MAX6414UK18+

19-2336; Rev 3; 3/10 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay The MAX6412–MAX6420 low-power microprocessor supervisor circuits monitor system voltages from 1.6V to 5V. These devices are designed to assert a reset signal whenever the VCC supply voltage or RESET IN falls below its reset threshold or the manual reset input is asserted. The reset output remains asserted for the reset timeout period after VCC and RESET IN rise above the reset threshold and the manual reset input is deasserted. The reset timeout is externally set by a capacitor to provide more flexibility. The MAX6412/MAX6413/MAX6414 feature fixed thresholds from 1.575V to 5V in approximately 100mV increments and a manual reset input. The MAX6415/MAX6416/MAX6417 are offered with an adjustable reset input that can monitor voltages down to 1.26V and the MAX6418/MAX6419/ MAX6420 are offered with one fixed input and one adjustable input to monitor dual-voltage systems. The MAX6412/MAX6415/MAX6418 have an active-low, push-pull reset output. The MAX6413/MAX6416/ MAX6419 have an active-high, push-pull reset output and the MAX6414/MAX6417/MAX6420 have an activelow, open-drain reset output. All of these devices are offered in a SOT23-5 package and are fully specified from -40°C to +125°C. Features o Monitor System Voltages from 1.6V to 5V o Capacitor-Adjustable Reset Timeout Period o Manual Reset Input (MAX6412/MAX6413/MAX6414) o Adjustable Reset Input Option (MAX6415–MAX6420) o Dual-Voltage Monitoring (MAX6418/MAX6419/MAX6420) o Low Quiescent Current (1.7µA, typ) o 3 RESET Output Options Push-Pull RESET Push-Pull RESET Open-Drain RESET o Guaranteed Reset Valid to VCC = 1V o Power-Supply Transient Immunity o Small SOT23-5 Packages Ordering Information PART TEMP RANGE MAX6412UK_ _-T -40°C to +125°C 5 SOT23 MAX6413UK_ _-T -40°C to +125°C 5 SOT23 Automotive MAX6414UK_ _-T -40°C to +125°C 5 SOT23 Medical Equipment MAX6415UK-T -40°C to +125°C 5 SOT23 Intelligent Instruments MAX6416UK-T -40°C to +125°C 5 SOT23 Portable Equipment MAX6417UK-T -40°C to +125°C 5 SOT23 Battery-Powered Computers/Controllers MAX6418UK_ _-T -40°C to +125°C 5 SOT23 Embedded Controllers MAX6419UK_ _-T -40°C to +125°C 5 SOT23 Critical µP Monitoring MAX6420UK_ _-T -40°C to +125°C 5 SOT23 Applications Set-Top Boxes Computers Pin Configuration TOP VIEW RESET/RESET 1 GND 2 5 VCC 4 SRT MAX6412– MAX6420 RESET IN (MR) 3 SOT23-5 ( ) FOR THE MAX6412/MAX6413/MAX6414. PIN-PACKAGE Note: The MAX6412/MAX6413/MAX6414 and MAX6418/ MAX6419/MAX6420 are available with factory-set VCC 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 following the letters UK. There are 33 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. Typical Operating Circuit appears at end of data sheet. Selector Guide appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX6412–MAX6420 General Description MAX6412–MAX6420 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay ABSOLUTE MAXIMUM RATINGS All Voltages Referenced to GND VCC ........................................................................-0.3V to +6.0V SRT, MR, RESET IN ....................................-0.3V to (VCC + 0.3V) 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 = +70°C) 5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Soldering Temperature (reflow) .......................................+260°C 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 SYMBOL Supply Voltage Range VCC Supply Current ICC VCC Reset Threshold Accuracy Hysteresis Reset Timeout Period tRP 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 2 ILKG VOH UNITS 5.5 V 2.6 4.5 2 3.5 VCC ≤ 2.0V 1.7 2.5 TA = +25°C VTH 1.25% VTH + 1.25% TA = -40°C to +125°C VTH 2.5% VTH + 2.5% µA V VCC falling at 1mV/µs CSRT = 1500pF 3.00 CSRT = 0 4 x VTH mV 100 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 ≤ 3.3V VRAMP falling threshold VOL TYP VCC ≤ 5.0V VHYST tRD VSRT Ramp Threshold MIN 1.0 VTH VCC to Reset Delay VSRT Ramp Current CONDITIONS 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 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay (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 SYMBOL RESET Output Voltage LOW VOL CONDITIONS MIN TYP MAX VCC ≥ 1.8V, ISINK = 500µA 0.3 VCC ≥ 2.7V, ISINK = 1.2mA 0.3 VCC ≥ 4.5V, ISINK = 3.2mA 0.4 RESET IN Leakage Current UNITS V 10 RESET IN Threshold VRST VRST falling, VCC = 1.6V to 5.0V VIL VIL V 2.4 V 0.3 x VCC VCC < 4.0V VIH nA 1.255 0.8 VCC > 4.0V VIH MR Input 1.205 0.7 x VCC MR Minimum Pulse Width 1 µs MR Glitch Rejection 75 MR to RESET Delay ns 20 MR Pullup Resistance Pull up to VCC 12 ns 20 28 kΩ Note 1: Devices production tested at TA = +25°C. Over temperature limits are guaranteed by design. Typical Operating Characteristics (VCC = 5V, CSRT = 1500pF, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. TEMPERATURE TA = +25°C 2 TA = -40°C 1 VCC = 5V 2.5 VCC = 3.3V 2.0 VCC = 1.8V 1.5 1.0 VCC = 1V 10,000 RESET TIMEOUT PERIOD (ms) 3 3.0 MAX6412-20 toc02 SUPPLY CURRENT (µA) TA = +125°C RESET TIMEOUT PERIOD vs. CSRT 3.5 SUPPLY CURRENT (µA) MAX6412-20 toc01 4 MAX6412-20 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE 1000 100 10 1 0.5 0 0 0 1 2 3 4 SUPPLY VOLTAGE (V) 5 6 -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125 0.1 0.001 0.01 0.1 1 10 100 1000 CSRT (nF) _______________________________________________________________________________________ 3 MAX6412–MAX6420 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VCC = 5V, CSRT = 1500pF, TA = +25°C, unless otherwise noted.) RESET TIMEOUT PERIOD vs. TEMPERATURE 4.25 4.20 4.15 4.10 600 CSRT = 0 550 RESET TIMEOUT PERIOD (µs) CSRT = 1500pF 500 MAX6412-20 toc05 RESET TIMEOUT PERIOD vs. TEMPERATURE MAX6412-20 toc04 RESET TIMEOUT PERIOD (ms) 4.30 450 400 350 300 250 200 4.05 -50 -25 0 25 50 75 100 -50 125 -25 TEMPERATURE (°C) RESET IN THRESHOLD VOLTAGE vs. TEMPERATURE 25 75 50 TEMPERATURE (°C) 100 1.270 1.265 1.260 125 MAX6412-20 toc07 175 150 TRANSIENT DURATION (µs) 1.275 0 MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE MAX6412-20 toc06 1.280 RESET IN THRESHOLD VOLTAGE (V) MAX6412–MAX6420 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay 125 100 RESET OCCURS ABOVE THE CURVE 75 50 1.255 25 1.250 0 VTH = 3.0V -50 -25 0 25 50 75 TEMPERATURE (°C) 4 100 125 0 200 400 600 800 RESET THRESHOLD OVERDRIVE (mV) _______________________________________________________________________________________ 1000 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay PIN MAX6412/ MAX6413/ MAX6414 1 2 MAX6415/ MAX6416/ MAX6417 1 2 MAX6418/ MAX6419/ MAX6420 NAME RESET RESET changes from high to low whenever VCC or RESET IN drops below the selected reset threshold voltage (VTH or VRESET IN, respectively) or manual reset is pulled low. RESET remains low for the reset timeout period after all reset conditions are deasserted and then goes high. RESET RESET changes from low to high whenever the VCC or RESET IN drops below the selected reset threshold voltage (VTH or VRESET IN) or manual reset is pulled low. RESET remains high for the reset timeout period after all reset conditions are deasserted and then goes low. 1 2 FUNCTION GND Ground Reset Input. High-impedance input to the adjustable reset comparator. Connect RESET IN to the center point of an external resistor-divider network to set the threshold of the externally monitored voltage. See Reset Threshold section. — 3 3 RESET IN 3 — — MR Manual Reset Input. Pull this pin low to manually reset the device. Reset remains asserted for the reset timeout period after MR is released. 4 4 4 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) ✕ CSRT + 275µs with tRP in seconds and CSRT in Farads. 5 5 5 VCC Supply Voltage and Input for Fixed-Threshold VCC Monitor Detailed Description The MAX6412–MAX6420 low-power microprocessor (µP) supervisory circuits provide maximum adjustability for supply-voltage monitoring and reset functionality. In addition, the MAX6412–MAX6420 reset timeout period is adjustable using an external capacitor. The MAX6412/MAX6413/MAX6414 have factorytrimmed reset threshold voltages in approximately 100mV increments from 1.575V to 5.0V with a manual reset input. The MAX6415/MAX6416/MAX6417 contain a reset threshold that can be adjusted to any voltage above 1.26V using external resistors. The MAX6418/ MAX6419/MAX6420 offer both a factory-trimmed reset threshold and an adjustable reset threshold input for dual-voltage monitoring. A reset signal is asserted when VCC and/or RESET IN falls below the preset values or when MR is asserted. The reset remains asserted for an externally programmed interval after VCC and/or RESET IN has risen above the reset threshold or MR is deasserted. 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 MAX6412–MAX6420 µP supervisory circuits provide the reset logic to prevent codeexecution errors during power-up, power-down, and brownout conditions (see Typical Operating Circuit). For the MAX6413, MAX6416, and MAX6419, RESET changes from low to high whenever VCC or RESET IN drops below the reset threshold voltages. Once RESET IN and VCC exceed their respective reset threshold voltage(s), RESET remains high for the reset timeout period, then goes low. On power-up, once VCC reaches 1V, RESET is guaranteed to be a logic high. For applications requiring valid reset logic when VCC is less than 1V, see the section Ensuring a Valid RESET/RESET Output Down to VCC = 0V. The active-low RESET output of the remaining supervisors is the inverse of the MAX6413, MAX6416, and MAX6419 active-high RESET output and is guaranteed valid for VCC ≥ 1V. _______________________________________________________________________________________ 5 MAX6412–MAX6420 Pin Description MAX6412–MAX6420 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay Reset Threshold VCC The MAX6415–MAX6420 monitor the voltage on RESET IN with an external resistor voltage-divider (Figure 1). Use the following formula to calculate the externally monitored voltage (VMON_TH): VMON_TH = VRST  (R1 + R2)/R2 where VMON_TH is the desired reset threshold voltage and VRST is the reset input threshold (1.26V). 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 (1MΩ, for example) and calculate R1 based on the desired monitored voltage, using the following formula: R1 = R2 x (VMON_TH/VRST - 1) (Ω) R1 RESET IN VCC R2 GND MAX6415– MAX6420 SRT Manual Reset Input (MAX6412/MAX6413/MAX6414) Many µP-based products require manual reset capability, allowing the operator, a technician, or external logic circuitry to initiate a reset. A logic low on MR asserts reset. Reset remains asserted while MR is low and for the reset timeout period after MR returns high. The MR has an internal 20kΩ pullup resistor so it can be left open if not used. Connect a normally open momentary switch from MR to ground to create a manual reset function (external debounce circuitry is not required for long reset timeout periods). A manual reset option can easily be implemented with the MAX6415–MAX6420 by connecting a normally open momentary switch in parallel with R2 (Figure 2). When the switch is closed, the voltage on RESET IN goes to zero, VMON_TH Figure 2. Adding an External Manual Reset Function to the MAX6415–MAX6420 initiating a reset. Similar to the MAX6412/MAX6413/ MAX6414 manual reset, reset remains asserted while the switch is closed and for the reset timeout period after the switch is opened. Monitoring Voltages Other than VCC (MAX6415/MAX6416/MAX6417) The MAX6415/MAX6416/MAX6417 contain an adjustable reset threshold input. These devices can be used to VMON_TH VCC R1 R1 RESET IN RESET IN VCC VCC R2 R2 GND MAX6415 MAX6416 MAX6417 GND MAX6415 MAX6416 MAX6417 SRT SRT VMON_TH = 1.26 x (R1 + R2)/R2 Figure 1. Calculating the Monitored Threshold Voltage (VMON_TH) 6 Figure 3. Monitoring External Voltages _______________________________________________________________________________________ Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay MAX6412–MAX6420 VMON_TH VCC MAX6420 ONLY VCC LASER-TRIMMED RESISTORS RL RESET CIRCUITRY 1.26V (RESET) RESET µP R1 R2 RESET IN GND SRT MAX6418 MAX6419 MAX6420 CSRT Figure 4. MAX6418/MAX6419/MAX6420 Monitoring Two Voltages monitor voltages other than VCC. Calculate VMON_TH as shown in the Reset Threshold section. (See Figure 3.) Dual-Voltage Monitoring (MAX6418/MAX6419/MAX6420) The MAX6418/MAX6419/MAX6420 contain both factory-trimmed threshold voltages and an adjustable reset threshold input, allowing the monitoring of two voltages, VCC and VMON_TH (see Figure 4). Reset is asserted when either of the voltages falls below its respective threshold voltage. Application Information 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 _______________________________________________________________________________________ 7 MAX6412–MAX6420 Low-Power, Single/Dual-Voltage µP Reset Circuits with Capacitor-Adjustable Reset Timeout Delay 5.0V 3.3V VCC 10kΩ RESET 5V SYSTEM MAX6414 MAX6417 MAX6420 GND Reset Threshold Overdrive graph 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 negativegoing 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 50µs or less will not cause a reset pulse to be issued. Ensuring a Valid RESET or RESET Down to VCC = 0V Figure 5. MAX6414/MAX6417/MAX6420 Open-Drain RESET Output Allows use with Multiple Supplies 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 (