSET, UVSET falling from V
TH
+ 100mV to
V
TH
- 100mV
V
OUTFB
= V
IN
= 5.5V, R
GATE
to IN = 1MΩ
V
OUTFB
= V
IN,
V
IN
≥
14V, R
GATE
to IN = 1MΩ
GATE sinking 15mA, OUTFB = GND
V
IN
= 5.5V, GATE sinking 1mA, OUTFB = GND
GATE = GND
12
7.5
12
1.4
V
0.4
µs
µs
µA
°C
°C
µs
V
nA
100
18
11.7
18
V
IN
+ 8
20
V
IN
+ 3.4 V
IN
+ 3.8 V
IN
+ 4.2
V
IN
+ 10
V
IN
+ 11
1
0.9
MIN
TYP
MAX
0.6
UNITS
µs
µs
V
V
µA
V
V
V
MAX6495–MAX6499
Note 1:
Specifications to T
A
= -40°C are guaranteed by design and not production tested.
Note 2:
The MAX6495–MAX6499 power up with the external MOSFET in off mode (V
GATE
= GND). The external MOSFET turns on
t
START
after all input conditions are valid.
Note 3:
For accurate overtemperature-shutdown performance, place the device in close thermal contact with the external MOSFET.
_______________________________________________________________________________________
3
72V, Overvoltage-Protection Switches/
Limiter Controllers with an External MOSFET
MAX6495–MAX6499
Typical Operating Characteristics
(V
IN
= +12V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6495 toc01
SUPPLY CURRENT vs. TEMPERATURE
MAX6495 toc02
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SHUTDOWN SUPPLY CURRENT (µA)
SET = GND, SHDN = GND
MAX6496
40
MAX6495 toc03
120.0
SET = GND, GATE ENHANCED
117.5
SUPPLY CURRENT (µA)
115.0
112.5
110.0
107.5
105.0
50
135
SUPPLY CURRENT (µA)
110
85
60
35
10
5
SET = GND, GATE ENHANCED
30
20
102.5
100.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
10
5
15
25
35
45
55
65
75
SUPPLY VOLTAGE (V)
15
25
35
45
55
65
75
SUPPLY VOLTAGE (V)
GATE VOLTAGE vs. SUPPLY VOLTAGE
MAX6495 toc04
GATEP VOLTAGE vs. SUPPLY VOLTAGE
MAX6495 toc05
UVLO THRESHOLD vs. TEMPERATURE
5.4
5.3
UVLO THRESHOLD (V)
5.2
5.1
5.0
4.9
4.8
4.7
4.6
FALLING
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
RISING
SET = GND, IN = OUTFB = SHDN
MAX6495 toc06
12
SET = GND, IN = OUTFB = SHDN
9
12
SET = GND, IN = OUTFB = SHDN
9
V
IN
- V
GATEP
(V)
5.5
V
GATE
- V
IN
(V)
6
6
3
3
0
5
15
25
35
45
55
65
75
SUPPLY VOLTAGE (V)
0
5
15
25
35
45
55
65
75
SUPPLY VOLTAGE (V)
4.5
SET THRESHOLD vs. TEMPERATURE
MAX6495 toc07
GATE TO OUTFB CLAMP VOLTAGE
vs. TEMPERATURE
16.4
16.3
V
GATE
- V
OUTFB
(V)
16.2
16.1
16.0
15.9
15.8
15.7
SET = OUTFB = GND
IN = SHDN
MAX6495 toc08
1.40
IN = SHDN
1.35
SET THRESHOLD (V)
1.30
1.25
1.20
1.15
FALLING
1.10
RISING
16.5
15.6
15.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
4
_______________________________________________________________________________________
72V, Overvoltage-Protection Switches/
Limiter Controllers with an External MOSFET
Typical Operating Characteristics (continued)
(V
IN
= +12V, T
A
= +25°C, unless otherwise noted.)
MAX6495–MAX6499
STARTUP WAVEFORM
(C
IN
= 100µF, C
OUT
= 10µF, R
OUT
= 100Ω)
MAX6495 toc09
STARTUP FROM SHUTDOWN
(C
IN
= 100µF, C
OUT
= 10µF, R
OUT
= 100Ω)
MAX6495 toc10
V
IN
10V/div
V
GATE
10V/div
V
SHDN
1V/div
V
GATE
10V/div
V
OUT
10V/div
V
OUT
10V/div
400µs/div
400µs/div
OVERVOLTAGE SWITCH FAULT
(C
IN
= 100µF, C
OUT
= 10µF, R
OUT
= 100Ω)
MAX6495 toc11
OVERVOLTAGE LIMITER
(C
IN
= 100µF, C
OUT
= 10µF, R
OUT
= 100Ω)
MAX6495 toc12
V
IN
20V/div
V
IN
20V/div
V
GATE
20V/div
V
GATE
20V/div
V
OUT
20V/div
200µs/div
V
OUT
20V/div
TRIP THRESHOLD = 28V
400µs/div
_______________________________________________________________________________________
5
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