19-0344; Rev 3; 3/98 3-Pin Microprocessor Reset Circuits The MAX809/MAX810 are microprocessor (µP) supervisory circuits used to monitor the power supplies in µP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5V-powered or 3Vpowered circuits. These circuits perform a single function: They assert a reset signal whenever the VCC supply voltage declines below a preset threshold, keeping it asserted for at least 140ms after VCC has risen above the reset threshold. The only difference between the two devices is that the MAX809 has an active-low RESET output (which is guaranteed to be in the correct state for V CC down to 1V), while the MAX810 has an active-high RESET output. The reset comparator is designed to ignore fast transients on VCC. Reset thresholds suitable for operation with a variety of supply voltages are available. Low supply current makes the MAX809/MAX810 ideal for use in portable equipment. The MAX809/MAX810 come in a 3-pin SOT23 package. ________________________Applications Computers Controllers ____________________________Features ♦ Precision Monitoring of 3V, 3.3V, and 5V Power-Supply Voltages ♦ Fully Specified Over Temperature ♦ 140ms Min Power-On Reset Pulse Width RESET Output (MAX809) RESET Output (MAX810) ♦ 17µA Supply Current ♦ Guaranteed RESET Valid to VCC = 1V (MAX809) ♦ Power Supply Transient Immunity ♦ No External Components ♦ 3-Pin SOT23 Package Ordering Information PART† MAX809_EUR-T MAX809_EUR-T10 Portable/Battery-Powered Equipment Automotive PIN-PACKAGE 3 SOT23-3 3 SOT23-3 Ordering Information continued at end of data sheet. Note: These parts are offered in 2.5k or 10k reels, and must be ordered in 2.5k or 10k increments. Order MAX809_EUR-T for 2.5k reels and MAX809_EUR-T10 for 10k reels. †Insert the desired suffix letter (from the table below) into the blank to complete the part number: SOT TOP MARK MAX809 MAX810 AAAA AGAA SUFFIX RESET THRESHOLD (V) L 4.63 M 4.38 ABAA J* 4.00 CWAA — T 3.08 ACAA AJAA S 2.93 ADAA AKAA R 2.63 AFAA ALAA Intelligent Instruments Critical µP and µC Power Monitoring TEMP. RANGE -40°C to +105°C -40°C to +105°C AHAA * J version is available for MAX809 only. __________Typical Operating Circuit __________________Pin Configuration TOP VIEW VCC µP MAX809 RESET GND GND 1 VCC VCC MAX809 MAX810 RESET INPUT GND 3 VCC RESET (RESET) 2 SOT23-3 ( ) ARE FOR MAX810. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX809J/L/M/R/S/T, MAX810L/M/R/S/T General Description MAX809J/L/M/R/S/T, MAX810L/M/R/S/T 3-Pin Microprocessor Reset Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC ........................................................................-0.3V to 6.0V RESET, RESET..........................................-0.3V to (VCC + 0.3V) Input Current, VCC ..............................................................20mA Output Current, RESET, RESET ..........................................20mA Rate of Rise, VCC.......................................................................100V/µs Continuous Power Dissipation (TA = +70°C) SOT23 (derate above +70°C by 4mW/°C) ...................320mW Operating Temperature Range .........................-40°C to +105°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°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 = full range, TA = -40°C to +105°C, unless otherwise noted. Typical values are at TA = +25°C, VCC = 5V for L/M/J versions, VCC = 3.3V for T/S versions, and VCC = 3V for R version.) (Note 1) PARAMETER SYMBOL VCC Range Supply Current CONDITIONS 1.0 5.5 1.2 5.5 TA = -40°C to +85°C VCC < 5.5V, MAX8_ _ L/M 24 VCC < 3.6V, MAX8_ _ R/S/T 17 TA = +85°C to +105°C VCC < 5.5V, MAX8_ _ L/M 100 VCC < 3.6V, MAX8_ _ R/S/T 100 ICC MAX809J VTH MAX8_ _T MAX8_ _S MAX8_ _R 4.63 50 4.56 TA = -40°C to +85°C 4.50 TA = +85°C to +105°C 4.40 TA = +25°C 4.31 TA = -40°C to +85°C 4.25 TA = +85°C to +105°C 4.16 TA = +25°C 3.93 TA = -40°C to +85°C 3.89 TA = +85°C to +105°C 3.80 TA = +25°C 3.04 TA = -40°C to +85°C 3.00 TA = +85°C to +105°C 2.92 TA = +25°C 2.89 TA = -40°C to +85°C 2.85 TA = +85°C to +105°C 2.78 TA = +25°C 2.59 TA = -40°C to +85°C 2.55 2.70 TA = +85°C to +105°C 2.50 2.76 VCC = VTH to (VTH - 100mV) Reset Active Timeout Period VOL 140 TA = +85°C to +105°C 100 µA 4.75 4.86 4.38 4.45 4.50 4.56 4.00 4.06 4.10 4.20 3.08 3.11 V 3.15 3.23 2.93 2.96 3.00 3.08 2.63 2.66 ppm/°C 20 TA = -40°C to +85°C V 4.70 30 VCC to Reset Delay (Note 2) UNITS 60 TA = +25°C Reset Threshold Tempco 2 MAX TA = -40°C to +105°C MAX8_ _M RESET Output Voltage Low (MAX809) TYP TA = 0°C to +70°C MAX8_ _L Reset Threshold (Note 2) MIN 240 µs 560 840 VCC = VTH min, ISINK = 1.2mA, MAX809R/S/T 0.3 VCC = VTH min, ISINK = 3.2mA, MAX809L/M 0.4 VCC > 1.0V, ISINK = 50µA 0.3 _______________________________________________________________________________________ ms V 3-Pin Microprocessor Reset Circuits (VCC = full range, TA = -40°C to +105°C, unless otherwise noted. Typical values are at TA = +25°C, VCC = 5V for L/M/J versions, VCC = 3.3V for T/S versions, and VCC = 3V for R version.) (Note 1) PARAMETER SYMBOL RESET Output Voltage High (MAX809) VOH RESET Output Voltage Low (MAX810) VOL RESET Output Voltage High (MAX810) VOH CONDITIONS MIN TYP VCC > VTH max, ISOURCE = 500µA, MAX809R/S/T 0.8VCC VCC > VTH max, ISOURCE = 800µA, MAX809L/M VCC - 1.5 MAX UNITS V VCC = VTH max, ISINK = 1.2mA, MAX810R/S/T 0.3 VCC = VTH max, ISINK = 3.2mA, MAX810L/M 0.4 1.8V < VCC < VTH min, ISOURCE = 150µA V 0.8VCC V Note 1: Production testing done at TA = +25°C, over temperature limits guaranteed by design only. Note 2: RESET Output for MAX809, RESET Output for MAX810. __________________________________________Typical Operating Characteristics VCC = 3V 15 10 5 25 VCC = 3V 15 10 VCC = 1V 0 0 -20 0 20 40 60 85 VOD = 10mV 80 60 VOD = 20mV 40 VOD = 100mV 20 VOD = 200mV 0 -40 -20 0 20 40 60 85 TEMPERATURE (°C) TEMPERATURE (°C) POWER-DOWN RESET DELAY vs. TEMPERATURE (MAX8_ _L/M) POWER-UP RESET TIMEOUT vs. TEMPERATURE NORMALIZED RESET THRESHOLD vs. TEMPERATURE 100 VOD = 20mV 80 60 40 VOD = 100mV 20 VOD = 200mV 0 -20 20 0 40 TEMPERATURE (°C) 60 245 MAX8_ _L/M 240 MAX8_ _R/S/T 235 230 85 1.002 1.001 1.000 0.999 0.998 0.997 225 85 60 MAX809/10-TOC6 VOD = 10mV -20 1.003 MAX809/10-TOC5 120 250 -40 NORMALIZED THRESHOLD VOD = VTH - VCC POWER-UP RESET TIMEOUT (ms) 140 -40 VOD = VTH - VCC 20 0 40 TEMPERATURE (°C) MAX809/10-TOC4 -40 POWER-DOWN RESET DELAY (µs) 20 5 VCC = 1V POWER-DOWN RESET DELAY (µs) 25 20 VCC = 5V SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 30 100 MAX809/10-TOC2 VCC = 5V POWER-DOWN RESET DELAY vs. TEMPERATURE (MAX8_ _R/S/T) 30 MAX809/10-TOC1 35 SUPPLY CURRENT vs. TEMPERATURE (NO LOAD, MAX8_ _L/M) MAX809/10-TOC3 SUPPLY CURRENT vs. TEMPERATURE (NO LOAD, MAX8_ _R/S/T) -40 -20 0 20 40 TEMPERATURE (°C) 60 85 -40 -20 0 20 40 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX809J/L/M/R/S/T, MAX810L/M/R/S/T ELECTRICAL CHARACTERISTICS (continued) _____________________Pin Description PIN NAME 1 GND Ground RESET (MAX809) RESET Output remains low while VCC is below the reset threshold, and for 240ms after VCC rises above the reset threshold. RESET (MAX810) RESET Output remains high while VCC is below the reset threshold, and for 240ms after VCC rises above the reset threshold. 2 3 VCC 400 FUNCTION MAXIMUM TRANSIENT DURATION (µs) MAX809J/L/M/R/S/T, MAX810L/M/R/S/T 3-Pin Microprocessor Reset Circuits TA = +25°C 320 240 160 MAX8_ _L/M 80 MAX8_ _R/S/T Supply Voltage (+5V, +3.3V, or +3.0V) 0 1 __________Applications Information Negative-Going VCC Transients In addition to issuing a reset to the microprocessor (µP) during power-up, power-down, and brownout conditions, the MAX809/MAX810 are relatively immune to short duration negative-going VCC transients (glitches). Figure 1 shows typical transient duration vs. reset comparator overdrive, for which the MAX809/MAX810 do not generate a reset pulse. The graph was generated using a negative-going pulse applied to VCC, starting 0.5V above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). The graph indicates the maximum pulse width a negative-going VCC transient can have without causing a reset pulse. As the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. Typically, for the MAX809L and MAX810M, a VCC transient that goes 100mV below the reset threshold and lasts 20µs or less will not cause a reset pulse. A 0.1µF bypass capacitor mounted as close as possible to the VCC pin provides additional transient immunity. 4 10 100 1000 RESET COMPARATOR OVERDRIVE , VTH - VCC (mV) Figure 1. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive Ensuring a Valid Reset Output Down to VCC = 0V When VCC falls below 1V, the MAX809 RESET output no longer sinks current—it becomes an open circuit. Therefore, high-impedance CMOS logic inputs connected to RESET can drift to undetermined voltages. This presents no problem in most applications, since most µP and other circuitry is inoperative with VCC below 1V. However, in applications where RESET must be valid down to 0V, adding a pull-down resistor to RESET causes any stray leakage currents to flow to ground, holding RESET low (Figure 2). R1’s value is not critical; 100kΩ is large enough not to load RESET and small enough to pull RESET to ground. A 100kΩ pull-up resistor to VCC is also recommended for the MAX810, if RESET is required to remain valid for VCC < 1V. _______________________________________________________________________________________ 3-Pin Microprocessor Reset Circuits VCC BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC VCC MAX809 RESET RESET GND µP 4.7k MAX809 RESET R1 100k GND Figure 2. RESET Valid to VCC = Ground Circuit Interfacing to µPs with Bidirectional Reset Pins µPs with bidirectional reset pins (such as the Motorola 68HC11 series) can connect to the MAX809 reset output. If, for example, the MAX809 RESET output is asserted high and the µP wants to pull it low, indeterminate logic levels may result. To correct this, connect a 4.7kΩ resistor between the MAX809 RESET output and the µP reset I/O (Figure 3). Buffer the MAX809 RESET output to other system components. Benefits of Highly Accurate Reset Threshold Most µP supervisor ICs have reset threshold voltages between 5% and 10% below the value of nominal supply voltages. This ensures a reset will not occur within 5% of the nominal supply, but will occur when the supply is 10% below nominal. When using ICs rated at only the nominal supply ±5%, this leaves a zone of uncertainty where the supply is between 5% and 10% low, and where the reset may or may not be asserted. The MAX809L/T and MAX810L/T use highly accurate circuitry to ensure that reset is asserted close to the 5% limit, and long before the supply has declined to 10% below nominal. GND Figure 3. Interfacing to µPs with Bidirectional Reset I/O ___________________Chip Information TRANSISTOR COUNT: 275 Ordering Information (continued) PART† MAX810_EUR-T MAX810_EUR-T10 TEMP. RANGE -40°C to +105°C -40°C to +105°C PIN-PACKAGE 3 SOT23-3 3 SOT23-3 Note: These parts are offered in 2.5k or 10k reels, and must be ordered in 2.5k or 10k increments. Order MAX809_EUR-T for 2.5k reels and MAX809_EUR-T10 for 10k reels. †Insert the desired suffix letter (from the table below) into the blank to complete the part number: SUFFIX RESET THRESHOLD (V) SOT TOP MARK MAX809 MAX810 AAAA AGAA L 4.63 M 4.38 ABAA J* 4.00 CWAA — T 3.08 ACAA AJAA S 2.93 ADAA AKAA R 2.63 AFAA ALAA AHAA * J version is available for MAX809 only. _______________________________________________________________________________________ 5 MAX809J/L/M/R/S/T, MAX810L/M/R/S/T BUFFER ________________________________________________________Package Information SOTPO3L.EPS MAX809J/L/M/R/S/T, MAX810L/M/R/S/T 3-Pin Microprocessor Reset Circuits 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. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.