19-1933 Rev 2; 12/05 3-Pin, Low-Power µP Reset Circuits The MAX6800/MAX6801/MAX6802 microprocessor (µP) supervisory circuits monitor the power supplies in 2.85V to 5.0V µP and digital systems. They increase circuit reliability and reduce cost by eliminating external components and adjustments. These devices perform a single function—they assert a reset signal whenever the VCC supply voltage declines below a preset threshold, keeping it asserted for a preset timeout period after V CC has risen above the reset threshold. The only difference among the three devices is their output. The MAX6801 (push/pull) and MAX6802 (open-drain) have an active-low RESET output, while the MAX6800 (push/pull) has an active-high RESET output. The MAX6800/MAX6801 are guaranteed to be in the correct state for VCC down to 0.7V. The MAX6802 is guaranteed to be in the correct state for VCC down to 1.0V. The reset comparator in these ICs is designed to ignore fast transients on VCC. Reset thresholds are factorytrimmable between 2.63V and 4.80V, in approximately 100mV increments. These devices are available with a 1ms (min), 20ms (min), or 100ms (min) reset pulse width. Ideal for space-critical applications, the MAX6800/MAX6801/MAX6802 come packaged in a 3pin SOT23. For a lower threshold voltage version, see the MAX6332/MAX6333/MAX6334. Applications Features ♦ Ultra-Low 0.7V Operating Supply Voltage ♦ Low 4.0µA Supply Current ♦ Precision Monitoring of 2.85V to 5.0V PowerSupply Voltages ♦ Reset Thresholds Available from 2.63V to 4.80V, in Approximately 100mV Increments ♦ Fully Specified over Temperature ♦ Three Power-On Reset Timeout Periods Available (1ms min, 20ms min, 100ms min) ♦ Low Cost ♦ Three Available Output Structures: Push/Pull RESET, Push/Pull RESET, Open-Drain RESET ♦ Guaranteed RESET/RESET Valid to VCC = 0.7V (MAX6800/MAX6801) ♦ Power-Supply Transient Immunity ♦ No External Components Required ♦ 3-Pin SOT23 Package ♦ Pin Compatible with MAX809/MAX810, MAX6326/MAX6327/MAX6328, and MAX6346/MAX6347/MAX6348 Computers Controllers Ordering Information Intelligent Instruments Critical µP/µC Power Monitoring Portable/Battery-Powered Equipment Automotive TEMP RANGE PIN-PACKAGE MAX6800UR_ _D_-T -40°C to +125°C 3 SOT23-3 MAX6801UR_ _D_-T -40°C to +125°C -40°C to +125°C 3 SOT23-3 3 SOT23-3 PART* MAX6802UR_ _D_-T Typical Operating Circuit and Pin Configuration appear at end of data sheet. Selector Guide appears at end of data sheet. *These devices are available in factory-set VCC reset thresholds from 2.63V to 4.80V, in approximately 0.1V increments. Choose the desired reset threshold suffix from Table 1 and insert it in the blanks following “UR” in the part number. Factory-programmed reset timeout periods are also available. Insert the number corresponding to the desired nominal reset timeout period (1 = 1ms min, 2 = 20ms min, 3 = 100ms min) in the blank following “D” in the part number. There are 15 standard versions with a required order increment of 2500 pieces. Sample stock is generally held on the standard versions only (see Selector Guide). Contact the factory for availability of nonstandard versions (required order increment is 10,000 pieces). All devices 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. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX6800/MAX6801/MAX6802 General Description MAX6800/MAX6801/MAX6802 3-Pin, Low-Power µP Reset Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC ......................................................................-0.3V to +6V Push/Pull RESET, RESET .......................-0.3V to (VCC + 0.3V) Open-Drain RESET ..............................................-0.3V to +6V Input Current (VCC) .............................................................20mA Output Current (RESET, RESET).........................................20mA Continuous Power Dissipation (TA = +70°C) 3-Pin SOT23 (derate 4mW/°C above +70°C) ..............320mW 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 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 +125°C, unless otherwise noted. Typical values are at VCC = +5.0V and TA = +25°C, reset not asserted.) (Note 1) PARAMETER Supply Voltage Range (Note 2) SYMBOL CONDITIONS TA = 0°C to +125°C VCC TA = -40°C to +125°C Supply Current Reset Threshold ICC VTH No load MAX680_UR_ _D_-T, Table 1 Reset Active Timeout Period RESET Output Low Voltage (MAX6801/MAX6802) RESET Output High Voltage (MAX6801) RESET Output Voltage (MAX6800) VOL 0.7 5.5 1.0 5.5 MAX6800/MAX6801 0.78 5.5 MAX6802 1.2 4 10 VCC = +5.0V 5 12 VTH - 1.8% VTH VTH + 1.8% VTH - 3% VTH VTH + 3% TA = +25°C RESET Output Leakage Current (MAX6802) 30 1 1.5 2 30 40 MAX680_UR_ _D3-T 100 150 200 VOH Reset asserted Reset not asserted µA µs 20 Reset not asserted V V MAX680_UR_ _D2-T Reset asserted UNITS 5.5 VCC = +3.0V MAX680_UR_ _D1-T VOH VOL MAX MAX6802 VCC falling at 10V/ms tRP TYP MAX6800/MAX6801 TA = -40°C to +125°C VCC Falling Reset Delay MIN ISINK = 50µA, VCC ≥ 1.0V 0.4 ISINK = 1.2mA, VCC ≥ 2.5V 0.3 ISINK = 1.2mA, VCC ≥ 4.25V 0.4 ISOURCE = 500µA, VCC ≥ 3.0V 0.8 x VCC ISOURCE = 800µA, VCC ≥ 5.0V 0.8 x VCC ISOURCE = 1µA, VCC ≥ 1.0V 0.8 x VCC ISOURCE = 200µA, VCC ≥ 1.8V 0.8 x VCC ISOURCE = 800µA, VCC ≥ 4.25V 0.8 x VCC V V V ISINK = 1.2mA, VCC ≥ 3.0V 0.3 ISINK = 3.2mA, VCC ≥ 5.0V 0.4 VCC > VTH, RESET not asserted ms 0.5 µA Note 1: All parts are production tested at TA = +25°C. Overtemperature limits are guaranteed by design and not production tested. Note 2: ISOURCE for the MAX6800 is I00nA. ISINK for the MAX6801 is 100nA. ISINK for the MAX6802 is 50µA. 2 _______________________________________________________________________________________ 3-Pin, Low-Power µP Reset Circuits NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE 5.0 4.5 VCC = +3.3V 4.0 3.5 1.020 1.010 1.000 0.990 0.980 0.970 80 VTH = 2.93V ISINK = 500µA RESET ASSERTED MAX6801/MAX6802 +125°C 60 +85°C 40 +25°C -40°C 20 0.960 3.0 0.950 -25 0 25 50 75 100 125 0 -50 -25 0 25 50 75 100 125 1.5 2.0 2.5 3.0 TEMPERATURE (°C) VCC (V) RESET (VOH) vs. SUPPLY VOLTAGE MAXIMUM TRANSIENT DURATION vs. RESET COMPARATOR OVERDRIVE VCC FALLING PROPAGATION DELAY vs. TEMPERATURE +125°C 50 +85°C +25°C 25 500 400 RESET OCCURS 300 200 RESET DOES NOT OCCUR 100 2.0 2.5 VCC (V) 70 VCC = FALLING AT 1V/ms 60 50 40 30 VCC = FALLING AT 10V/ms 0 0.1 3.0 80 10 0 1.5 90 20 -40°C 0 100 MAX6800/01/02 toc06 75 600 PROPAGATION DELAY (µs) VTH = 2.93V ISOURCE = 100µA RESET ASSERTED (MAX6800) MAXIMUM TRANSIENT DURATION (µs) 100 1.0 1.0 TEMPERATURE (°C) MAX6800/01/02 toc04 -50 OUTPUT VOLTAGE HIGH (VCC - VOH) (mV) 1.030 MAX6800/01/02 toc05 ICC (µA) VCC = +5.0V 1.040 MAX6800/01/02 toc03 5.5 MAX6800/01/02 toc02 6.0 1.050 NORMALIZED RESET TIMEOUT PERIOD MAX6800/01/02 toc01 6.5 RESET (VOL) vs. SUPPLY VOLTAGE OUTPUT VOLTAGE LOW (mV) SUPPLY CURRENT vs. TEMPERATURE 1 10 100 1000 RESET COMPARATOR OVERDRIVE (mV) -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) Pin Description PIN MAX6800 1 MAX6801/ MAX6802 1 NAME GND FUNCTION Ground — 2 RESET Active-Low Reset Output. RESET is asserted while VCC is below the reset threshold and remains asserted for a reset timeout period (tRP) after VCC rises above the reset threshold. RESET on the MAX6801 is push/pull. RESET on the MAX6802 is open-drain. 2 — RESET Active-High Reset Output. RESET is asserted while VCC is below the reset threshold and remains asserted for a reset timeout period (tRP) after VCC rises above the reset threshold. RESET on the MAX6800 is push/pull. 3 3 VCC Supply Voltage Input _______________________________________________________________________________________ 3 MAX6800/MAX6801/MAX6802 Typical Operating Characteristics (Reset not asserted, TA = +25°C, unless otherwise noted.) MAX6800/MAX6801/MAX6802 3-Pin, Low-Power µP Reset Circuits Applications Information Interfacing to µPs with Bidirectional Reset Pins Since the RESET output on the MAX6802 is open-drain, this device interfaces easily with µPs that have bidirectional reset pins, such as the Motorola 68HC11. Connecting the µP supervisor’s RESET output directly to the microcontroller’s (µC’s) RESET pin with a single pullup resistor allows either device to assert reset (Figure 1). Negative-Going VCC Transients In addition to issuing a reset to the µP during power-up, power-down, and brownout conditions, these devices are relatively immune to short-duration, negative-going VCC transients (glitches). The Typical Operating Characteristics show the Maximum Transient Duration vs. Reset Comparator Overdrive graph. The graph shows the maximum pulse width that a negative-going VCC transient may typically have without issuing a reset signal. As the amplitude of the transient increases, the maximum allowable pulse width decreases. VCC VCC VCC VCC VCC 100kΩ MAX6802 RESET 100kΩ* µP MOTOROLA 68HCXX RESET GND MAX6801 MAX6800 RESET RESET 100kΩ GND GND (a) GND (b) *ASSUMES HIGH-Z RESET INPUT TO THE µP Figure 1. Interfacing to µPs with Bidirectional Reset Pins Figure 2. Ensuring Reset Valid Down to VCC = 0 Pin Configuration Typical Operating Circuit TOP VIEW VCC GND 1 MAX6800 MAX6801 MAX6802 3 VCC VCC VCC MAX6801 µP RESET RESET GND RESET (RESET) 2 SOT23-3 ( ) ARE FOR MAX6800 4 _______________________________________________________________________________________ GND 3-Pin, Low-Power µP Reset Circuits When VCC falls below 1V and approaches the minimum operating voltage of 0.7V, push/pull-structured reset sinking (or sourcing) capabilities decrease drastically. High-impedance CMOS-logic inputs connected to the RESET pin can drift to indeterminate voltages. This does not present a problem in most cases, since most µPs and circuitry do not operate when V CC drops below 1V. For the MAX6801 application, where RESET must be valid down to 0, adding a pulldown resistor between RESET and GND removes stray leakage currents, holding RESET low (Figure 2a). The pulldown resistor value is not critical; 100kΩ is large enough not to load RESET and small enough to pull it low. For the MAX6800 application, where RESET must be valid to VCC = 0, a 100kΩ pullup resistor between RESET and VCC will hold RESET high when VCC falls below 0.7V (Figure 2b). Since the MAX6802 has an open-drain, active-low output, it typically uses a pullup resistor. With this device, RESET will most likely not maintain an active condition, but will drift to a non-active level due to the pullup resistor and the reduced sinking capability of the opendrain device. Therefore, this device is not recommended for applications where the RESET pin is required to be valid down to VCC = 0. Table 1. Factory-Trimmed Reset Thresholds RESET THRESHOLD SUFFIX MIN TYP (VTH) MAX MIN MAX 48 4.714 4.80 4.886 4.656 4.944 47 4.615 4.70 4.785 4.559 4.841 46 4.547 4.63 4.713 4.491 4.769 45 4.419 4.50 4.581 4.365 4.635 44 4.301 4.38 4.459 4.249 4.511 43 4.223 4.30 4.377 4.171 4.429 42 4.124 4.20 4.276 4.074 4.326 41 4.026 4.10 4.174 3.977 4.223 40 3.928 4.00 4.072 3.880 4.120 39 4.830 3.90 3.970 3.783 4.017 38 3.732 3.80 3.868 3.686 3.914 37 3.633 3.70 3.767 3.589 3.811 36 3.535 3.60 3.665 3.492 3.708 35 3.437 3.50 3.563 3.395 3.605 34 3.339 3.40 3.461 3.298 3.502 33 3.241 3.30 3.359 3.201 3.399 32 3.142 3.20 3.258 3.104 3.296 31 3.025 3.08 3.135 2.988 3.172 30 2.946 3.00 3.054 2.910 3.090 29 2.877 2.93 2.983 2.842 3.018 28 2.750 2.80 2.850 2.716 2.884 27 2.651 2.70 2.749 2.619 2.781 26 2.583 2.63 2.677 2.551 2.709 TA = +25°C TA = -40°C to +125°C _______________________________________________________________________________________ 5 MAX6800/MAX6801/MAX6802 Ensuring a Valid Reset Output Down to VCC = 0 MAX6800/MAX6801/MAX6802 3-Pin, Low-Power µP Reset Circuits Selector Guide (Standard Versions*) PART OUTPUT STAGE NOMINAL VTH (V) MIN RESET TIMEOUT (ms) SOT TOP MARK MAX6800UR26D3-T Push/Pull RESET 2.63 100 FZIE MAX6800UR29D3-T Push/Pull RESET 2.93 100 FZIF MAX6800UR31D3-T Push/Pull RESET 3.08 100 FZIG MAX6800UR44D3-T Push/Pull RESET 4.38 100 FZIH MAX6800UR46D3-T Push/Pull RESET 4.63 100 FZII MAX6801UR26D3-T Push/Pull RESET 2.63 100 FZIK MAX6801UR29D3-T Push/Pull RESET 2.93 100 FZIM MAX6801UR31D3-T Push/Pull RESET 3.08 100 FZIN MAX6801UR44D3-T Push/Pull RESET 4.38 100 FZIO MAX6801UR46D3-T Push/Pull RESET 4.63 100 FZIP MAX6802UR26D3-T Open-Drain RESET 2.63 100 FZIQ MAX6802UR29D3-T Open-Drain RESET 2.93 100 FZIR MAX6802UR31D3-T Open-Drain RESET 3.08 100 FZIS MAX6802UR44D3-T Open-Drain RESET 4.38 100 FZIT MAX6802UR46D3-T Open-Drain RESET 4.63 100 FZIU *Sample stock is generally held on all standard versions. Chip Information TRANSISTOR COUNT: 505 PROCESS: BiCMOS 6 _______________________________________________________________________________________ 3-Pin, Low-Power µP Reset Circuits SOT23 L.EPS PACKAGE OUTLINE, 3L SOT-23 21-0051 F 1 1 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. 7 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX6800/MAX6801/MAX6802 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)