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19-1946; Rev 1; 2/01
4-Pin, Low-Power P Reset Circuits with Manual Reset
General Description
The MAX6803/MAX6804/MAX6805 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. They also feature a debounced manual reset input. These devices perform a single function: they assert a reset signal whenever the VCC supply voltage declines below a preset threshold or whenever manual reset is asserted. Reset remains asserted for a preset timeout period after VCC has risen above the reset threshold or after manual reset is deasserted. The only difference among the three devices is their output. The MAX6804 (push/pull) and MAX6805 (open-drain) have an activelow RESET output, while the MAX6803 (push/pull) has an active-high RESET output. The MAX6803/MAX6804 are guaranteed to be in the correct state for VCC down to 0.7V. The MAX6805 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 timeout period. Ideal for space-critical applications, the MAX6803/ MAX6804/MAX6805 come packaged in a 4-pin SOT143. For a lower threshold voltage version, see the MAX6335/MAX6336/MAX6337. 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 Debounced Manual Reset Input 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 (MAX6803/MAX6804) o Power-Supply Transient Immunity o No External Components Required o 4-Pin SOT143 Package o Pin Compatible with MAX811/MAX812 and MAX6314/MAX6315
Features
o Ultra-Low 0.7V Operating Supply Voltage
MAX6803/MAX6804/MAX6805
Applications
Computers Controllers Intelligent Instruments Critical P/C Power Monitoring Portable/Battery-Powered Equipment Automotive
PART*
MAX6803US_ _D_-T MAX6804US_ _D_-T MAX6805US_ _D_-T
Ordering Information
TEMP. RANGE -40C to +125C -40C to +125C -40C to +125C PIN-PACKAGE 4 SOT143 4 SOT143 4 SOT143
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 "US" 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
1
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4-Pin, Low-Power P Reset Circuits with Manual Reset MAX6803/MAX6804/MAX6805
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND) VCC ......................................................................-0.3V to +6V Push/Pull RESET or RESET, MR ............-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) 4-Pin SOT143 (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 1) SYMBOL CONDITIONS TA = 0C to +125C VCC TA = -40C to +125C Supply Current ICC No load MAX6803/MAX6804 MAX6805 MAX6803/MAX6804 MAX6805 VCC = +3.0V VCC = +5.0V TA = +25C TA = -40C to +125C VCC Falling Reset Delay Reset Active Timeout Period MR Minimum Pulse Width MR Glitch Immunity MR Reset Delay MR Input Voltage MR Pullup Resistance RESET Output Low Voltage (MAX6804/MAX6805) RESET Output High Voltage (MAX6804) VOL Reset asserted Reset not asserted ISINK = 50A, VCC 1.0V ISINK = 1.2mA, VCC 2.5V ISINK = 3.2mA, VCC 4.25V ISOURCE = 500A, VCC 3.0V ISOURCE = 800A, VCC 5.0V 0.8 VCC 0.8 VCC VIL VIH 0.7 VCC 12 20 30 0.4 0.3 0.4 V V tRP VCC falling at 10V/ms MAX680_US_ _D1-T MAX680_US_ _D2-T MAX680_US_ _D3-T 1 20 100 1 50 0.1 0.3 VCC 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 s ns s V k 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_US_ _D_-T, Table 1
VOH
2
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4-Pin, Low-Power P Reset Circuits with Manual Reset
ELECTRICAL CHARACTERISTICS (continued)
(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 SYMBOL VOH Reset asserted Reset not asserted CONDITIONS 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 MIN 0.8 VCC 0.8 VCC 0.8 VCC 0.3 0.4 0.5 V A V TYP MAX UNITS
MAX6803/MAX6804/MAX6805
RESET Output Voltage (MAX6803)
VOL RESET Output Leakage Current (MAX6805)
VCC > VTH, RESET not asserted
Note 1: All parts are production tested at TA = +25C. Over temperature limits are guaranteed by design and not production tested. Note 2: ISOURCE for the MAX6803 is 100nA; ISINK for the MAX6804 is 100nA; ISINK for the MAX6805 is 50A.
__________________________________________Typical Operating Characteristics
(Reset not asserted, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX6803/04/05 toc01
NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE
MAX6803/04/05 toc02
OUTPUT VOLTAGE LOW vs. SUPPLY VOLTAGE
VTH = 2.93V ISINK = 500A RESET +125C 40 +85C +25C -40C 20
MAX6803/04/05 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
OUTPUT VOLTAGE LOW (mV)
60
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)
OUTPUT VOLTAGE HIGH vs. SUPPLY VOLTAGE
OUTPUT VOLTAGE HIGH (VCC - VOH) (mV) MAXIMUM TRANSIENT DURATION (s) VTH = 2.93V ISINK = 100A RESET ASSERTED (MAX6803)
MAX6803/04/05 toc04
MAXIMUM TRANSIENT DURATION vs. RESET COMPARATOR OVERDRIVE
MAX6803/04/05 toc05
VCC FALLING PROPAGATION DELAY vs. TEMPERATURE
90 POROPAGATION DELAY (s) 80 70 60 50 40 30 20 10 0 VCC = FALLING AT 10V/ms VCC = FALLING AT 1V/ms
MAX6803/04/05 toc06
100
600 500 400 300 200 100 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)
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4-Pin, Low-Power P Reset Circuits with Manual Reset MAX6803/MAX6804/MAX6805
Pin Description
PIN MAX6803 1 MAX6804 MAX6805 1 NAME GND Ground Active-Low Reset Output. RESET is asserted while VCC is below the reset threshold, or while MR is asserted. RESET remains asserted for a reset timeout period (tRP) after VCC rises above the reset threshold or MR is deasserted. RESET on the MAX6804 is push/pull. RESET on the MAX6805 is open-drain. Active-High Reset Output. RESET is asserted high while VCC is below the reset threshold or while MR is asserted, and RESET remains asserted for a reset timeout period (tRP) after VCC rises above the reset threshold or MR is deasserted. RESET on the MAX6803 is push/pull. Manual Reset Input. A logic low on MR asserts reset. Reset remains asserted as long as MR is low, and for the reset timeout period (tRP) after MR goes high. Leave unconnected or connect to VCC if not used. Supply Voltage Input FUNCTION
--
2
RESET
2
--
RESET
3 4
3 4
MR VCC
Applications Information
Manual Reset Input
Many P-based products require manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. A logic low on MR asserts reset. Reset remains asserted while MR is low, and for the reset active timeout period after MR returns high. MR has an internal 20k pullup resistor, so it can be left unconnected if not used. Connect a normally open momentary switch from MR to GND to create a manual reset function; external debounce circuitry is not required.
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.
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
VCC VCC 100k VCC P MOTOROLA 68HCXX RESET
Interfacing to Ps with Bidirectional Reset Pins
Since the RESET output on the MAX6805 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).
MAX6805
MR RESET
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 V CC transients (glitches). The Typical Operating Characteristics show the Maximum Transient Duration vs. Reset Comparator Overdrive graph. The graph
4
GND
GND
Figure 1. Interfacing to Ps with Bidirectional Reset Pins
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4-Pin, Low-Power P Reset Circuits with Manual Reset
Ps and circuitry do not operate when VCC drops below 1V. For the MAX6804 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 MAX6803, 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 MAX6805 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.
MAX6803/MAX6804/MAX6805
VCC
Pin Configuration
TOP VIEW
MAX6804
MR RESET GND 1 4 VCC
(a)
GND
100k
MAX6803 MAX6804 MAX6805
VCC RESET (RESET) 2 3 MR
100k* MAX6803
MR RESET ( ) ARE FOR MAX6803
SOT143
(b)
GND
*ASSUMES HIGH-Z RESET INPUT TO THE P
Typical Operating Circuit
VCC
Figure 2. Ensuring Reset Valid down to VCC = 0
VCC
VCC
MAX6804
MR RESET RESET
P
GND
GND
PUSHBUTTON SWITCH
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4-Pin, Low-Power P Reset Circuits with Manual Reset MAX6803/MAX6804/MAX6805
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 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 TA = -40C to +125C 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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4-Pin, Low-Power P Reset Circuits with Manual Reset
Selector Guide (Standard Versions*)
PART MAX6803US26D3-T MAX6803US29D3-T MAX6803US31D3-T MAX6803US44D3-T MAX6803US46D3-T MAX6804US26D3-T MAX6804US29D3-T MAX6804US31D3-T MAX6804US44D3-T MAX6804US46D3-T MAX6805US26D3-T MAX6805US29D3-T MAX6805US31D3-T MAX6805US44D3-T MAX6805US46D3-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 KACH KACI KACJ KACK KACL KACN KACP KACQ KACR KACS KACO KACU KACV KACW KACX
MAX6803/MAX6804/MAX6805
*Sample stock is generally held on all standard versions.
Chip Information
TRANSISTOR COUNT: 505 PROCESS: BiCMOS
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4-Pin, Low-Power P Reset Circuits with Manual Reset MAX6803/MAX6804/MAX6805
Package Information
SOT1434.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.
8 _____________________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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