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19-2637; Rev 3; 6/10
P Supervisors with Separate VCC Reset and Manual Reset Outputs
General Description
The MAX6453-MAX6456 are low-power, dual-voltage P supervisors featuring separate VCC reset and manual reset outputs. The dual outputs support both softsystem reset (interrupt) and hard-system reset (reboot) functions. The reset output asserts when any of the monitored voltages falls below its specified threshold and remains asserted for the reset timeout (140ms min) after all voltages exceed their respective reset thresholds. All devices are offered with nine factory-fixed reset thresholds for monitoring primary system voltages (VCC) from 1.8V to 5V and an adjustable reset input for monitoring a secondary system voltage down to 0.63V. Each device has a manual reset input, a VCC reset output, and a manual reset output. The MAX6453/ MAX6454 manual reset output asserts when the manual reset input is low. It remains asserted for the manual reset timeout period (140ms min) after the manual reset input transitions high. The MAX6453/MAX6354 manual reset input controls only the manual reset output and does not affect the VCC reset output. The manual reset input of the MAX6455/MAX6456 controls both the manual reset and VCC reset outputs. When the manual reset input is low for less than the extended setup timeout period, only the manual reset output asserts and remains asserted for the manual reset timeout period (140ms min) after the manual reset input transitions high. If the manual reset input is low for at least the extended setup timeout period, the reset output also asserts and remains asserted for the reset timeout period (140ms min) after the manual reset input transitions high. This enhanced feature allows the implementation of a soft/hard-system reset combination. The MAX6453/MAX6455 have active-low, push-pull reset and manual reset outputs, and the MAX6454/ MAX6456 have active-low, open-drain reset and manual reset outputs. All devices are available in small SOT23-6 packages and are fully specified over the extended temperature range (-40C to +85C).
Features
Precision Factory-Set Reset Thresholds From 1.6V to 4.6V Adjustable Threshold to Monitor Voltages Down to 0.63V Manual Reset Input with Extended Setup Period Immune to Short Voltage Transients Low 6A Supply Current Guaranteed Valid Reset Down to VCC = 1.0V Active-Low RESET (Push-Pull or Open-Drain) Outputs 140ms (min) Reset Timeout Period Small SOT Package
MAX6453-MAX6456
Ordering Information
PART MAX6453UT_ _ _-T MAX6454UT_ _ _-T MAX6455UT_ _ _-T MAX6456UT_ _ _-T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 6 SOT23 6 SOT23 6 SOT23 6 SOT23
Note: The first "_ _" is a placeholder for the threshold voltage level of the devices. A desired threshold level is set by the part number suffix found in Table 1. The third "_" is a placeholder for the manual reset setup period of the devices. A desired setup period is set by the letter suffix found in Table 2. All devices are available in tape-and-reel only. There is a 2500-piece minimum order increment for standard versions (Table 2). Sample stock is typically held on standard versions only. Nonstandard versions require a minimum order increment of 10,000 pieces. Contact factory for availability. Devices are available in both leaded and lead(Pb)-free packaging. Specify lead-free by replacing "-T" with "+T" when ordering. Selector Guide appears at end of data sheet.
Pin Configurations
TOP VIEW
RESET 1 6 MR RESET 1 6 MR
Applications
Set-Top Boxes Consumer Electronics DVD Players Cable/DSL Modems MP3 Players Industrial Equipment Automotive Medical Devices
SOT23-6 SOT23-6
MROUT 3 4 VCC MROUT 3 4 VCC GND 2
MAX6453 MAX6454
5
RSTIN
GND 2
MAX6455 MAX6456
5
RSTIN
________________________________________________________________ Maxim Integrated Products
1
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P Supervisors with Separate VCC Reset and Manual Reset Outputs MAX6453-MAX6456
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND) VCC ..........................................................................-0.3V to +6V Open-Drain RESET, MROUT ....................................-0.3V to +6V MR, Push-Pull RESET, MROUT ..................-0.3V to (VCC + 0.3V) MR, RSTIN ...............................................................-0.3V to +6V Input Current, All Pins.......................................................20mA Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C).............696mW Operating Temperature Range .......................... -40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Soldering Temperature (reflow) Lead(Pb)-free...............................................................+260C Containing Lead...........................................................+240C
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
(VCC = 1.0V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER Operating Voltage Range VCC Supply Current SYMBOL VCC ICC VCC = 5.5V, no load VCC = 3.6V, no load 46 44 31 29 VCC Reset Threshold VTH 26 23 22 17 16 Reset Threshold Tempco Reset Threshold Hysteresis RSTIN Threshold RSTIN Threshold Hysteresis RSTIN Input Current RSTIN to Reset Output Delay Reset Timeout Period VCC to RESET Output Delay MR Minimum Setup Period (Pulse Width) MR Minimum Input Pulse MR Glitch Rejection MR to MROUT Delay Manual Reset Timeout Period tMRP 140 tRP tRD VCC falling at 1mV/s K tMR MR to RESET L S T RESET asserted, MAX6455/MAX6456 6.72 4.48 2.24 1.12 2.24 VTH-RSTIN VHYST IRSTIN VRSTIN falling at 1mV/s 140 -25 15 210 20 10.08 6.72 3.36 1.68 3.36 100 200 210 280 13.44 8.16 4.48 2.24 4.48 s ns ns ms s 280 TA = 0C to +85C TA = -40C to +85C 0.615 0.610 2.5 +25 4.50 4.25 3.00 2.85 2.55 2.25 2.12 1.62 1.52 CONDITIONS MIN 1.0 7 6 4.63 4.38 3.08 2.93 2.63 2.32 2.19 1.67 1.58 60 2 x VTH 0.630 0.645 0.650 TYP MAX 5.5 20 16 4.75 4.50 3.15 3.00 2.70 2.38 2.25 1.71 1.62 ppm/C mV V mV nA s ms s V UNITS V A
2
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P Supervisors with Separate VCC Reset and Manual Reset Outputs
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 1.0V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER MR to VCC Pullup Impedance VCC 1.00V, ISINK = 50A, outputs asserted RESET, MROUT Output Low (Open Drain or Push-Pull) VCC 1.20V, ISINK = 100A, outputs asserted VOL VCC 2.55V, ISINK = 1.2mA, outputs asserted VCC 4.25V, ISINK = 3.2mA, outputs asserted VCC 1.80V, ISOURCE = 200A, outputs deasserted RESET, MROUT Output High (Push-Pull) VOH VCC 3.15V, ISOURCE = 500A, outputs deasserted VCC 4.75V, ISOURCE = 800A, outputs deasserted RESET, MROUT Output Open-Drain Leakage Current MR Input Low Voltage MR Input High Voltage ILKG VIL VIH 0.7 x VCC Outputs deasserted 0.8 x VCC 0.8 x VCC 0.8 x VCC 1 0.3 x VCC A V V V SYMBOL CONDITIONS MIN 25 TYP 50 MAX 75 0.3 0.3 V 0.3 0.4 UNITS k
MAX6453-MAX6456
Note 1: Devices production tested at TA = 25C. Overtemperature limits are guaranteed by design.
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P Supervisors with Separate VCC Reset and Manual Reset Outputs MAX6453-MAX6456
Typical Operating Characteristics
(VCC = 3.3V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX6453 toc01
NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE
1.04 NORMALIZED TIMEOUT PERIOD 1.03 1.02 1.01 1.00 0.99 0.98 0.97 0.96 0.95 0 -40 -15 10 35 60 85 0
MAX6453 toc02
MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE
MAX6453 toc03
9 8 SUPPLY CURRENT (A) 7 6 5 4 3 2 1 0 TA = -40C TA = +25C TA = +85C
1.05
250
TRANSIENT DURATION (s)
200
150
RESET OCCURS ABOVE THE CURVE
100
50 VTH = 4.4V 200 400 600 800 1000
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
TEMPERATURE (C)
RESET THRESHOLD OVERDRIVE (mV)
NORMALIZED VCC RESET THRESHOLD vs. TEMPERATURE
MAX6453 toc04
VCC TO RESET DELAY vs. TEMPERATURE
MAX6453 toc05
RSTIN TO RESET DELAY vs. TEMPERATURE (RSTIN FALLING)
23.6 RSTIN TO RESET DELAY (s) 23.2 22.8 22.4 22.0 21.6 21.2 20.8 20.4 20.0 RSTIN FALLING AT 1mV/s
MAX6453 toc06
1.03 NORMALIZED VCC RESET THRESHOLD 1.02 1.01 1.00 0.99 0.98 0.97 -40 -15 10 35 60
24.0 23.6 VCC TO RESET DELAY (s) 23.2 22.8 22.4 22.0 21.6 21.2 20.8 20.4 20.0 VCC FALLING AT 1mV/s
24.0
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
MANUAL RESET TO MROUT AND RESET DELAY (MAX6455/MAX6456)
MAX6453 toc07
VCC TO RESET DELAY
MAX6453 toc08
VCC = 5V MR (5V/div) VCC = 4.5V VTH = 4.392V VCC = 4.3V
MROUT (5V/div)
VCC (100mV/div)
RESET (5V/div)
RESET (2V/div) TIME (1s/div) TIME (100s/div)
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P Supervisors with Separate VCC Reset and Manual Reset Outputs
Pin Description
PIN MAX6453 MAX6454 MAX6455 MAX6456 NAME FUNCTION Active-Low Push-Pull or Open-Drain Output. RESET changes from high to low when VCC or RSTIN drops below its selected reset threshold. RESET remains low for the 140ms (min) reset timeout period after all monitored power-supply inputs exceed their selected reset thresholds. MR does not affect RESET output. For open-drain outputs, connect to an external pullup resistor. RESET Active-Low Push-Pull or Open-Drain Output. RESET changes from high to low when VCC or RSTIN drops below its selected reset threshold. RESET remains low for the 140ms (min) reset timeout period after all monitored power-supply inputs exceed their selected reset thresholds. RESET changes from high to low after MR input is held low for the extended (typ) setup timeout period and deasserts 140ms (min) after MR deasserts. For open-drain outputs, connect to an external pullup resistor. Ground Manual Reset Push-Pull or Open-Drain Output. MROUT asserts immediately after MR is pulled low. MROUT remains low for 140ms (min) after MR is deasserted. For opendrain outputs, connect to an external pullup resistor. VCC Voltage Input. Power supply and input for the primary microprocessor voltage reset monitor. Reset Input. High-impedance input to the adjustable reset comparator. Connect RSTIN to the center point of an external resistor divider to set the threshold of the externally monitored voltage. Manual Reset Input. Internal 50k pullup to VCC. Pull MR low to immediately assert MROUT. MR does not affect RESET output. MR -- 6 Manual Reset Input. Internal 50k pullup to VCC. Pull MR low to immediately assert MROUT. RESET changes from high to low after MR input is held low for the extended (typ) setup timeout period.
MAX6453-MAX6456
1
--
--
1
2 3
2 3
GND MROUT
4
4
VCC
5
5
RSTIN
6
--
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P Supervisors with Separate VCC Reset and Manual Reset Outputs MAX6453-MAX6456
Manual Reset The MAX6453/MAX6454 contain a manual reset output (MROUT) that asserts low immediately after driving MR low and remains low for the reset timeout period after MR goes high (Figure 1). The pushbutton manual reset has no effect on the RESET output. MROUT output can be used to drive an NMI (nonmaskable interrupt) on the processor to save valuable data. The MAX6455/MAX6456's MROUT is asserted immediately upon driving MR low. Driving MR low for longer than the extended (typ) setup timeout period asserts RESET. When MR is deasserted, MROUT and RESET remain asserted low for the reset timeout period after MR goes high (Figure 2).
MR 210ms
MROUT
Figure 1. MAX6453/MAX6454 Timing Diagram
Detailed Description
Reset Output
The reset output is typically connected to the reset input of a microprocessor (P). A P's reset input starts or restarts the P in a known state. The MAX6453- MAX6456 P supervisory circuits provide the reset logic to prevent code-execution errors during powerup, power-down and brownout conditions (see the Typical Operating Circuit). RESET changes from high to low whenever the monitored voltage (RSTIN or VCC) drops below the reset threshold voltages. When VRSTIN and VCC exceed their respective reset threshold voltages, RESET remains low for the reset timeout period, and then goes high. RESET changes from high to low after MR input is held low for the extended (typ) setup timeout period and deasserts 140ms (min) after MR deasserts. RESET is guaranteed to be in the proper output logic state for VCC inputs 1V. For applications requiring valid reset logic when VCC is less than 1V, see the Ensuring a Valid RESET Output Down to VCC = 0V section.
Adjustable Input Voltage (RSTIN)
The MAX6453-MAX6456 monitor the voltage on RSTIN using an adjustable reset threshold set with an external resistor voltage divider (Figure 3). Use the following formula to calculate the externally monitored voltage (VMON-TH): VMON-TH = VTH-RSTIN (R1 +R2)/R2 where VMON_TH is the desired reset threshold voltage and V TH-RSTIN is the reset input threshold (0.63V). Resistors R1 and R2 can have very high values to minimize current consumption due to low leakage currents. Set R2 to some conveniently high value (250k, for example) and calculate R1 based on the desired reset threshold voltage, using the following formula: R1 = R2 (VMON_TH/VTH - 1)
LONG SETUP PERIOD
MR 210ms MROUT
RESET
Figure 2. MAX6455/MAX6456 Timing Diagram
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P Supervisors with Separate VCC Reset and Manual Reset Outputs
VMON_TH VCC
R1
MAX6453 MAX6455
RSTIN VCC
R2 GND RESET
Generally, the pullup resistor connected to the RESET connects to the supply voltage being monitored at the IC's VCC pin. However, some systems might use the open-drain output to level-shift from the monitored supply to reset circuitry powered by some other supply (Figure 5). Keep in mind that as the supervisor's VCC decreases toward 1V, so does the IC's ability to sink current at RESET (RESET is pulled high as VCC decays toward 0). The voltage where this occurs depends on the pullup resistor value and the voltage to which it is connected.
MAX6453-MAX6456
Ensuring a Valid RESET Down to VCC = 0V (Push-Pull RESET)
When VCC falls below 1V, RESET current-sinking capabilities decline drastically. The high-impedance CMOSlogic inputs connected to RESET can drift to undetermined voltages. This presents no problem in most applications, because most Ps and other circuitry do not operate with VCC below 1V. In applications where RESET must be valid down to 0V, add a pulldown resistor between RESET and GND for the push/pull outputs. The resistor sinks any stray leakage currents, holding RESET low (Figure 6). The value of the pulldown resistor is not critical; 100k is large enough not to load RESET and small enough to pull RESET to ground. The external pulldown cannot be used with the open-drain reset outputs.
VMON_TH = 0.63 x (R1 + R2) / R2
Figure 3. Calculating The Monitored Threshold Voltages
Applications Information
Interrupt Before Reset
To minimize data loss and speed system recovery/test, many applications interrupt the processor or reset only portions of the system before a processor hard reset is asserted. The extended setup time of the MAX6455/ MAX6456 MR input allows the same pushbutton (Figure 4) to control both the interrupt and hard reset functions. If the pushbutton is closed for less than the extended setup timeout period, the processor is only interrupted (MROUT). If the system still does not respond properly, the pushbutton can be closed for the full extended setup timeout period to hard reset the processor (RESET). If desired, connect a LED to the RESET output to turn off (or on) to signify when the pushbutton is closed long enough for a hard reset (the same LED can be used as the front panel power-on display).
Transient Immunity
In addition to issuing a reset to the P during power-up, power-down and brownout conditions, these supervisors are relatively immune to short duration falling transients (glitches). The graph Maximum Transient Duration vs. Reset Threshold Overdrive in the Typical Operating Characteristics section shows this relationship. The area below the curves of the graph is the region in which these devices typically do not generate a reset pulse. This graph was generated using a negative going pulse applied to VCC, starting above the actual reset threshold (VTH) and ending below it by the magnitude indicated (reset-threshold overdrive). As the magnitude of the transient increases (V CC goes further below the reset threshold), the maximum allowable pulse width decreases. Typically, a VCC transient that goes 100mV below the reset threshold and lasts 20s or less does not cause a reset pulse to be issued.
Interfacing to Other Voltages for Logic Compatibility
The open-drain RESET output can be used to interface to a P with other logic levels. As shown in Figure 5, the open-drain output can be connected to voltages from 0 to 6V.
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P Supervisors with Separate VCC Reset and Manual Reset Outputs MAX6453-MAX6456
+3.3V +1.5V CORE SUPPLY VCC RESET RESET I/O SUPPLY
5V
3.3V
VCC
VCC
MAX6455
RSTIN LED
P
MAX6454 MAX6456
RESET
100k
P
GND
MROUT MR
NMI
RESET GND
GND
PUSHBUTTON SWITCH CLOSE FOR IMMEDIATE SYSTEM INTERRUPT CLOSE FOR >3.36s FOR SYSTEM RESET
Figure 4. Interrupt Before Reset Application Circuit
Figure 5. Interfacing to Other Voltage Levels
Functional Diagram
VCC
VCC VCC
MAX6453- MAX6456
MAX6453 MAX6455
RESET 100k GND
RSTIN
RESET TIMOUT PERIOD (210ms typ)
RESET
VCC 0.63V 1.23V
MR-TO-RESET SETUP PERIOD (3.36s typ) MAX6455/MAX6456
MROUT TIMOUT PERIOD (210ms typ) VCC GND MR
MROUT
Figure 6. Ensuring RESET Valid to VCC = 0
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P Supervisors with Separate VCC Reset and Manual Reset Outputs
Table 1. Reset Voltage Threshold
PART NO. SUFFIX (__) 46 44 31 29 26 23 22 17 16 VCC NOMINAL VOLTAGE THRESHOLD (V) 4.625 4.375 3.075 2.925 2.625 2.313 2.188 1.665 1.575
Table 3. Standard Versions Table
PART MAX6453UT16S MAX6453UT23S MAX6453UT26S MAX6453UT29S MAX6453UT46S MAX6454UT16S MAX6454UT23S MAX6454UT26S MAX6454UT29S MAX6454UT46S TOP MARK ABOG ABOH ABOI ABOJ ABOK ABOP ABEQ ABOQ ABOR ABOS PART MAX6455UT16S MAX6455UT23S MAX6455UT26S MAX6455UT29S MAX6455UT46S MAX6456UT16S MAX6456UT23S MAX6456UT26S MAX6456UT29S MAX6456UT46S TOP MARK ABOL ABOM ABON ABOO ABER ABES ABOT ABOU ABOV ABOW
MAX6453-MAX6456
Table 2. Manual Reset Setup Period
PART NO. SUFFIX (_) K L S T MANUAL RESET PERIOD (s) 10.08 6.72 3.36 1.68
Selector Guide
PART MAX6453 MAX6454 MAX6455 MAX6456 MR TO RESET DELAY -- -- MR ASSERTION MROUT MROUT MROUT and RESET MROUT and RESET MROUT AND RESET PUSH-PULL OUTPUT -- -- MROUT AND RESET OPEN-DRAIN OUTPUT -- --
Typical Operating Circuit
+3.3V +1.5V CORE SUPPLY VCC RSTIN RESET RESET I/O SUPPLY
P MAX6453
MROUT NMI GND
MR
GND
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P Supervisors with Separate VCC Reset and Manual Reset Outputs MAX6453-MAX6456
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 6 SOT23 PACKAGE CODE U6-1 DOCUMENT LAND NO. PATTERN NO. 21-0058 90-0175
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P Supervisors with Separate VCC Reset and Manual Reset Outputs
Revision History
REVISION NUMBER 0 REVISION DATE 10/02 Initial release Revised the General Description, Features, Applications, Ordering Information, Absolute Maximum Ratings, Electrical Characteristics, Pin Description, the Reset Output, Manual Reset, and Interrupt Before Reset sections, and Tables 2 and 3 to add extended setup time specifications. DESCRIPTION PAGES CHANGED --
MAX6453-MAX6456
3
6/10
1, 2, 5, 6, 7, 9
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
11 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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