MAX16997 Datasheet PDF - Maxim Integrated Products


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MAX16997
Maxim Integrated Products

Part Number MAX16997
Description (MAX16997 / MAX16998) High-Voltage Watchdog Timers
Page 16 Pages

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19-4000; Rev 1; 4/09
High-Voltage Watchdog Timers with
Adjustable Timeout Delay
General Description
The MAX16997/MAX16998 are microprocessor (µP)
supervisory circuits for high-input-voltage and low-qui-
escent-current applications. These devices detect
downstream circuit failures and provide switchover to
redundant circuitry. See the Selector Guide for the dif-
ferent versions of this product family.
The MAX16997/MAX16998 family has four independent
inputs for reset and watchdog functions. SWT and SRT
inputs independently set the timeout periods of watch-
dog and reset timers through external capacitors.
RESETIN/EN monitor voltages at respective inputs. A
resistive voltage-divider sets the reset threshold.
The MAX16998A/B/D generate two output signals,
RESET and ENABLE. RESET asserts whenever
RESETIN drops below its threshold voltage or when the
watchdog timer detects a timing fault at WDI. Once
asserted, and after all reset conditions are removed,
RESET remains low for the reset timeout period, tRESET,
and then goes high. The MAX16997A generates one
output signal (ENABLE) based on the voltage level at
EN and the signal at WDI.
The MAX16997A does not have a RESET output. The
watchdog is disabled if the voltage at EN is below its
threshold. The MAX16997A watchdog timer starts tim-
ing when the voltage at EN becomes higher than the
preset threshold voltage level. Each time EN rises
above the preset threshold voltage, the initial watchdog
timeout period is 8 times the normal watchdog timeout
period (tWP).
The MAX16997/MAX16998 are available in 8-pin lead-
free µMAX® packages and are fully specified over the
-40°C to +125°C automotive temperature range.
Automotive
Industrial
Applications
Features
o Wide 5V to 40V Input Voltage Range
o 18µA Quiescent Current (Typical at +125°C)
o Capacitor-Adjustable Timeout Period for
Watchdog and Reset
o Windowed Watchdog Timer Options
(MAX16998B/D)
o External Voltage Monitoring (RESETIN for the
MAX16998A/B/D and EN for the MAX16997A)
o Car Battery-Compatible EN Input
o TTL- and CMOS-Compatible Open-Drain Outputs
o 18V Maximum Open-Drain Reset Output Voltage
o 28V Maximum Open-Drain Enable Output Voltage
o Power-On/Power-Off Reset Functionality
(MAX16998A/B/D Only)
o AECQ-100 Qualified
o -40°C to +125°C Operating Temperature Range
o Small (3mm x 3mm) µMAX Package
http://www.DataSheet4U.net/
o WDI Narrow Pulse Immunity
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX16997AAUA+
-40°C to +125°C 8 µMAX
MAX16998AAUA+
-40°C to +125°C 8 µMAX
MAX16998BAUA+
-40°C to +125°C 8 µMAX
MAX16998DAUA+
-40°C to +125°C 8 µMAX
+Denotes a lead(Pb)-free/RoHS-compliant package.
Selector Guide
PART
WATCHDOG
WINDOW SIZE (%)
ENABLE
MAX16997A
MAX16998A
100
100
MAX16998B
MAX16998D
50
75
Pin Configurations appear at end of data sheet.
RESET
EN RESETIN
µMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ 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.



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High-Voltage Watchdog Timers with
Adjustable Timeout Delay
ABSOLUTE MAXIMUM RATINGS
(All pins referenced to GND, unless otherwise noted.)
IN, ENABLE ............................................................-0.3V to +45V
WDI, RESET, EN .....................................................-0.3V to +20V
RESETIN .................................................................-0.3V to +20V
SRT, SWT................................................................-0.3V to +12V
Maximum Current (all pins).................................................30mA
Continuous Power Dissipation (TA = +70°C)
8-Pin µMAX (derate 4.8mW/°C above +70°C) ..........387.8mW
Junction-to-Case Thermal Resistance (θJC) (Note 1) ......42°C/W
Junction-to-Ambient Thermal Resistance (θJA ) (Note 1).....206.3°C/W
Operating Temperature Range (TA) ..................-40°C to +125°C
Junction Temperature (TJ) ...............................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
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
(VIN = 14V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETER
Operating Voltage Range
Supply Current
SWT Ramp Current
SRT Ramp Current
SWT/SRT Ramp Threshold
Voltage
RESET TIMER
Power-On Reset Input Threshold
Voltage
RESETIN Input Leakage Current
RESET Output Low Voltage
RESET Leakage Current
ENABLE Output Low Voltage
ENABLE Leakage Current
Minimum Reset Timeout Period
Reset Timeout Period
Maximum Reset Time Period
RESET to ENABLE Delay
RESETIN to RESET Delay
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
VIN 5.0 40.0 V
IIN
TA = -40°C to +85°C
TA = -40°C to +125°C
18 30
µA
18 60
IRAMP_SWT VSWT = 1.0V
IRAMP_SRT VSRT = 1.0V
450 500 550 nAh t t p : / / w w w . D a t a S h e e t 4 U . n e t /
410 500 600
nA
VRAMP
1.115 1.235 1.363
V
VPON
ILPON
VOLRST
ILKGR
VOLEN
ILKGE
tRESETmin
tRESET
tRESETmax
tREDL
tRRDL
VRESETIN rising
VRESETIN falling
VRESETIN = 2V
RESET asserted, ISINK = 1mA
VIN = 1.1V, ISINK = 160µA, RESET asserted
RESET asserted, ISINK = 0.4mA
VRESET = 20V, RESET not asserted
ENABLE asserted, ISINK = 5mA
VENABLE = 14V, ENABLE not asserted
CSRT = 390pF (Note 3)
CSRT = 2000pF (Note 3)
CSRT = 47nF
RESETIN falling below VPON to RESET
falling edge
1.135
1.115
1.255
1.235
0.1
0.1
0.1
1
5
116.09
1.5
1.383
1.363
0.9
0.4
0.4
0.4
1
V
µA
V
µA
V
µA
ms
ms
ms
µs
µs
2 _______________________________________________________________________________________



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High-Voltage Watchdog Timers with
Adjustable Timeout Delay
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 14V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETER
WATCHDOG TIMER
WDI Input Threshold
WDI Input Hysteresis
WDI Minimum Pulse Width
WDI Input Current
Minimum Watchdog Timeout
Watchdog Timeout Period
Maximum Watchdog Timeout
Watchdog Window
WDI to ENABLE Output Delay
SYMBOL
CONDITIONS
VIH
VIL
WDIHYST
tWDImin
IWDI
tWPmin
tWP
tWPmax
DWDI
(Note 4)
WDI = 0 or 14V
CSWT = 680pF (Note 3)
CSWT = 1200pF (Note 3)
CSWT = 22nF
MAX16998B
MAX16998D
Start from WDI third wrong trigger
MIN TYP MAX UNITS
2.25
6.5
45
67.5
200
0.1
6.8
12
217.36
50
75
100
0.9
55
82.5
V
mV
µs
µA
ms
ms
ms
%tWP
µs
RESET Pullup Resistor Supply
Voltage
(Note 5)
2.25 2.5 18.00
V
ENABLE Pullup Resistor Supply
Voltage
(Note 5)
2.25 2.5 28.00
V
Note
2:
RRESET
and
RENABLE
are
external
pullup
resistors
for
open-drain
http://www.DataSheet4U.net/
outputs.
Connect
RRESET
and
RENABLE
to
a
minimum
2.5V
voltage. Connect RRESET to a maximum voltage of 18V and connect RENABLE to a maximum voltage of 28V.
Note 3: Calculated based on VRAMP = 1.235V and IRAMP = 500nA.
Note 4: WDI pulses narrower than 1µs will be ignored. WDI pulses wider than 6.5µs will be recognized.
Note 5: Not production tested, guaranteed by design.
(CSWT = CSRT = 1500pF, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
10,000
RESET TIMEOUT PERIOD
vs. CSRT
IRAMP = 500nA
1000
100
10
1
10,000
WATCHDOG TIMEOUT PERIOD
vs. CSWT
IRAMP = 500nA
1000
100
10
0.1
0.1
1 10 100
CSRT (nF)
1000
1
0.1
1 10 100
CSWT (nF)
1000
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
26
RESET AND ENABLE NOT
24 ASSERTED
22
20
18
16
14
12
10
0
10 20 30 40
SUPPLY VOLTAGE (V)
50
_______________________________________________________________________________________ 3



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High-Voltage Watchdog Timers with
Adjustable Timeout Delay
Typical Operating Characteristics (continued)
(CSWT = CSRT = 1500pF, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
20.0
19.5 RESET AND ENABLE NOT
ASSERTED
19.0
18.5
18.0
17.5
17.0
16.5
16.0
15.5
15.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
RESETIN TO RESET DELAY
vs. TEMPERATURE
2.00
1.75 RESETIN FROM 2V TO 0V
1.50
1.25 100mV OVERDRIVE
1.00
0.75
50mV OVERDRIVE
0.50
0.25
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
IRAMP
vs. TEMPERATURE
520
515
510
505
500
495
490
485
480
475
470
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
RESETIN/EN THRESHOLD VOLTAGE
vs. TEMPERATURE
1.35
1.33
1.30
1.28 RISING
1.25
1.23
1.20
1.18 FALLING
1.15
1.13
1.10
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
RESETIN/WATCHDOG PERIOD
vs. SUPPLY VOLTAGE
8
7
http://www.DataSheet4U.net/
6 WATCHDOG TIMEOUT
PERIOD (CSWT = 680pF)
5
4
RESET TIMEOUT
3 PERIOD (CSRT = 680pF)
2
1
0
4 8 12 16 20 24 28 32 36 40
SUPPLY VOLTAGE (V)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
RESET OUTPUT VOLTAGE
vs. SINK CURRENT
0.5 1.0 1.5 2.0 2.5
SINK CURRENT (mA)
3.0
RESETIN/EN THRESHOLD VOLTAGE
vs. SUPPLY VOLTAGE
1.50
1.45
1.40
1.35
1.30 RISING
1.25
1.20
1.15 FALLING
1.10
1.05
1.00
4
8 12 16 20 24 28 32 36 40
SUPPLY VOLTAGE (V)
110
100
90
80
70
60
50
40
30
20
10
4
RESETIN/WATCHDOG PERIOD
vs. SUPPLY VOLTAGE
WATCHDOG TIMEOUT
PERIOD (CSWT = 10nF)
RESET TIMEOUT
PERIOD (CSRT = 10nF)
8 12 16 20 24 28 32 36 40
SUPPLY VOLTAGE (V)
ENABLE OUTPUT VOLTAGE
vs. SINK CURRENT
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0 5 10 15 20 25 30
SINK CURRENT (mA)
4 _______________________________________________________________________________________




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