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MAX6730UTRD3-MAX6731UTTD3+-MAX6735KATGD3+T
Single-/Dual-/Triple-Voltage µP Supervisory Circuits with Independent Watchdog Output
General DescriptionThe MAX6730–MAX6735 single/dual/triple-voltage micro-processor (μP) supervisors feature a watchdog timer and manual reset capability. The MAX6730–MAX6735 offer factory-set reset thresholds for monitoring voltages from +0.9V to +5V and an adjustable reset input for monitoring voltages down to +0.63V. The combination of these features significantly improves system reliability and accuracy when
compared to separate ICs or discrete components.
The active-low reset output asserts and remains asserted for the reset timeout period after all the monitored voltages exceed their respective thresholds. Multiple factory-set reset threshold combinations reduce the number of external
components required. The MAX6730/MAX6731 monitor a single fixed voltage, the MAX6732/MAX6733 monitor two fixed voltages, and the MAX6734/MAX6735 monitor two fixed voltages and one adjustable voltage. All devices are offered with six minimum reset timeout periods ranging from 1.1ms to 1120ms.
The MAX6730–MAX6735 feature a watchdog timer with an independent watchdog output. The watchdog timer
prevents system lockup during code execution errors. A watchdog startup delay of 54s after reset asserts allows system initialization during power-up. The watchdog operates in normal mode with a 1.68s delay after initialization. The MAX6730/MAX6732/MAX6734 provide an active-low, open-drain watchdog output. The MAX6731/MAX6733/MAX6735 provide an active-low, push-pull watchdog
output.
Other features include a manual reset input (MAX6730/MAX6731/MAX6734/MAX6735) and push-pull reset output (MAX6731/MAX6733/MAX6735) or open-drain reset output (MAX6730/MAX6732/MAX6734). The MAX6730–MAX6733 are offered in a tiny SOT23-6 package. The MAX6734/MAX6735 are offered in a space-saving SOT23-8 package. All devices are fully specified over the extended -40°C to +85°C temperature range.
Applications●Multivoltage Systems●Telecom/Networking Equipment●Computers/Servers●Portable/Battery-Operated Equipment●Industrial Equipment●Printer/Fax●Set-Top Boxes
Beneits and Features●VCC1 (Primary Supply) Reset Threshold Voltages from +1.575V to +4.63V●VCC2 (Secondary Supply) Reset Threshold Voltages from +0.79V to +3.08V●Adjustable RSTIN Threshold for Monitoring Voltages Down to +0.63V (MAX6734/MAX6735 Only)●Six Reset Timeout Options●Watchdog Timer with Independent Watchdog Output • 35s (min) Initial Watchdog Startup Period • 1.12s (min) Normal Watchdog Timeout Period●Manual Reset Input (MAX6730/MAX6731/MAX6734/MAX6735)●Guaranteed Reset Valid down to
VCC1 or VCC2 = +0.8V●Push-Pull RESET or Open-Drain RESET Output●Immune to Short VCC Transients●Low Supply Current: 14μA (typ) at +3.6V●Small 6-Pin and 8-Pin SOT23 Packages
Pin Configurations appear at end of data sheet.
MAX6734
MAX6735+0.9V
VCORE+3.3V
+1.8V
GND
RSTINRST
WDI
WDOPUSHBUTTON
SWITCH
RESET
NMI
I/O
VCC
(I/O)
VDD
(MEMORY)
VCC1VCC2
GND
Typical Operating Circuit
MAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
VCC1, VCC2, RSTIN, MR, WDI to GND ..................-0.3V to +6V
RST, WDO to GND (open drain) .............................-0.3V to +6V
RST, WDO to GND (push-pull) ..............-0.3V to (VCC1 + 0.3V)Input Current/Output Current (all pins) ...............................20mAContinuous Power Dissipation (TA = +70°C) 6-Pin SOT23-6 (derate 4.3mW/°C above +70°C) ....347.8mW 8-Pin SOT23-8 (derate 5.6mW/°C above +70°C) ....444.4mW
Operating Temperature Range ...........................-40°C to +85°CStorage Temperature Range ............................-65°C to +150°C
Junction Temperature ......................................................+150°CLead Temperature (soldering, 10s) .................................+300°CSoldering Temperature (reflow) Lead (Pb)-free packages.............................................+260°C Package containing lead (Pb) .....................................+240°C
6 SOT23 Junction-to-Ambient Thermal Resistance (θJA) ........230°C/W Junction-to-Case Thermal Resistance (θJC) ...............76°C/W
8 SOT23 Junction-to-Ambient Thermal Resistance (θJA) ........180°C/W Junction-to-Case Thermal Resistance (θJC) ...............60°C/W
(Note 1)(VCC1 = VCC2 = +0.8V to +5.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSupply VoltageVCC1,
VCC20.85.5V
Supply Current
ICC1
VCC1 < +5.5V, all I/O connections open, outputs not asserted1539
VCC1 < +3.6V, all I/O connections open, outputs not asserted1028
ICC2
VCC2 < +3.6V, all I/O connections open, outputs not asserted411
VCC2 < +2.75V, all I/O connections open, outputs not asserted39
VCC1 Reset ThresholdVTH1
L (falling)4.5004.6254.750
M (falling)4.2504.3754.500
T (falling) 3.0003.0753.150
S (falling)2.8502.9253.000
R (falling)2.5502.6252.700
Z (falling)2.2502.3132.375
Y (falling)2.1252.1882.250
W (falling)1.6201.6651.710
V (falling)1.5301.5751.620
MAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
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.maximintegrated.com/thermal-tutorial.
Absolute Maximum RatingsStresses 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.
Package Thermal Characteristics
Electrical Characteristics
(VCC1 = VCC2 = +0.8V to +5.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSVCC2 Reset ThresholdVTH2
T (falling) 3.0003.0753.150
S (falling)2.8502.9253.000
R (falling)2.5502.6252.700
Z (falling)2.2502.3132.375
Y (falling)2.1252.1882.250
W (falling)1.6201.6651.710
V (falling)1.5301.5751.620
I (falling)1.3501.3881.425
H (falling)1.2751.3131.350
G (falling)1.0801.1101.140
F (falling)1.0201.0501.080
E (falling)0.8100.8330.855
D (falling)0.7650.7880.810
Reset Threshold Tempco20ppm/°C
Reset Threshold HysteresisVHYSTReferenced to VTH typical0.5%
VCC_ to RST Output DelaytRD
VCC1 = (VTH1 + 100mV) to
(VTH1 - 100mV) or
VCC2 = (VTH2 + 75mV) to
(VTH2 - 75mV)µs
Reset Timeout PeriodtRP1.11.652.28.813.217.61402102802804205605608401120112016802240
ADJUSTABLE RESET COMPARATOR INPUT (MAX6734/MAX6735)RSTIN Input ThresholdVRSTIN611626.5642mV
RSTIN Input CurrentIRSTIN-25+25nA
RSTIN Hysteresis3mV
RSTIN to Reset Output DelaytRSTINDVRSTIN to (VRSTIN - 30mV)22µs
MANUAL RESET INPUT (MAX6730/MAX6731/MAX6734/MAX6735)MR Input ThresholdVIL0.3 x VCC1VVIH0.7 x VCC1
MR Minimum Pulse Width1µs
MR Glitch Rejection100ns
MR to Reset Output DelaytMR200ns
MR Pullup Resistance255080kΩ
MAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
Electrical Characteristics (continued)
(VCC1 = VCC2 = +0.8V to +5.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2)
Note 2: Devices tested at TA = +25°C. Overtemperature limits are guaranteed by design and not production tested.
Note 3: Parameter guaranteed by design.
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
WATCHDOG INPUTWatchdog Timeout Period
tWD-LFirst watchdog period after reset
timeout period355472
tWD-SNormal mode1.121.682.24
WDI Pulse WidthtWDI(Note 3)50ns
WDI Input Voltage
VIL0.3 x VCC1VIH0.7 x VCC1
WDI Input CurrentIWDIWDI = 0 or VCC1-1+1µA
RESET/WATCHDOG OUTPUTRST/WDO Output Low Voltage (Push-Pull or Open Drain)VOL
VCC1 or VCC2 ≥ +0.8V,
ISINK = 1µA, output asserted0.3
VCC1 or VCC2 ≥ +1.0V,
ISINK = 50µA, output asserted0.3
VCC1 or VCC2 ≥ +1.2V,
ISINK = 100µA, output asserted0.3
VCC1 or VCC2 ≥ +2.7V,
ISINK = 1.2mA, output asserted0.3
VCC1 or VCC2 ≥ +4.5V,
ISINK = 3.2mA, output asserted0.4
RST/WDO Output High Voltage (Push-Pull Only)VOH
VCC1 ≥ +1.8V, ISOURCE = 200µA,
output not asserted0.8 x VCC1VCC1 ≥ +2.7V, ISOURCE = 500µA,
output not asserted0.8 x VCC1
VCC1 ≥ +4.5V, ISOURCE = 800µA,
output not asserted0.8 x VCC1
RST/WDO Output Open-Drain
Leakage CurrentOutput not asserted0.5µA
MAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
Electrical Characteristics (continued)
(VCC1 = +5V, VCC2 = +3.3V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +3.3V, VCC2 = +2.5V)
MAX6730-35 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
TOTAL
ICC1
ICC2
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +2.5V, VCC2 = +1.8V)
MAX6730-35 toc03
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
TOTAL
ICC1
ICC2
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +1.8V, VCC2 = +1.2V)
MAX6730-35 toc04
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
TOTAL
ICC1
ICC2
NORMALIZED THRESHOLD VOLTAGE
vs. TEMPERATUREMAX6730-35 toc05
TEMPERATURE (°C)
NORMALIZED THRESHOLD VOLTAGE3510-15
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +5V, VCC2 = +3.3V)
MAX6730-35 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
TOTAL
ICC1
ICC2
MAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
Typical Operating Characteristics
(VCC1 = +5V, VCC2 = +3.3V, TA = +25°C, unless otherwise noted.)
NORMALIZED TIMEOUT PERIOD
vs. TEMPERATUREMAX6730-35 toc06
TEMPERATURE (°C)
NORMALIZED TIMEOUT PERIOD3510-15
MAXIMUM VCC_ TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6730-35 toc07
RESET THRESHOLD OVERDRIVE (mV)
MAXIMUM V
CC_
TRANSIENT DURATION (ms)100
10,0001000
RST ASSERTS
ABOVE THIS LINE
MR TO RESET OUTPUT DELAYMAX6730-35 toc08
40ns/div
MR
2V/div
RST
2V/div
VCC_ TO RESET OUTPUT DELAY
vs. TEMPERATURE (100mV OVERDRIVE)MAX6730-35 toc09
TEMPERATURE (°C)
CC_
TO RESET OUTPUT DELAY (µs)35-1510
RSTIN TO RESET OUTPUT DELAY
vs. TEMPERATURE
MAX6730-35 toc10
TEMPERATURE (°C)
RSTIN TO RESET OUTPUT DELAY (µs)35-1510-4585
MAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
Typical Operating Characteristics (continued)
PIN
NAMEFUNCTIONMAX6730
MAX6731
MAX6732
MAX6733
MAX6734 MAX673511RST
Active-Low Reset Output. The MAX6730/MAX6732/MAX6734 provide an open-drain
output. The MAX6731/MAX6733/MAX6735 provide a push-pull output. RST asserts low when any of the following conditions occur: VCC1 or VCC2 drops below its preset threshold, RSTIN drops below its reset threshold, or MR is driven low. Open-
drain versions require an external pullup resistor.22GNDGround34WDO
Active-Low Watchdog Output. The MAX6730/MAX6732/MAX6734 provide an
open-drain WDO output. The MAX6731/MAX6733/MAX6735 provide a push-pull
WDO output. WDO asserts low when no low-to-high or high-to-low transition occurs on WDI within the watchdog timeout period (tWD) or if an undervoltage lockout condition exists for VCC1, VCC2, or RSTIN. WDO deasserts without a timeout period when VCC1, VCC2, and RSTIN exceed their reset thresholds, or when the manual
reset input is asserted. Open-drain versions require an external pullup resistor.—5MR
Active-Low Manual Reset Input. Drive MR low to force a reset. RST remains
asserted as long as MR is low and for the reset timeout period after MR releases
high. MR has a 50kΩ pullup resistor to VCC1; leave MR open or connect to VCC1 if
unused.53WDI
Watchdog Input. If WDI remains high or low for longer than the watchdog timeout period, the internal watchdog timer expires and the watchdog output asserts low. The internal watchdog timer clears whenever RST asserts or a rising or falling edge on WDI is detected. The watchdog has an initial watchdog timeout period (35s min) after each reset event and a short timeout period (1.12s min) after the irst valid WDI transition. Leaving WDI unconnected does not disable the watchdog timer function.68VCC1Primary Supply-Voltage Input. VCC1 provides power to the device when it is greater
than VCC2. VCC1 is the input to the primary reset threshold monitor.46VCC2Secondary Supply-Voltage Input. VCC2 provides power to the device when it is
greater than VCC1. VCC2 is the input to the secondary reset threshold monitor.—7RSTIN
Undervoltage Reset Comparator Input. RSTIN provides a high-impedance comparator input for the adjustable reset monitor. RST asserts low if the voltage at RSTIN drops below the 626mV internal reference voltage. Connect a resistive voltage-divider to RSTIN to monitor voltages higher than 626mV. Connect RSTIN to
GNDWDO
VCC1WDI
RST
MAX6730
MAX6731
SOT23-6TOP VIEW4
GND
VCC2WDO6VCC1WDI
RST
MAX6732
MAX6733
SOT23-6SOT23-84
VCC2WDO
VCC1
RSTINGND
WDI
RST
MAX6734
MAX6735+
Pin ConigurationsMAX6730–MAX6735Single/Dual/Triple-Voltage μP SupervisoryCircuits with Independent Watchdog Output
Pin Description
