MAX6421US26-T

MAX6340/ MAX6421–MAX6426 Low-Power, SC70/SOT µP 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. The MAX6421/MAX6424 have an active-low, pushpull reset output. The MAX6422 has an active-high, push-pull 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. Features o Monitor System Voltages from 1.6V to 5V o Capacitor-Adjustable Reset Timeout Period o Low Quiescent Current (1.6µA typ) o Three RESET Output Options Push-Pull RESET Push-Pull RESET Open-Drain RESET o Guaranteed Reset Valid to VCC = 1V o Immune to Short VCC Transients o Small 4-Pin SC70, 4-Pin SOT143, and 5-Pin SOT23 Packages o MAX6340 Pin Compatible with LP3470 o MAX6424/MAX6425 Pin Compatible with NCP300–NCP303, MC33464/MC33465, S807/S808/S809, and RN5VD o MAX6426 Pin Compatible with PST92XX Applications Portable Equipment Battery-Powered Computers/Controllers Ordering Information PART TEMP RANGE PIN-PACKAGE MAX6340UK_ _-T -40°C to +125°C 5 SOT23-5 Automotive MAX6340UK_ _/V+T -40°C to +125°C 5 SOT23-5 Medical Equipment MAX6421XS_ _-T -40°C to +125°C 4 SC70-4 Intelligent Instruments MAX6421US_ _-T -40°C to +125°C 4 SOT143-4 Embedded Controllers MAX6422XS_ _-T -40°C to +125°C 4 SC70-4 Critical µP Monitoring MAX6422US_ _-T -40°C to +125°C 4 SOT143-4 MAX6423XS_ _-T -40°C to +125°C 4 SC70-4 MAX6423US_ _-T -40°C to +125°C 4 SOT143-4 MAX6424UK_ _-T -40°C to +125°C 5 SOT23-5 MAX6425UK_ _-T -40°C to +125°C 5 SOT23-5 MAX6426UK_ _-T -40°C to +125°C 5 SOT23-5 Set-Top Boxes Computers Typical Operating Circuit appears at end of data sheet. Pin Configurations TOP VIEW + VCC 1 GND 2 MAX6421X MAX6422X MAX6423X 4 RESET (RESET) 3 SRT SC70 ( ) ARE FOR THE MAX6422 Pin Configurations continued at end of data sheet. 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. Specify lead-free by replacing "-T" with "+T" when ordering. /V denotes an automotive qualified part. Typical Operating Circuit appears at end of data sheet. Selector Guide appears at end of data sheet. For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com. 19-2440; Rev 5; 12/13 MAX6340/ MAX6421–MAX6426 Low-Power, SC70/SOT µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 4-Pin SC70 (derate 3.1mW/°C above +70°C) ..............245mW 4-Pin SOT143 (derate 4mW/°C above +70°C).............320mW 5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW Operating Temperature Range .........................-40°C to +125°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C 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 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 = +25°C.) (Note 1) PARAMETER Supply Voltage Range Supply Current VCC Reset Threshold Accuracy Hysteresis SYMBOL ICC VTH tRD Reset Timeout Period tRP VSRT Ramp Threshold IRAMP VTH-RAMP RAMP Threshold Hysteresis RESET Output Voltage Low RESET Output Voltage High, Push-Pull RESET Output Leakage Current, Open-Drain RESET Output Voltage High RESET Output Voltage Low MIN ILKG VOH VOL UNITS 5.5 V 2.5 4.2 VCC ≤ 3.3V 1.9 3.4 VCC ≤ 2.0V 1.6 2.5 TA = +25°C VTH - 1.5% VTH + 1.5% TA = -40°C to +125°C VTH - 2.5% VTH + 2.5% VCC falling at 1mV/µs CSRT = 1500pF 3.00 CSRT = 0 µA V 4 x VTH mV 80 µs 4.375 5.75 0.275 ms VSRT = 0 to 0.65V; VCC = 1.6V to 5V 240 VCC = 1.6V to 5V (VRAMP rising) 0.65 V 33 mV nA VCC ≥ 1.0V, ISINK = 50µA 0.3 VCC ≥ 2.7V, ISINK = 1.2mA 0.3 VCC ≥ 4.5V, ISINK = 3.2mA 0.4 VCC ≥ 1.8V, ISOURCE = 200µA VOH MAX VCC ≤ 5.0V VRAMP falling threshold VOL TYP 1.0 VHYST VCC to Reset Delay VSRT Ramp Current CONDITIONS VCC V 0.8 x VCC VCC ≥ 2.25V, ISOURCE = 500µA 0.8 x VCC VCC ≥ 4.5V, ISOURCE = 800µA 0.8 x VCC VCC > VTH, reset not asserted V 1.0 VCC ≥ 1.0V, ISOURCE = 1µA 0.8 x VCC VCC ≥ 1.8V, ISOURCE = 150µA 0.8 x VCC VCC ≥ 2.7V, ISOURCE = 500µA 0.8 x VCC VCC ≥ 4.5V, ISOURCE = 800µA 0.8 x VCC µA V VCC ≥ 1.8V, ISINK = 500µA 0.3 VCC ≥ 2.7V, ISINK = 1.2mA 0.3 VCC ≥ 4.5V, ISINK = 3.2mA 0.4 V Note 1: Devices production tested at +25°C. Overtemperature limits are guaranteed by design. 2 Maxim Integrated MAX6340/ MAX6421–MAX6426 Low-Power, SC70/SOT µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Typical Operating Characteristics (VCC = 5V, CSRT = 1500pF, TA = +25°C, unless otherwise noted.) TA = +25°C 2.5 2.0 TA = -40°C 1.5 1.0 1000 100 10 1 4.30 CSRT = 1500pF RESET TIMEOUT PERIOD (ms) 3.0 MAX6421/26 toc02 TA = +125°C 10,000 RESET TIMEOUT PERIOD (ms) SUPPLY CURRENT (μA) MAX6421/26 toc01 4.0 3.5 RESET TIMEOUT PERIOD vs. TEMPERATURE RESET TIMEOUT PERIOD vs. CSRT 4.25 MAX6421/26 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE 4.20 4.15 0.5 0 1 2 3 4 5 4.10 0.01 0.1 1 10 -50 1000 100 0 25 50 75 100 CSRT (nF) TEMPERATURE (°C) RESET TIMEOUT PERIOD vs. TEMPERATURE MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE VCC TO RESET DELAY vs. TEMPERATURE (VCC FALLING) 450 400 350 300 125 100 RESET OCCURS ABOVE THE CURVE 75 50 250 25 200 0 VCC FALLING AT 1mVμs 150 0 50 25 75 100 125 140 130 120 110 100 90 VTH = 2.95V -25 80 0 TEMPERATURE (°C) 200 400 600 800 1000 -50 -25 0 RESET THRESHOLD OVERDRIVE (mV) POWER-UP/POWER-DOWN CHARACTERISTIC 1V/div RESET 1V/div 100 125 MAX6421/26 toc08 1.006 NORMALIZED RESET THRESHOLD VCC 25 75 50 TEMPERATURE (°C) NORMALIZED RESET THRESHOLD vs. TEMPERATURE MAX6421/26 toc07 VTH = 1.6V 125 MAX6421/26 toc06 150 160 VCC TO RESET DELAY (μs) 500 MAX6421/26 toc05 550 175 TRANSIENT DURATION (μs) CSRT = 0 -50 -25 SUPPLY VOLTAGE (V) 600 RESET TIMEOUT PERIOD (μs) 0.1 0.001 6 MAX6421/26 toc04 0 1.004 1.002 1.000 0.998 0.996 0.994 400μs/div -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) Maxim Integrated 3 MAX6340/ MAX6421–MAX6426 Low-Power, SC70/SOT µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Pin Description PIN MAX6340 SOT23 1 MAX6421 MAX6422 MAX6423 SOT143 3 SC70 3 MAX6424 MAX6425 MAX6426 SOT23 SOT23 NAME 5 1 SRT FUNCTION Set Reset Timeout Input. Connect a capacitor between SRT and ground to set the timeout period. Determine the period as follows: tRP = 2.73 ✕ 106 ✕ CSRT + 275µs 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 1 4 — 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 VCC exceeds the reset threshold. 4 — — Detailed Description Reset Output The reset output is typically connected to the reset input of a µP. A µP’s reset input starts or restarts the µP in a known state. The MAX6340/MAX6421–MAX6426 µP 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 capacitoradjustable 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 10kΩ to 100kΩ pullup is sufficient in most applications. 4 3.3V VCC LASER-TRIMMED RESISTORS 5.0V 10kΩ VREF RESET 5V SYSTEM SRT N RESET TIMEOUT CSRT MAX6340 MAX6423 MAX6425 MAX6426 GND Figure 1. MAX6340/MAX6423/MAX6425/MAX6426 Open-Drain RESET Output Allows Use with Multiple Supplies Maxim Integrated MAX6340/ MAX6421–MAX6426 Low-Power, SC70/SOT µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Selecting a Reset Capacitor The reset timeout period is adjustable to accommodate a variety of µP applications. Adjust the reset timeout period (tRP) by connecting a capacitor (CSRT) between SRT and ground. Calculate the reset timeout capacitor as follows: CSRT = (tRP - 275µs) / (2.73  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 (