19-1421; Rev 1; 4/99 Voltage Detectors The MAX6806/MAX6807/MAX6808 precision voltage detectors are ideal for accurate monitoring of power supplies in digital systems. They provide circuit reliability and reduce total cost by eliminating external components and adjustments. The MAX6806/MAX6807/MAX6808 assert a reset signal whenever the supply voltage (VCC) falls below the factorypreset, ±2% accurate threshold. Internal hysteresis ensures stable switching. The MAX6806/MAX6807/ MAX6808 are available in 4.6V and 2.6V thresholds (2.3V is also available for the MAX6806 only). The MAX6806 features an active-low, push-pull RESET output; the MAX6807 features an active-high, push-pull RESET output; and the MAX6808 features an active-low, open-drain RESET output. RESET is valid for V CC down to 1V (MAX6806/ MAX6808), and RESET (MAX6807) is guaranteed for VCC down to 1.2V. The MAX6806/MAX6807/MAX6808 are available in 3-pin SC70, 3-pin SOT23, and 4-pin SOT143 packages. The SOT143 package includes a manual-reset input. Features ♦ Preset Reset Thresholds: 4.6V and 2.6V (2.3V also available for MAX6806 only) ♦ ±2% Accurate Reset Thresholds ♦ Reset Output Available in Active-Low (MAX6806), Active-High (MAX6807), and Open-Drain (MAX6808) Versions ♦ Immune to Power-Supply Transients ♦ RESET Valid to VCC = 1.0V (MAX6806/MAX6808) ♦ 35µA Supply Current ♦ No External Components ♦ Manual Reset Available with 4-Pin SOT143 Package ♦ Miniature 3-Pin SC70, 3-Pin SOT23, and 4-Pin SOT143 Packages Ordering Information Applications PART TEMP. RANGE PIN-PACKAGE Computers Controllers MAX6806XR_ _-T -40°C to +85°C 3 SC70 MAX6806UR_ _-T -40°C to +85°C 3 SOT23 Intelligent Instruments Critical µP and µC Power Monitoring MAX6806US_ _-T -40°C to +85°C 4 SOT143 MAX6807XR_ _-T -40°C to +85°C 3 SC70 Portable/Battery-Powered Equipment Automotive MAX6807UR_ _-T -40°C to +85°C 3 SOT23 MAX6807US_ _-T -40°C to +85°C 4 SOT143 Bar-Code Scanners MAX6808XR_ _-T -40°C to +85°C 3 SC70 MAX6808UR_ _-T -40°C to +85°C 3 SOT23 MAX6808US_ _-T -40°C to +85°C 4 SOT143 Typical Operating Circuit and Pin Configurations appear at end of data sheet. * All devices available in tape-and-reel only, 2500 piece minimum order quantity. Note: Insert the desired number from the Selector Guide into the blank to complete the part number. Also see Selector Guide for top mark. Selector Guide PART RESET OUTPUT MAX6806UR46-T MAX6806UR26-T MAX6806UR23-T Active-Low, Push-Pull MAX6806US46-T MAX6806US26-T MAX6806US23-T † Other reset thresholds may be available. Contact factory for availability. TOP MARK NOMINAL VTH- (V)† FZDP FZDQ FZDR KABT KABU KABV 4.6 2.6 2.3 4.6 2.6 2.3 Selector Guide continued at end of data sheet. ________________________________________________________________ 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. MAX6806/MAX6807/MAX6808 General Description MAX6806/MAX6807/MAX6808 Voltage Detectors ABSOLUTE MAXIMUM RATINGS VCC to GND ..........................................................-0.3V to +6.0V RESET, RESET to GND (MAX6806/MAX6807) ................................-0.3V to (VCC + 0.3V) RESET to GND (MAX6808)...................................-0.3V to + 6.0V MR to GND (SOT143 package only) ....................-0.3V to + 6.0V Input Current, VCC ...........................................................±20mA Output Current, RESET, RESET .......................................±20mA Rate of Rise, VCC ...........................................................100V/µs Continuous Power Dissipation (TA = +70°C) SOT23, SOT143 (derate 4mW/°C above +70°C) .........320mW SC70 (derate 2.17mW/°C above +70°C) .....................174mW Operating Temperature Range ..........................-40°C to +85°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 = +5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Supply Voltage Range VCC Supply Current ICC Reset Threshold Reset Threshold Hysteresis RESET Output Voltage (MAX6806/MAX6808) VTH- VHYST VOL CONDITIONS TA = -40°C to +85°C 1.2 5.5 VCC = +3.6V, no load 35 60 VCC = +5.5V, no load 50 80 TA = +25°C, VCC falling MAX680_ _ _46 4.508 4.60 4.692 MAX680_ _ _26 2.548 2.60 2.652 MAX680_ _ _23 2.254 2.30 2.346 0.02 VTH- 0.03 VTH- TA = +25°C, Figure 2 ISINK = 20µA, VCC = 1.0V 0.3 ISINK = 1.0mA, VCC = 2.0V 0.4 RESET Output Leakage Current IOH VCC = 5.5V, RESET deasserted (MAX6808 only) RESET Output Voltage (MAX6807) VOH MR Input Threshold 0.8VCC ISOURCE = 400µA, VCC = 2.0V 0.8VCC VIL V V V 0.4 40 VCC > VTH+ µA V ISINK = 3.2mA, VCC = 5.0V VCC falling at 1mV/µs VIH V µA ISOURCE = 20µA, VCC = 1.2V RMR UNITS 0.8VCC Reset Threshold Tempco MR Pull-Down Resistance MAX 5.5 ISOURCE = 2.0mA, VCC = 5.0V (MAX6806 only) VCC to Reset Delay (Note 2) TYP 1.0 VOH VOL MIN TA = 0°C to +70°C 30 µs 30 ppm/°C 80 120 0.6 0.7VCC kΩ V Note1: All devices are 100% production tested at TA = +25°C, and are guaranteed by design for TA = TMIN to TMAX, as specified. Note 2: RESET output for MAX6806/MAX6808, RESET output for MAX6807. 2 _______________________________________________________________________________________ Voltage Detectors POWER-DOWN RESET DELAY vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE VCC = 5.0V 41 RESET DELAY (µs) 35 VCC = 3.3V 30 25 VCC = 1.8V 20 VOD = VTH- - VCC = 100mV VCC FALLING AT 1mV/µS 43 39 37 35 33 31 15 10 29 VCC = 1.0V 27 5 25 0 -60 -30 0 30 60 90 -60 -45 -30-15 0 15 30 45 60 75 90 105 120135 120 TEMPERATURE (°C) TEMPERATURE (°C) NORMALIZED RESET THRESHOLD vs. TEMPERATURE POWER-UP RESET DELAY vs. TEMPERATURE 11 1.0100 1.0080 NORMALIZED RESET THRESHOLD VOD = VCC - VTH+ MAX6806/7/8-03 12 DELAY TIME (µs) 10 9 VOD = 50mV 8 7 VOD = 100mV 6 5 VOD = 200mV MAX6806/7/8-04 SUPPLY CURRENT (µA) 40 45 MAX6806/7/8toc02 45 MAX6806/7/8-01 50 VCC RISING (VTH+) 1.0060 1.0040 1.0020 1.0000 0.9980 0.9960 VCC FALLING (VTH-) 0.9940 0.9920 0.9900 4 -60 -30 0 30 60 90 -40 -30 -15 120 0 15 30 45 60 75 85 TEMPERATURE (°C) TEMPERATURE (°C) Pin Description PIN SOT23/SC70 1 NAME FUNCTION RESET Active-Low Reset Output (MAX6806/MAX6808). RESET remains low while VCC is below the reset-threshold voltage or while MR is held high. RESET Active-High Reset Output (MAX6807). RESET remains high while VCC is below the reset-threshold voltage or while MR is held high. SOT143 1 2 4 GND Ground 3 3 VCC Supply Voltage Input — 2 MR Active-High Manual Reset Input. Internal 80kΩ resistor to GND. _______________________________________________________________________________________ 3 MAX6806/MAX6807/MAX6808 Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) MAX6806/MAX6807/MAX6808 Voltage Detectors _______________Detailed Description Reset Output The MAX6806 voltage detector features an active-low, push-pull RESET output, while the MAX6807 features an active-high, push-pull RESET output. Unlike microprocessor (µP) supervisory circuits that offer a reset timeout period, the MAX6806 and MAX6807 RESET goes high and RESET goes low virtually immediately once VCC exceeds the reset threshold. If a brownout occurs (VCC falls below the reset threshold), RESET goes low and RESET goes high. RESET is guaranteed to be a logic low for VCC ≥ 1V and RESET is guaranteed to be a logic high for VCC ≥ 1.2V. The MAX6808 features an active-low, open-drain RESET output. The output sinks current when VCC falls below the reset threshold. Connect a pull-up resistor from RESET to any supply voltage up to 6V (Figure 1). Select a resistor value large enough to provide a logic low and small enough to provide a logic high while supplying all input and leakage currents connected to the RESET line. A 100kΩ resistor is sufficient in applications driving high-impedance loads. The manual reset input (MR, 4-pin SOT143 package) can also initiate a reset (see Manual Reset Input section). +3.3V Manual Reset Input Many applications require manual-reset capabilities, allowing an operator, a test technician, or external logic circuitry to initiate a reset. A logic high on MR asserts a reset and remains asserted while MR is high. This input has an 80kΩ pull-down resistor, so the input may be left unconnected if not used. Connect a normally open momentary switch from MR to VCC to create a manualreset function. If MR is driven from long cables or if the device is used in a noisy environment, connecting a 0.1µF capacitor from MR to ground provides noise immunity. Hysteresis The MAX6806/MAX6807/MAX6808 feature internal hysteresis that creates two trip points: one for the rising supply voltage and one for the falling supply voltage (Figure 2). The hysteresis prevents the output from oscillating (chattering) when VCC is near the reset threshold. Reset Threshold Accuracy The MAX6806/MAX6807/MAX6808 are ideal for systems using a 5V ±5%, 3V ±5%, or 2.5V ±5% power supply with ICs specified for 5V ±10%, 3V ±10%, or 2.5V ±10%, respectively. The reset is guaranteed to assert after the power supply falls out of regulation, but before power drops below the minimum specified operating voltage range for the system ICs. +5.0V VTH+ HYST VCC VCC 100k MAX6808 VHYST = VTH+ - VTH- VTH- VOH 5V SYSTEM RESET (MAX6806/MAX6808) VOL RESET VOH GND GND RESET (MAX6807) Figure 1. The MAX6808 open-drain RESET output allows use with multiple supplies. 4 VOL Figure 2. Input and Output Waveforms with VCC Varied _______________________________________________________________________________________ Voltage Detectors Negative-Going VCC Transients In addition to asserting a reset signal during power-up, power-down, and brown-out conditions, the MAX6806/ MAX6807/MAX6808 are immune to short-duration, negative-going VCC transients. Figure 3 displays typical transient durations vs. resetcomparator overdrive for which the MAX6806/MAX6807/ MAX6808 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 further below the reset threshold), the maximum allowable pulse width decreases. A 0.1µF capacitor mounted as close as possible to VCC provides additional transient immunity. Ensuring a Valid Reset Output Down to VCC = Ground When V CC falls below 1V, the MAX6806/MAX6808 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 circuitry is inoperative when VCC is below 1V. In applications where RESET must be valid down to ground, add a pull-down resistor to RESET so any stray leakage currents flow to ground, holding RESET low (Figure 4). Select R1 to be large enough not to load RESET and small enough to pull RESET to ground. For most applications, 100kΩ will not load RESET and will pull RESET to ground. Similarly, if RESET (MAX6807) must be valid below 1.2V, add a pull-up resistor to RESET. 80 MAXIMUM TRANSIENT DURATION (µs) TA = +25°C 70 VCC VCC 60 R1 100k 50 MAX6806 MAX6807 40 MAX680 46 RESET RESET 30 R1 100k 20 10 100 1000 GND GND RESET COMPARATOR OVERDRIVE, VTH- - VCC (mV) Figure 3. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive Figure 4. RESET / RESET Valid to VCC = Ground Circuit _______________________________________________________________________________________ 5 MAX6806/MAX6807/MAX6808 Applications Information MAX6806/MAX6807/MAX6808 Voltage Detectors Interfacing to µPs with Bidirectional Reset Pins µPs with bidirectional reset pins (such as the Motorola 68HC11 series) can contend with push-pull RESET outputs, resulting in indeterminate logic levels. Use the MAX6808 with the open-drain RESET when interfacing to this type of controller. VCC VCC VCC 4.7k µP MAX6808 RESET RESET GND GND Figure 5. Interfacing to µPs with Bidirectional Reset I/O Selector Guide (continued) TOP MARK NOMINAL VTH- (V)† AAA AAB AAC FZDS FZDT KABW KABX AAD AAE FZDU FZDV KABY KABZ 4.6 2.6 2.3 4.6 2.6 4.6 2.6 4.6 2.6 4.6 2.6 4.6 2.6 MAX6808XR46-T AAF 4.6 MAX6808XR26-T AAG 2.6 PART* MAX6806XR46-T MAX6806XR26-T MAX6806XR23-T MAX6807UR46-T MAX6807UR26-T MAX6807US46-T MAX6807US26-T MAX6807XR46-T MAX6807XR26-T MAX6808UR46-T MAX6808UR26-T MAX6808US46-T MAX6808US26-T RESET OUTPUT Active-Low, Push-Pull Active-High, Push-Pull Active-Low, Open-Drain † Other reset thresholds may be available. Contact factory for availability. 6 _______________________________________________________________________________________ Voltage Detectors TOP VIEW (RESET)/RESET (RESET)/RESET 1 4 GND 3 VCC 1 MAX6806 MAX6807 MAX6808 GND 2 3 MAX6806 MAX6807 MAX6808 VCC MR 2 SOT23/SC70 SOT143 ( ) ARE FOR MAX6807 Typical Operating Circuit VCC VCC VCC MAX6806 MAX6807 MAX6808 (RESET)/RESET GND µP RESET INPUT GND ( ) ARE FOR MAX6807 ___________________Chip Information TRANSISTOR COUNT: 72 _______________________________________________________________________________________ 7 MAX6806/MAX6807/MAX6808 Pin Configurations Voltage Detectors SC70, 3L.EPS MAX6806/MAX6807/MAX6808 Package Information 8 _______________________________________________________________________________________ Voltage Detectors SOTPO3L.EPS _______________________________________________________________________________________ 9 MAX6806/MAX6807/MAX6808 Package Information (continued) Voltage Detectors SOT1434.EPS MAX6806/MAX6807/MAX6808 Package Information (continued) 10 ______________________________________________________________________________________ Voltage Detectors ______________________________________________________________________________________ MAX6806/MAX6807/MAX6808 NOTES 11 MAX6806/MAX6807/MAX6808 Voltage Detectors NOTES 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. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.