Click here for production status of specific part numbers. MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay General Description The MAX6340/MAX6421-MAX6426 low-power microprocessor supervisor circuits monitor system voltages from 1.6V to 5V. These devices perform a single function: they assert a reset signal whenever the VCC supply voltage falls below its reset threshold. The reset output remains asserted for the reset timeout period after VCC rises above the reset threshold. The reset timeout is externally set by a capacitor to provide more flexibility. Benefits and Features Monitor System Voltages from 1.6V to 5V Capacitor-Adjustable Reset Timeout Period Low Quiescent Current (1.6A typ) Three RESET Output Options Push-Pull RESET Push-Pull RESET Open-Drain RESET The MAX6421/MAX6424 have an active-low, pushpull reset output. The MAX6422 has an active-high, pushpull reset output and the MAX6340/MAX6423/ MAX6425/ MAX6426 have an active-low, open-drain reset output. The MAX6421/MAX6422/MAX6423 are offered in 4-pin SC70 or SOT143 packages. The MAX6340/MAX6424/ MAX6425/MAX6426 are available in 5-pin SOT23-5 packages. Guaranteed Reset Valid to VCC = 1V Immune to Short VCC Transients Applications MAX6426 Pin Compatible with PST92XX Portable Equipment Battery-Powered Computers/Controllers Automotive Medical Equipment Intelligent Instruments Embedded Controllers Critical P Monitoring Set-Top Boxes Computers Pin Configurations TOP VIEW VCC 1 MAX6421X MAX6422X MAX6423X GND 2 4 RESET (RESET) 3 SRT SC70 ( ) ARE FOR THE MAX6422 Pin Configurations continued at end of data sheet. 19-2440; Rev 10; 5/18 Small 4-Pin SC70, 4-Pin SOT143, and 5-Pin SOT23 Packages MAX6340 Pin Compatible with LP3470 MAX6424/MAX6425 Pin Compatible with NCP300-NCP303, MC33464/MC33465, S807/S808/S809, and RN5VD AEC-Q100 Qualified (MAX6340UK31/V+T) Typical Operating Circuit, Selector Guide, and Ordering Information appear at end of data sheet. MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Absolute Maximum Ratings All Voltages Referenced to GND VCC........................................................................-0.3V to +6.0V SRT, RESET, RESET (push-pull).............. -0.3V to (VCC + 0.3V) RESET (open drain)..............................................-0.3V to +6.0V Input Current (all pins).......................................................20mA Output Current (RESET, RESET).....................................20mA Continuous Power Dissipation (TA = +70C) 4-Pin SC70 (derate 3.1mW/C above +70C)..............245mW 4-Pin SOT143 (derate 4mW/C above +70C)............320mW 5-Pin SOT23 (derate 7.1mW/C above +70C)...........571mW Operating Temperature Range.......................... -40C to +125C Storage Temperature Range............................ .-65C to +150C Junction Temperature.......................................................+150C Lead Temperature (soldering, 10s).................................. +300C 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 = 1V to 5.5V, TA = TMIN to TMAX, unless otherwise specified. Typical values are at VCC = 5V and TA = +25C.) (Note 1) PARAMETER Supply Voltage Range Supply Current VCC Reset Threshold Accuracy Hysteresis VCC to Reset Delay Reset Timeout Period VSRT Ramp Current VSRT Ramp Threshold SYMBOL VCC ICC VTH VHYST tRD tRP IRAMP VTH-RAMP RAMP Threshold Hysteresis RESET Output Voltage Low VOL VOH RESET Output Leakage Current, Open-Drain ILKG VOH VOL TYP 1.0 MAX UNITS 5.5 V VCC 5.0V 2.5 4.2 VCC 3.3V 1.9 3.4 VCC 2.0V 1.6 2.5 TA = +25C TA = -40C to +125C VCC falling at 1mV/s CSRT = 1500pF VTH - 1.5% VTH + 1.5% VTH - 2.5% VTH + 2.5% 4 x VTH 80 3.00 4.375 A V mV s 5.75 ms CSRT = 0 0.275 VCC = 1.6V to 5V (VRAMP rising) 0.65 V 33 mV VSRT = 0 to 0.65V; VCC = 1.6V to 5V 240 nA VCC 1.0V, ISINK = 50A 0.3 VCC 4.5V, ISINK = 3.2mA 0.4 VCC 2.7V, ISINK = 1.2mA 0.3 VCC 1.8V, ISOURCE = 200A 0.8 x VCC VCC 4.5V, ISOURCE = 800A 0.8 x VCC VCC 2.25V, ISOURCE = 500A 0.8 x VCC VCC > VTH, reset not asserted 0.8 x VCC VCC 2.7V, ISOURCE = 500A 0.8 x VCC VCC 1.8V, ISOURCE = 150A VCC 1.8V, ISINK = 500A 0.8 x VCC 0.8 x VCC VCC 2.7V, ISINK = 1.2mA VCC 4.5V, ISINK = 3.2mA V V 1.0 VCC 1.0V, ISOURCE = 1A VCC 4.5V, ISOURCE = 800A RESET Output Voltage Low MIN VRAMP falling threshold RESET Output Voltage High, Push-Pull RESET Output Voltage High CONDITIONS A V 0.3 0.3 V 0.4 Note 1: Devices production tested at +25C. Overtemperature limits are guaranteed by design. www.maximintegrated.com Maxim Integrated 2 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Typical Operating Characteristics (VCC = 5V, CSRT = 1500pF, TA = +25C, unless otherwise noted.) 2.0 TA = -40C 1.5 1.0 0.5 0 0 1 2 3 4 5 100 10 1 0.1 0.001 6 0.01 500 400 350 300 200 0 50 25 75 100 125 TEMPERATURE (C) 160 150 0 200 400 600 800 RESET 400s/div 100 140 125 130 120 110 100 80 1000 -50 -25 0 25 75 50 TEMPERATURE (C) 100 125 MAX6421/26 toc08 1.006 NORMALIZED RESET THRESHOLD 1V/div 75 NORMALIZED RESET THRESHOLD vs. TEMPERATURE MAX6421/26 toc07 VTH = 1.6V 50 VCC FALLING AT 1mVs RESET THRESHOLD OVERDRIVE (mV) VCC 25 90 VTH = 2.95V POWER-UP/POWER-DOWN CHARACTERISTIC 1V/div -25 VCC TO RESET DELAY vs. TEMPERATURE (VCC FALLING) RESET OCCURS ABOVE THE CURVE 0 -50 MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE 50 250 0 4.10 1000 100 75 4.15 TEMPERATURE (C) 125 25 -25 100 150 450 -50 10 MAX6421/26 toc05 RESET TIMEOUT PERIOD (s) 550 175 TRANSIENT DURATION (s) CSRT = 0 MAX6421/26 toc04 600 1 4.20 CSRT (nF) SUPPLY VOLTAGE (V) RESET TIMEOUT PERIOD vs. TEMPERATURE 0.1 4.25 MAX6421/26 toc06 TA = +25C 2.5 CSRT = 1500pF RESET TIMEOUT PERIOD (ms) 3.0 1000 VCC TO RESET DELAY Ss) TA = +125C RESET TIMEOUT PERIOD vs. TEMPERATURE 4.30 MAX6421/26 toc02 10,000 RESET TIMEOUT PERIOD (ms) SUPPLY CURRENT (A) 3.5 MAX6421/26 toc01 4.0 RESET TIMEOUT PERIOD vs. CSRT MAX6421/26 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.004 1.002 1.000 0.998 0.996 0.994 -50 -25 0 25 50 75 100 125 TEMPERATURE (C) www.maximintegrated.com Maxim Integrated 3 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Pin Description PIN MAX6340 SOT23 MAX6421 MAX6422 MAX6423 SOT143 SC70 MAX6424 MAX6425 MAX6426 SOT23 SOT23 NAME FUNCTION 1 3 3 5 1 SRT Set Reset Timeout Input. Connect a capacitor between SRT and ground to set the timeout period. Determine the period as follows: tRP = 2.73 x 106 x CSRT + 275s with tRP in seconds and CSRT in farads 2 1 2 3 2, 3 GND Ground 3 -- -- 4 -- N.C. Not Internally Connected. Can be connected to GND 4 2 1 2 5 VCC Supply Voltage and Reset Threshold Monitor Input 5 4 1 4 RESET RESET changes from high to low whenever VCC drops below the selected reset threshold voltage. RESET remains low for the reset timeout period after VCC exceeds the reset threshold -- -- RESET RESET changes from low to high whenever VCC drops below the selected reset threshold voltage. RESET remains high for the reset timeout period after V CC exceeds the reset threshold 4 -- Detailed Description 3.3V Reset Output The reset output is typically connected to the reset input of a P. A P's reset input starts or restarts the P in a known state. The MAX6340/MAX6421-MAX6426 P supervisory circuits provide the reset logic to prevent code-execution errors during power-up, power-down, and brownout conditions (see Typical Operating Characteristics). RESET changes from high to low whenever VCC drops below the threshold voltage. Once VCC exceeds the threshold voltage, RESET remains low for the capacitor-adjustable reset timeout period. The MAX6422 active-high RESET output is the inverse logic of the active-low RESET output. All device outputs are guaranteed valid for VCC > 1V. The MAX6340/MAX6423/MAX6425/MAX6426 are opendrain RESET outputs. Connect an external pullup resistor to any supply from 0 to 5.5V. Select a resistor value large enough to register a logic low when RESET is asserted and small enough to register a logic high while supplying all input current and leakage paths connected to the RESET line. A 10k to 100k pullup is sufficient in most applications. www.maximintegrated.com VCC 5.0V LASER-TRIMMED RESISTORS VREF SRT CSRT RESET TIMEOUT 10k RESET N MAX6340 MAX6423 MAX6425 MAX6426 5V SYSTEM GND Figure 1. MAX6340/MAX6423/MAX6425/MAX6426 Open-Drain RESET Output Allows Use with Multiple Supplies Selecting a Reset Capacitor The reset timeout period is adjustable to accommodate a variety of P applications. Adjust the reset timeout period (tRP) by connecting a capacitor (CSRT) between SRT and ground. Calculate the reset timeout capacitor as follows: Maxim Integrated 4 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay CSRT = (tRP - 275s) / (2.73 5 106) where tRP is in seconds and CSRT is in farads. The reset delay time is set by a current/capacitor-controlled ramp compared to an internal 0.65V reference. An internal 240nA ramp current source charges the external capacitor. The charge to the capacitor is cleared when a reset condition is detected. Once the reset condition is removed, the voltage on the capacitor ramps according to the formula: dV/dt = I/C. The CSRT capacitor must ramp to 0.65V to deassert the reset. CSRT must be a low-leakage (<10nA) type capacitor; ceramic is recommended. Operating as a Voltage Detector The MAX6340/MAX6421-MAX6426 can be operated in a voltage detector mode by floating the SRT pin. The reset delay times for VCC rising above or falling below the threshold are not significantly different. The reset output is deasserted smoothly without false pulses. VCC VDD 10k MAX6340 MAX6423 MAX6425 MAX6426 P RESET N GND OPEN-DRAIN LOGIC N Figure 2. Wired-OR Reset Circuit RESET Applications Information Interfacing to Other Voltages for Logic Compatibility The open-drain outputs of the MAX6340/MAX6423/ MAX6425/MAX6426 can be used to interface to Ps with other logic levels. As shown in Figure 1, the open-drain output can be connected to voltages from 0 to 5.5V. This allows for easy logic compatibility to various Ps. Wired-OR Reset To allow auxiliary circuitry to hold the system in reset, an external open-drain logic signal can be connected to the open-drain RESET of the MAX6340/MAX6423/ MAX6425/MAX6426, as shown in Figure 2. This configuration can reset the P, but does not provide the reset timeout when the external logic signal is released. Negative-Going VCC Transients 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 negative-going transients (glitches). The graph Maximum Transient Duration vs. Reset Threshold Overdrive in the Typical Operating Characteristics shows this relationship. The area below the curve 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 decreases (farther below the reset threshold), the maximum allowable pulse width decreases. Typically, a VCC transient that goes 100mV below the reset threshold and lasts 50s or less does not cause a reset pulse to be issued. Ensuring a Valid RESET or RESET Down to VCC = 0 When VCC falls below 1V, RESET/RESET current-sinking (sourcing) capabilities decline drastically. In the case of the MAX6421/MAX6424, high-impedance CMOS-logic inputs connected to RESET can drift to undetermined voltages. This presents no problems in most applications, since most Ps and other circuitry do not operate with VCC below 1V. In those applications where RESET must be valid down to zero, adding a pulldown resistor between RESET and ground sinks any stray leakage currents, holding RESET low (Figure 3). 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. For applications using the MAX6422, a 100k pullup resis- www.maximintegrated.com Maxim Integrated 5 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Table 1. Reset Threshold Voltage Suffix VCC SUFFIX MIN TYP MAX 16 1.536 1.575 1.614 17 1.623 1.665 1.707 18 1.755 1.800 1.845 19 1.853 1.900 1.948 20 1.950 2.000 2.050 21 2.048 2.100 2.153 22 2.133 2.188 2.243 23 2.255 2.313 2.371 24 2.340 2.400 2.460 25 2.438 2.500 2.563 26 2.559 2.625 2.691 27 2.633 2.700 2.768 28 2.730 2.800 2.870 29 2.852 2.925 2.998 30 2.925 3.000 3.075 31 2.998 3.075 3.152 32 3.120 3.200 3.280 33 3.218 3.300 3.383 34 3.315 3.400 3.485 35 3.413 3.500 3.558 Figure 4. Ensuring RESET Valid to VCC = 0 36 3.510 3.600 3.690 tor between RESET and VCC holds RESET high when VCC falls below 1V (Figure 4). Open-drain RESET versions are not recommended for applications requiring valid logic for VCC down to zero. 37 3.608 3.700 3.793 38 3.705 3.800 3.895 39 3.803 3.900 3.998 40 3.900 4.000 4.100 41 3.998 4.100 4.203 42 4.095 4.200 4.305 43 4.193 4.300 4.408 44 4.266 4.375 4.484 45 4.388 4.500 4.613 46 4.509 4.625 4.741 47 4.583 4.700 4.818 48 4.680 4.800 4.920 49 4.778 4.900 5.023 50 4.875 5.000 5.125 VCC MAX6421 MAX6424 RESET 100k GND Figure 3. Ensuring RESET Valid to VCC = 0 VCC VCC 100k MAX6422 RESET GND Layout Consideration SRT is a precise current source. When developing the layout for the application, be careful to minimize board capacitance and leakage currents around this pin. Traces connected to SRT should be kept as short as possible. Traces carrying high-speed digital signals and traces with large voltage potentials should be routed as far from SRT as possible. Leakage current and stray capacitance (e.g., a scope probe) at this pin could cause errors in the reset timeout period. When evaluating these parts, use clean prototype boards to ensure accurate reset periods. www.maximintegrated.com Maxim Integrated 6 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Standard Versions Table PART* OUTPUT STAGE PART* OUTPUT STAGE MAX6340UK16+T Open-Drain RESET MAX6423US16+T Open-Drain RESET MAX6340UK22+T Open-Drain RESET MAX6423XS16+T Open-Drain RESET MAX6340UK26+T Open-Drain RESET MAX6423US22+T Open-Drain RESET MAX6340UK29+T Open-Drain RESET MAX6423XS22+T Open-Drain RESET MAX6340UK46+T Open-Drain RESET MAX6423US26+T Open-Drain RESET MAX6421US16+T Push-Pull RESET MAX6423XS26+T Open-Drain RESET MAX6421XS16+T Push-Pull RESET MAX6423US29+T Open-Drain RESET MAX6421US22+T Push-Pull RESET MAX6423XS29+T Open-Drain RESET MAX6421XS22+T Push-Pull RESET MAX6423US46+T Open-Drain RESET MAX6421US26+T Push-Pull RESET MAX6423XS46+T Open-Drain RESET MAX6421XS26+T Push-Pull RESET MAX6424UK16+T Push-Pull RESET MAX6421US29+T Push-Pull RESET MAX6424UK22+T Push-Pull RESET MAX6421XS29+T Push-Pull RESET MAX6424UK26+T Push-Pull RESET MAX6421US46+T Push-Pull RESET MAX6424UK29+T Push-Pull RESET MAX6421XS46+T Push-Pull RESET MAX6424UK46+T Push-Pull RESET MAX6422US16+T Push-Pull RESET MAX6425UK16+T Open-Drain RESET MAX6422XS16+T Push-Pull RESET MAX6425UK22+T Open-Drain RESET MAX6422US22+T Push-Pull RESET MAX6425UK26+T Open-Drain RESET MAX6422XS22+T Push-Pull RESET MAX6425UK29+T Open-Drain RESET MAX6422US26+T Push-Pull RESET MAX6425UK46+T Open-Drain RESET MAX6422XS26+T Push-Pull RESET MAX6426UK16+T Open-Drain RESET MAX6422US29+T Push-Pull RESET MAX6426UK22+T Open-Drain RESET MAX6422XS29+T Push-Pull RESET MAX6426UK26+T Open-Drain RESET MAX6422US46+T Push-Pull RESET MAX6426UK29+T Open-Drain RESET MAX6422XS46+T Push-Pull RESET Typical Operating Circuit MAX6426UK46+T Open-Drain RESET *Sample stock is generally held on all standard versions. Contact factory for availability of nonstandard versions. VCC VCC LASER-TRIMMED RESISTORS P VREF SRT CSRT RESET RESET TIMEOUT RESET MAX6421 MAX6424 GND www.maximintegrated.com Maxim Integrated 7 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Pin Configurations (continued) TOP VIEW SRT 1 GND 2 5 RESET RESET MAX6340 N.C. 3 1 VCC 2 4 VCC SRT 4 N.C. 5 VCC 4 RESET MAX6424 MAX6425 GND 3 SOT23 SOT23 GND 1 5 MAX6421U MAX6422U MAX6423U VCC 2 4 RESET (RESET) 3 SRT SOT143 SRT 1 GND 2 MAX6426 GND 3 SOT23 Selector Guide PART PUSH-PULL RESET PUSH-PULL RESET OPEN-DRAIN RESET MAX6340 -- -- 5 SOT23 MAX6421 -- -- 4 SOT143/SC70 MAX6422 -- -- 4 SOT143/SC70 MAX6423 -- -- 4 SOT143/SC70 MAX6424 -- -- 5 SOT23 MAX6425 -- -- 5 SOT23 MAX6426 -- -- 5 SOT23 www.maximintegrated.com PIN-PACKAGE Maxim Integrated 8 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Ordering Information PART Package Information TEMP RANGE PIN-PACKAGE MAX6340UK_ _+T -40C to +125C 5 SOT23-5 MAX6340UK_ _/V+T -40C to +125C 5 SOT23-5 MAX6340UK31/V+T -40C to +125C 5 SOT23-5 MAX6421XS_ _+T -40C to +125C 4 SC70-4 MAX6421US_ _+T -40C to +125C 4 SOT143-4 MAX6421US_ _-T -40C to +125C 4 SOT143-4 MAX6422XS_ _+T -40C to +125C 4 SC70-4 MAX6422US_ _+T -40C to +125C 4 SOT143-4 MAX6422US_ _-T -40C to +125C 4 SOT143-4 MAX6423XS_ _+T -40C to +125C 4 SC70-4 MAX6423US_ _+T -40C to +125C 4 SOT143-4 MAX6423US_ _-T -40C to +125C 4 SOT143-4 MAX6424UK_ _+T -40C to +125C 5 SOT23-5 MAX6424UK_ _-T -40C to +125C 5 SOT23-5 MAX6425UK_ _+T -40C to +125C 5 SOT23-5 MAX6425UK_ _-T -40C to +125C 5 SOT23-5 MAX6426UK_ _+T -40C to +125C 5 SOT23-5 For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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 PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 4 SC70 X4+1 21-0098 90-0187 4 SOT143 U4+1 21-0052 90-0183 5 SOT23 U5+2 21-0057 90-0174 Note: The MAX6340/MAX6421-MAX6426 are available with factory-trimmed reset thresholds from 1.575V to 5.0V in approximately 0.1V increments. Insert the desired nominal reset threshold suffix (from Table 1) into the blanks. There are 50 standard versions with a required order increment of 2500 pieces. Sample stock is generally held on standard versions only (see Standard Versions Table). Required order increment is 10,000 pieces for nonstandard versions. Contact factory for availability. All devices are available in tape-and-reel only. Devices are available in both leaded and lead-free packaging. "+" Denotes Lead(Pb)-free packages and "-" denotes leaded packages. For top mark information, please go to https://www.maximintegrated.com/en/design/packaging/topmark/ Chip Information TRANSISTOR COUNT: 295 PROCESS: BiCMOS www.maximintegrated.com Maxim Integrated 9 MAX6340/MAX6421- MAX6426 Low-Power, SC70/SOT P Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Revision History REVISION NUMBER 5 REVISION DATE PAGES CHANGED DESCRIPTION 3/14 Added /V OPN to Ordering Information 1 6 12/15 Added lead-free part numbers to Ordering Information table and removed top mark information from Standard Versions table 1, 8 7 1/16 Changed MAX6340UK_ _/V-T to MAX6340UK_ _/V+T in Ordering Information table 9 8 9/16 Updated Table 1 6 9 3/18 Updated Ordering Information table 9 10 5/18 Updated Benefits and Features section 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated's website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. (c) 2018 Maxim Integrated Products, Inc. 10