19-2523; Rev 0; 7/02 Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset Features The MAX6467/MAX6468 microprocessor (µP) supervisory circuits monitor single power-supply voltages from +1.8V to +5.0V and assert a reset if the supply voltage drops below its preset threshold. An edge-triggered, one-shot manual reset function ensures that the µP enters the reset mode for a fixed timeout period only, even in the event of a continuously asserted manual reset. The MAX6467/MAX6468 significantly improve system reliability compared to traditional manual reset supervisory circuits. A variety of factory-trimmed threshold options accommodate different supply voltages and tolerances, eliminating external components. The factory-set thresholds range from +1.575V to +4.625V to monitor +5.0V, +3.3V, +3.0V, +2.5V, and +1.8V supplies with various tolerances. Reset timeout periods of 150ms (min) and 1200ms (min) are available to accommodate different µP platforms. ♦ Precision Factory-Set Reset Threshold Voltages for +5.0V, +3.3V, +3.0V, +2.5V, and +1.8V Supplies A single, active-low RESET output asserts when VCC drops below its threshold or if the edge-triggered MR asserts low. RESET remains low for the reset timeout period after VCC rises above its threshold and for a fixed, one-shot timeout period after a manual reset input falling edge. RESET remains valid as long as VCC remains above +1V. Open-drain (MAX6467) and push-pull (MAX6468) output options provide additional flexibility in the system design. The MAX6467/MAX6468 are offered in the space-saving 4-pin SOT143 package and the ultra-small 4-pin SC70 package and are specified over the automotive (-40°C to +125°C) temperature range. Applications Cell Phones/PDAs Embedded Control Systems Industrial Equipment ♦ Edge-Triggered Manual Reset Input with OneShot Pulsed Reset Output ♦ Two Reset Timeout Period Options (150ms or 1200ms min) ♦ Immune to Short Voltage Transients ♦ Low Supply Current (3µA at VCC = +1.8V) ♦ RESET Valid to VCC = +1V ♦ Active-Low Open-Drain and Push-Pull RESET Output Options ♦ -40°C to +125°C Operating Temperature Range ♦ Small 4-Pin SC70 and SOT143 Packages ♦ No External Components Required ♦ Pin Compatible with MAX811, MAX6315, MAX6384, and MAX6386 Ordering Information PART MAX6467XS_ _D_-T MAX6467US_ _D_-T MAX6468XS_ _D_-T MAX6468US_ _D_-T PIN-PACKAGE 4 SC70-4 4 SOT143-4 4 SC70-4 4 SOT143-4 Note: Insert reset threshold suffix (see Reset Threshold table) after XS or US. Insert reset timeout delay (see Reset Timeout Delay table) after D to complete the part number. Sample stock is generally held on standard versions only (see Standard Versions table). Standard versions have an order increment requirement of 2500 pieces. Nonstandard versions have an order increment requirement of 10,000 pieces. Contact factory for availability. Automotive Products Pin Configurations Portable/Battery-Powered Equipment Medical Devices TEMP RANGE -40°C to +125°C -40°C to +125°C -40°C to +125°C -40°C to +125°C TOP VIEW DSL Modems MP3 Players GND 1 GPS Systems Digital Cameras RESET 2 MAX6467XS MAX6468XS 4 VCC 3 MR SC70 Typical Operating Circuit appears at end of data sheet. Pin Configurations continued at end of data sheet. ________________________________________________________________ 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 MAX6467/MAX6468 General Description MAX6467/MAX6468 Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset 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 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 VCC to GND ...........................................................-0.3V to +6.0V RESET to GND Open-Drain........................................................-0.3V to +6.0V Push-Pull.................................................-0.3V to (VCC + 0.3V) MR to GND .................................................-0.3V to (VCC + 0.3V) Input/Output Current (all pins) ............................................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 = +1.2V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Operating Voltage Range Supply Current SYMBOL VCC ICC CONDITIONS MIN VTH 1.0 5.5 TA = -40°C to 0°C 1.2 5.5 VCC = +5.5V, no load 7 13 VCC = +3.6V, no load 6 11 VCC = +2.5V, no load 4 8 tRD VCC Reset Timeout Period tRP 3 7.5 VTH +1.5% TA = +25°C -1.5% TA = -40°C to +85°C -2.5% +2.5% -3% +3% TA = +85°C to +125°C VCC Reset Delay MAX TA = 0°C to +125°C VCC = +1.8V, no load VCC Reset Threshold (See the Reset Threshold Table) TYP VCC falling at 10mV/µs from VTH + 100mV to VTH - 100mV 35 UNITS V µA V µs D3 option 150 225 300 D7 option 1200 1800 2400 ms MR Timeout Period tMRP D3 and D7 options 150 225 300 ms MR Rising Debounce Period (Note 2) tDEB D3 and D7 options 150 225 300 ms VIL MR Input Voltage VIH VIL VIH VTH < +4V VTH ≥ +4V MR Minimum Input Pulse 0.3 x VCC 0.7 x VCC 0.8 2.4 1 MR Glitch Rejection MR to RESET Delay RESET Output High (MAX6468 Only) 2 µs 100 ns 200 MR Pullup Resistance MR to VCC VCC ≥ +2.5V, ISOURCE = 500µA, RESET not asserted VOH VCC ≥ +4.5V, ISOURCE = 800µA, RESET not asserted V 750 1500 ns 2250 Ω 0.8 x VCC V 0.8 x VCC _______________________________________________________________________________________ Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset (VCC = +1.2V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL RESET Output Low VOL RESET Output Leakage Current (MAX6467 Only) CONDITIONS MIN TYP MAX VCC ≥ +1V, ISINK = 80µA, RESET asserted 0.3 VCC ≥ +2.5V, ISINK = 1.2mA, RESET asserted 0.3 VCC ≥ +4.5V, ISINK = 3.2mA, RESET asserted 0.3 RESET not asserted ILKG UNITS V 1 µA Note 1: Specifications over temperature are guaranteed by design. Production testing at TA = +25°C only. Note 2: The MR input ignores falling edges that occur within the MR rising debounce period (tDEB) after MR first rises from low to high (after a valid MR reset assertion). This prevents invalid reset assertion due to switch bounce. Typical Operating Characteristics (VCC = +5V, MAX6468US29D3 device, TA = +25°C, unless otherwise noted.) 6 5 4 3 VCC = +2.5V 6 5 4 3 2 VCC = +1.8V 1 MAX6467 toc03 VCC = VTH + 100mV TO VTH - 100mV 24 22 20 18 1 0 0 16 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) SUPPLY VOLTAGE (V) TEMPERATURE (°C) RESET TIMEOUT PERIOD vs. TEMPERATURE NORMALIZED RESET THRESHOLD vs. TEMPERATURE OUTPUT VOLTAGE LOW vs. SINK CURRENT 208 207 206 205 204 203 202 1.010 NORMALIZED RESET THRESHOLD (V) MAX6467 toc04 209 1.000 0.995 VCC = 5.0V 500 450 1.005 400 350 300 250 200 150 100 50 0 201 200 600 550 MAX6467 toc06 -40 -25 -10 5 20 35 50 65 80 95 110 125 210 RESET TIMEOUT PERIOD (ms) 7 VOL (mV) 2 8 VCC TO RESET DELAY (µs) 7 26 MAX6467 toc02 VCC = +3.6V 9 MAX6467 toc05 SUPPLY CURRENT (µA) 8 VCC = +5.5V 10 SUPPLY CURRENT (µA) 9 MAX6467 toc01 10 VCC TO RESET DELAY vs. TEMPERATURE SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE 0.990 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) 0 1 2 3 4 5 6 7 8 9 10 ISINK (mA) _______________________________________________________________________________________ 3 MAX6467/MAX6468 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VCC = +5V, MAX6468US29D3 device, TA = +25°C, unless otherwise noted.) 4.5 4.0 VOH (V) 3.5 3.0 2.5 2.0 1.5 1.0 600 MAX6467 toc08 VCC = +5.0V 5.0 MAXIMUM TRANSIENT DURATION (µs) 5.5 MAXIMUM TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE MAX6467 toc07 OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT 500 400 300 200 RESET ASSERTS ABOVE THIS LINE 100 0.5 0 0 0 1 2 3 4 5 6 7 8 0 10 20 30 40 50 ISOURCE (mA) RESET THRESHOLD OVERDRIVE (mV) MR TO RESET DELAY vs. TEMPERATURE PROPAGATION DELAY (WITH 100mV OVERDRIVE) 60 MAX6467 toc10 MAX6467 toc09 120 115 110 MR TO RESET DELAY (ns) MAX6467/MAX6468 Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset 3.0V VCC 100mV/div AC-COUPLED 105 100 95 2.8V 3V 90 85 80 75 70 65 60 RESET 1V/div 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 4µs/div TEMPERATURE (°C) RESET PULLUP AND PULLDOWN RESPONSE RESET TIMEOUT PERIOD MAX6467 toc12 MAX6467 toc11 CRESET = 47pF, RPULLUP = 100kΩ, VPULLUP = 1.6V 3.3V VCC 2V/div 1.675V VCC 200mV/div 1.475V 0 1.6V 3.3V RESET 500mV/div RESET 2V/div 0 0 MAX6467_S16D3-T 40µs/div 4 40ms/div _______________________________________________________________________________________ Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset PIN NAME 1 GND FUNCTION Ground Reset Output. RESET is an active-low open-drain (MAX6467) or push-pull (MAX6468) output. RESET asserts low when VCC drops below the selected threshold and remains low for the VCC reset timeout period after VCC rises above the threshold. The RESET one-shot asserts low for a fixed MR reset timeout period on the falling edge of the manual reset input. The open-drain output requires an external pullup resistor. 2 RESET 3 MR Manual Reset Input. Drive MR low to initiate a reset output. MR controls an edge-triggered one-shot that asserts RESET low for a fixed MR timeout period when MR is driven low. Internal timing circuitry ignores switch close and open bounce to ensure proper one-shot reset timing. 4 VCC Power-Supply Input. VCC provides power to the device and is also a monitored voltage. When VCC drops below the selected threshold, RESET asserts low and remains low for the reset timeout period after VCC rises above the threshold. For better noise immunity, bypass VCC to GND with a 0.1µF capacitor. VCC VTH GND SWITCH BOUNCE MR SWITCH BOUNCE SWITCH BOUNCE GND RESET tRP tMRP tDEB tMRP GND Figure 1. Timing Diagram Detailed Description Reset Output The MAX6467 provides an active-low open-drain RESET output. The MAX6468 provides an active-low push-pull RESET output. RESET asserts low if V CC drops below the selected threshold or if a falling edge occurs on MR. RESET remains low for the VCC reset timeout period after VCC increases above the threshold voltage or is one-shot pulsed low for the MR timeout period after a falling edge on MR. Manual Reset Input Many µP-based products require manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. A falling edge on MR asserts RESET low. RESET is one-shot pulsed low for the MR timeout period after a falling edge on MR. An internal 1.5kΩ pullup resistor to VCC allows MR to be left unconnected if not used. MR can be driven with TTL or CMOSlogic levels, or with open-drain/collector outputs. Connect a normally open momentary pushbutton switch from MR to GND to realize a manual reset function. External debounce circuitry is not required, as the MAX6467/ MAX6468 respond to the first falling edge on MR and ignore subsequent falling edges within the reset timeout period and during the MR debounce period (see Figure 1). After MR goes high for 150ms (tDEB), the manual reset one-shot is ready to trigger a reset on the next MR falling edge. Connect a 0.1µF capacitor from MR to GND when using long cables to provide additional noise immunity (Figure 2). _______________________________________________________________________________________ 5 MAX6467/MAX6468 Pin Description MAX6467/MAX6468 Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset Reset Timeout Delay* RESET TIMEOUT SUFFIX VCC RESET TIMEOUT PERIOD (min/max) (ms) MR TIMEOUT PERIOD (min/max) (ms) MR RISING DEBOUNCE PERIOD (min/max) (ms) D3 150/300 150/300 150/300 D7 1200/2400 150/300 150/300 *Additional reset timeout options may be available. Contact factory for availability. Applications Information Falling VCC Transients In addition to issuing a reset to the µP during power-up, power-down, and brownout conditions, the MAX6467/ MAX6468 are relatively immune to short-duration falling V CC transients (glitches). The Typical Operating Characteristics section shows the Maximum Transient Duration vs. V CC Overdrive for which the MAX6467/ MAX6468 do not generate a reset pulse. This graph was generated using a falling pulse applied to VCC starting above the actual reset threshold and ending below the threshold by the magnitude indicated (VCC Overdrive). The graph indicates the typical maximum pulse width a falling VCC transient can have without initiating a reset pulse. As the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width decreases. A 0.1µF bypass capacitor from VCC to GND provides additional transient immunity. Ensuring a Valid RESET Output Down to VCC = 0V The MAX6467/MAX6468 guarantee proper operation down to VCC = +1V. In applications that require valid reset levels down to VCC = 0V, a pulldown resistor to active-low outputs (MAX6468 only, Figure 3) ensures that RESET remains valid while the RESET output can no longer sink current. This scheme does not work with the open-drain outputs of the MAX6467. Ensure that the resistor value used does not overload the RESET output when VCC is above the reset threshold. For most applications, use 100kΩ to 1MΩ. VCC VCC MAX6467 MAX6468 1.5kΩ MR VCC MR ONE-SHOT/ DEBOUNCE RESET TIMEOUT PERIOD RESET MAX6468 R1 100kΩ RESET OUTPUT RESET GND VCC 1.23V Figure 3. RESET Valid to VCC = 0V GND Chip Information Figure 2. Functional Diagram 6 TRANSISTOR COUNT: 748 PROCESS: BiCMOS _______________________________________________________________________________________ Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset PART TOP MARK MAX6467XS16D3 AGL MAX6467XS22D3 MAX6467XS26D3 MAX6467XS29D3 Reset Threshold (-40°C to +85°C) SUFFIX VTH (min) VTH (typ) VTH (max) AGM 46 4.509 4.625 4.741 AGN 45 4.388 4.500 4.613 AGO 44 4.266 4.375 4.484 MAX6467XS46D3 AGP 43 4.193 4.300 4.408 MAX6467US16D3 KAFN 42 4.095 4.200 4.305 MAX6467US22D3 KAFO 41 3.998 4.100 4.203 MAX6467US26D3 KAFP 40 3.900 4.000 4.100 MAX6467US29D3 KAFQ 39 3.803 3.900 3.998 MAX6467US46D3 KAFR 38 3.705 3.800 3.895 MAX6468XS16D3 AGQ 37 3.608 3.700 3.793 MAX6468XS22D3 AGR 36 3.510 3.600 3.690 MAX6468XS26D3 AGS 35 3.413 3.500 3.588 MAX6468XS29D3 AGC 34 3.315 3.400 3.485 MAX6468XS46D3 AGB 33 3.218 3.300 3.383 MAX6468US16D3 KAFS 32 3.120 3.200 3.280 MAX6468US22D3 KAFT 31 2.998 3.075 3.152 MAX6468US26D3 KAFU 30 2.925 3.000 3.075 MAX6468US29D3 KAEW 29 2.852 2.925 2.998 MAX6468US46D3 KAFV 28 2.730 2.800 2.870 27 2.633 2.700 2.768 26 2.559 2.625 2.691 25 2.438 2.500 2.563 24 2.340 2.400 2.460 23 2.255 2.313 2.370 22 2.133 2.188 2.242 21 2.048 2.100 2.153 20 1.950 2.000 2.050 19 1.853 1.900 1.948 18 1.755 1.800 1.845 17 1.623 1.665 1.707 16 1.536 1.575 1.614 Typical Operating Circuit +1.0V TO +5.5V VCC VCC MAX6467 MAX6468 MR RESET RESET INPUT µP Pin Configurations (continued) GND GND TOP VIEW GND 1 RESET 2 MAX6467US MAX6468US 4 VCC 3 MR SOT143 _______________________________________________________________________________________ 7 MAX6467/MAX6468 Standard Versions MAX6467/MAX6468 Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset 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.) 8 _______________________________________________________________________________________ Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset SC70, 4L.EPS 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX6467/MAX6468 Package Information (continued) (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.)