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19-1933 Rev 1; 2/01
3-Pin, Low-Power P Reset Circuits
General Description
The MAX6800/MAX6801/MAX6802 microprocessor (P) supervisory circuits monitor the power supplies in 2.85V to 5.0V P 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. o Low 4.0A Supply Current o Precision Monitoring of 2.85V to 5.0V PowerSupply Voltages o Reset Thresholds Available from 2.63V to 4.80V, in Approximately 100mV Increments o Fully Specified over Temperature o Three Power-On Reset Timeout Periods Available (1ms min, 20ms min, 100ms min) o Low Cost o Three Available Output Structures: Push/Pull RESET, Push/Pull RESET, Open-Drain RESET o Guaranteed RESET/RESET Valid to VCC = 0.7V (MAX6800/MAX6801) o Power-Supply Transient Immunity o No External Components Required o 3-Pin SOT23 Package o Pin Compatible with MAX809/MAX810, MAX6326/MAX6327/MAX6328, and MAX6346/MAX6347/MAX6348
Features
o Ultra-Low 0.7V Operating Supply Voltage
MAX6800/MAX6801/MAX6802
Applications
Computers Controllers Intelligent Instruments Critical P/C Power Monitoring Portable/Battery-Powered Equipment Automotive
Ordering Information
PART*
MAX6800UR_ _D_-T MAX6801UR_ _D_-T MAX6802UR_ _D_-T
TEMP. RANGE -40C to +125C -40C to +125C -40C to +125C
PIN-PACKAGE 3 SOT23-3 3 SOT23-3 3 SOT23-3
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.
________________________________________________________________ Maxim Integrated Products
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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.
3-Pin, Low-Power P Reset Circuits MAX6800/MAX6801/MAX6802
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 = +70C) 3-Pin SOT23 (derate 4mW/C above +70C) ..............320mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = -40C to +125C, unless otherwise noted. Typical values are at VCC = +5.0V and TA = +25C, reset not asserted.) (Note 1)
PARAMETER Supply Voltage Range (Note 2) SYMBOL CONDITIONS TA = 0C to +125C VCC TA = -40C to +125C Supply Current ICC No load MAX6800/MAX6801 MAX6802 MAX6800/MAX6801 MAX6802 VCC = +3.0V VCC = +5.0V TA = +25C TA = -40C to +125C VCC Falling Reset Delay Reset Active Timeout Period tRP VCC falling at 10V/ms MAX680_UR_ _D1-T MAX680_UR_ _D2-T MAX680_UR_ _D3-T RESET Output Low Voltage (MAX6801/MAX6802) RESET Output High Voltage (MAX6801) VOL Reset asserted Reset not asserted Reset asserted Reset not asserted ISINK = 50A, VCC 1.0V ISINK = 1.2mA, VCC 2.5V ISINK = 1.2mA, VCC 4.25V ISOURCE = 500A, VCC 3.0V ISOURCE = 800A, VCC 5.0V ISOURCE = 1A, VCC 1.0V ISOURCE = 200A, VCC 1.8V ISOURCE = 800A, VCC 4.25V ISINK = 1.2mA, VCC 3.0V ISINK = 3.2mA, VCC 5.0V 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.3 0.4 0.5 A V 1 20 100 VTH - 1.8% VTH - 3% MIN 0.7 1.0 0.78 1.2 4 5 VTH VTH 30 1.5 30 150 2 40 200 0.4 0.3 0.4 V V ms TYP MAX 5.5 5.5 5.5 5.5 10 12 VTH + 1.8% V VTH + 3% s A V UNITS
Reset Threshold
VTH
MAX680_UR_ _D_-T, Table 1
VOH
RESET Output Voltage (MAX6800)
VOH
VOL RESET Output Leakage Current (MAX6802)
VCC > VTH, RESET not asserted
Note 1: All parts are production tested at TA = +25C. 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 50A.
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3-Pin, Low-Power P Reset Circuits
Typical Operating Characteristics
(Reset not asserted, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX6800/01/02 toc01
MAX6800/MAX6801/MAX6802
NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE
MAX6800/01/02 toc02
RESET (VOL) vs. SUPPLY VOLTAGE
+125C OUTPUT VOLTAGE LOW (mV) 60 +85C 40 +25C -40C 20 VTH = 2.93V ISINK = 500A RESET ASSERTED MAX6801/MAX6802
MAX6800/01/02 toc03
6.5 6.0 5.5 VCC = +5.0V ICC (A) 5.0 4.5 4.0 3.5 3.0 -50 -25 0 25 50 75 100 VCC = +3.3V
1.050 NORMALIZED RESET TIMEOUT PERIOD 1.040 1.030 1.020 1.010 1.000 0.990 0.980 0.970 0.960 0.950
80
0 -50 -25 0 25 50 75 100 125 1.0 1.5 2.0 VCC (V) 2.5 3.0 TEMPERATURE (C)
125
TEMPERATURE (C)
RESET (VOH) vs. SUPPLY VOLTAGE
MAX6800/01/02 toc04
MAXIMUM TRANSIENT DURATION vs. RESET COMPARATOR OVERDRIVE
MAX6800/01/02 toc05
VCC FALLING PROPAGATION DELAY vs. TEMPERATURE
90 PROPAGATION DELAY (s) 80 70 60 50 40 30 20 10 0 VCC = FALLING AT 10V/ms VCC = FALLING AT 1V/ms
MAX6800/01/02 toc06
100 OUTPUT VOLTAGE HIGH (VCC - VOH) (mV) VTH = 2.93V ISOURCE = 100A RESET ASSERTED (MAX6800)
600 MAXIMUM TRANSIENT DURATION (s) 500 400 300 200 100 0 RESET DOES NOT OCCUR RESET OCCURS
100
75
50
+125C +85C +25C
25 -40C 0 1.0 1.5 2.0 VCC (V) 2.5 3.0
0.1
100 1000 RESET COMPARATOR OVERDRIVE (mV)
1
10
-50
-25
0
25
50
75
100
125
TEMPERATURE (C)
Pin Description
PIN MAX6800 1 -- MAX6801/ MAX6802 1 2 NAME GND RESET Ground 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. 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. Supply Voltage Input FUNCTION
2 3
-- 3
RESET VCC
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3-Pin, Low-Power P Reset Circuits MAX6800/MAX6801/MAX6802
Applications Information
Interfacing to Ps with Bidirectional Reset Pins
Since the RESET output on the MAX6802 is open-drain, this device interfaces easily with Ps that have bidirectional reset pins, such as the Motorola 68HC11. Connecting the P supervisor's RESET output directly to the microcontroller's (C'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 P 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 100k VCC P MOTOROLA 68HCXX RESET GND
VCC
VCC
100k* MAX6801
RESET
MAX6800
RESET
MAX6802
RESET GND
GND
100k (b)
GND
(a) Figure 1. Interfacing to Ps with Bidirectional Reset Pins
*ASSUMES HIGH-Z RESET INPUT TO THE P
Figure 2. Ensuring Reset Valid Down to VCC = 0
Pin Configuration
TOP VIEW
GND 1 VCC
Typical Operating Circuit
VCC
VCC
MAX6800 MAX6801 MAX6802
3 VCC
MAX6801
RESET RESET
P
RESET (RESET) 2
GND
GND
SOT23-3
( ) ARE FOR MAX6800
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3-Pin, Low-Power P Reset Circuits
Ensuring a Valid Reset Output Down to VCC = 0
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 Ps 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; 100k 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 100k 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.
MAX6800/MAX6801/MAX6802
Table 1. Factory-Trimmed Reset Thresholds
RESET THRESHOLD SUFFIX 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 TA = +25C MIN 4.714 4.615 4.547 4.419 4.301 4.223 4.124 4.026 3.928 4.830 3.732 3.633 3.535 3.437 3.339 3.241 3.142 3.025 2.946 2.877 2.750 2.651 2.583 TYP (VTH) 4.80 4.70 4.63 4.50 4.38 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40 3.30 3.20 3.08 3.00 2.93 2.80 2.70 2.63 MAX 4.886 4.785 4.713 4.581 4.459 4.377 4.276 4.174 4.072 3.970 3.868 3.767 3.665 3.563 3.461 3.359 3.258 3.135 3.054 2.983 2.850 2.749 2.677 TA = -40C to +125C MIN 4.656 4.559 4.491 4.365 4.249 4.171 4.074 3.977 3.880 3.783 3.686 3.589 3.492 3.395 3.298 3.201 3.104 2.988 2.910 2.842 2.716 2.619 2.551 MAX 4.944 4.841 4.769 4.635 4.511 4.429 4.326 4.223 4.120 4.017 3.914 3.811 3.708 3.605 3.502 3.399 3.296 3.172 3.090 3.018 2.884 2.781 2.709
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3-Pin, Low-Power P Reset Circuits MAX6800/MAX6801/MAX6802
Selector Guide (Standard Versions*)
PART MAX6800UR26D3-T MAX6800UR29D3-T MAX6800UR31D3-T MAX6800UR44D3-T MAX6800UR46D3-T MAX6801UR26D3-T MAX6801UR29D3-T MAX6801UR31D3-T MAX6801UR44D3-T MAX6801UR46D3-T MAX6802UR26D3-T MAX6802UR29D3-T MAX6802UR31D3-T MAX6802UR44D3-T MAX6802UR46D3-T OUTPUT STAGE Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Push/Pull RESET Open-Drain RESET Open-Drain RESET Open-Drain RESET Open-Drain RESET Open-Drain RESET NOMINAL VTH (V) 2.63 2.93 3.08 4.38 4.63 2.63 2.93 3.08 4.38 4.63 2.63 2.93 3.08 4.38 4.63 MIN RESET TIMEOUT (ms) 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 SOT TOP MARK FZIE FZIF FZIG FZIH FZII FZIK FZIM FZIN FZIO FZIP FZIQ FZIR FZIS FZIT FZIU
*Sample stock is generally held on all standard versions.
Chip Information
TRANSISTOR COUNT: 505 PROCESS: BiCMOS
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3-Pin, Low-Power P Reset Circuits
Package Information
SOTPO3L.EPS
MAX6800/MAX6801/MAX6802
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 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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