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19-2242; Rev 1; 1/02
Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits
General Description
The MAX6832-MAX6840 are microprocessor (P) supervisory circuits used to monitor low-voltage power supplies in P and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with +1.2V to +1.8V powered circuits. These devices assert a reset signal whenever the VCC supply voltage declines below a preset threshold or whenever manual reset (MR) is asserted. Reset remains asserted for a fixed timeout delay after VCC has risen above the reset threshold or when manual reset is deasserted. Five different timeout periods are available: 70s (voltage detector), 1.5ms, 30ms, 210ms, and 1.68s. Reset thresholds suitable for operation with a variety of supply voltages are available. The MAX6832/MAX6835/MAX6838 have a push-pull active-low reset output (RESET). The MAX6833/ MAX6836/MAX6839 have a push-pull active-high reset output (RESET) and the MAX6834/MAX6837/MAX6840 have an open-drain active-low reset output (RESET). The open-drain active-low reset output requires a pullup resistor that can be connected to a voltage higher than VCC. The MAX6835/MAX6836/MAX6837 feature a debounced manual reset input (MR), while the MAX6838/MAX6839/ MAX6840 provide a RESET-IN input allowing the user to externally adjust the reset threshold. The reset comparator is designed to ignore fast transients on VCC. Low supply current of 7.5A makes the MAX6832- MAX6840 ideal for use in portable equipment. These devices are available in 3- and 4-pin SC70 packages.
Features
o Factory-Set Reset Threshold Voltages for Nominal Supplies from 1.2V to 1.8V o Low Power Consumption: 7.5A (typ) o Space-Saving 3- and 4-Pin SC70 Packages o 2.5% Reset Threshold Accuracy Over Temperature o Five Different Timeout Periods Available: 70s (voltage detector), 1.5ms, 30ms, 210ms, and 1.68s o Three Reset Output Configurations Push-Pull RESET Push-Pull RESET Open-Drain RESET o Guaranteed Reset Valid to VCC = 0.55V--Active-Low 0.75V--Active-High o Adjustable Threshold Reset-In Option o Manual Reset Input Option o Immune to Short Negative VCC Transients o Pin Compatible with MAX803/MAX809/MAX810, MAX6711/MAX6712/MAX6713, and MAX6381-MAX6390 Series
MAX6832-MAX6840
Ordering Information
PART MAX6832_XRD_-T MAX6833_XRD_-T MAX6834_XRD_-T MAX6835_XSD_-T MAX6836_XSD_-T MAX6837_XSD_-T MAX6838XSD_-T MAX6839XSD_-T MAX6840XSD_-T TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 3 SC70-3 3 SC70-3 3 SC70-3 4 SC70-4 4 SC70-4 4 SC70-4 4 SC70-4 4 SC70-4 4 SC70-4
Applications
Computers Controllers Intelligent Instruments Critical P and C Power Monitoring Portable/Battery-Powered Equipment
Pin Configurations appear at end of data sheet. Typical Operating Circuit apears at end of data sheet. Selector Guide appears at end of data sheet.
Insert the desired suffix letter from the Threshold Suffix Guide (MAX6832-MAX6837) and the Active Timeout Period Guide tables into the blanks to complete the part number. Sample stock is generally available on standard versions only (see Standard Versions table). Standard versions require a minimum order increment of 2.5k units. Nonstandard versions must be ordered in 10k unit increments. Contact factory for availability. All parts are offered in tape-and-reel only.
________________________________________________________________ Maxim Integrated Products
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits MAX6832-MAX6840
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND) VCC ........................................................................-0.3V to +6.0V Open-Drain RESET, MR .......................................-0.3V to +6.0V RESET-IN, Push-Pull RESET and RESET ..............................................-0.3V to (VCC + 0.3V) Input/Output Current (all pins) ............................................20mA Continous Power Dissipation (TA = +70C) 3-Pin SC70 (derate 2.9mW/C above +70C) ...............235mW 4-Pin SC70 (derate 3.1mW/C above +70C) ...............245mW Operating Temperature Range ...........................-40C to +85C 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 = +0.55V to +3.6V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS TA = -40C to +85C MAX6832/MAX6835/MAX6838 MAX6834/MAX6837/MAX6840 Supply Voltage Range VCC TA = -40C to +85C MAX6833/MAX6836/MAX6839 TA = 0C to +85C MAX6833/MAX6836/MAX6839 VCC = 1.2V, no load, reset not asserted Supply Current ICC VCC = 1.8V, no load, reset not asserted VCC = 3.6V, no load, reset not asserted W V Reset Threshold VTH I H G F (Note 2) RESET-IN Threshold RESET-IN Leakage Current Reset Threshold Hysteresis VCC or RESET-IN to Reset Delay VRSTIN IRSTIN VHYS VCC falling, step signal from (VTH + 100mV) to (VTH - 100mV) D0 D1 Reset Active Timeout Period tRP D2 D3 D4 1 20 140 1120 1.1V VCC 3.3V, 0C to +85C 1.1V VCC 3.3V, -40C to +85C 1.620 1.530 1.350 1.275 1.080 1.020 -2.5% -3.0% -25 0.75 60 0.07 1.5 30 210 1680 2 40 280 2240 ms MIN 0.55 TYP MAX 3.6 V UNITS
0.85 0.75 7.5 9 16 1.665 1.575 1.388 1.313 1.110 1.050 444 444
3.6 3.6 13 16 25 1.710 1.620 1.425 1.350 1.140 1.080 +2.5% +3.0% +25
A
V
mV nA %VTH s
2
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +0.55V to +3.6V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Propagation Delay (D0 only) Startup Time (D0 only) MR Input Voltage MR Minimum Input Pulse Width MR Glitch Rejection MR to Reset Delay MR Pullup Resistance To VCC Open-Drain RESET Output Voltage Open-Drain RESET Output Leakage Current VCC 0.55V, ISINK =15A, reset asserted VOL VCC 1.0V, ISINK = 80A, reset asserted VCC 1.5V, ISINK = 200A, reset asserted ILKG VCC > VTH, reset not asserted VCC 0.55V, ISINK = 15A, reset asserted VOL Push-Pull RESET Output Voltage VOH VCC 1.0V, ISINK = 80A, reset asserted VCC 1.5V, ISINK = 200A, reset asserted VCC 1.1V, ISOURCE = 50A, reset not asserted VCC 1.5V, ISOURCE = 150A, reset asserted VCC 0.75V, ISOURCE = 10A, reset asserted (Note 2) Push-Pull RESET Output Voltage VOH VCC 0.85V, ISOURCE = 10A, reset asserted VCC 1.0V, ISOURCE = 50A, reset asserted VCC 1.5V, ISOURCE = 150A, reset asserted VOL VCC 1.1V, ISINK = 80A, reset not asserted VCC 1.5V, ISINK = 200A, reset not asserted 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.8 x VCC 0.2 x VCC 0.2 x VCC V VIL VIH MR driven from VCC to 0 MR driven from VCC to 0 MR driven from VCC to 0 14 0.7 x VCC 2 100 500 20 26 0.15 0.15 0.2 1.0 0.2 x VCC 0.2 x VCC 0.2 x VCC A V SYMBOL tP CONDITIONS VCC rising, step signal from (VTH - 100mV) to (VTH + 100mV) VCC rising from 0 to 1.1V (tR < 1s) MIN TYP 70 150 0.3 x VCC MAX UNITS s s V s ns ns k
MAX6832-MAX6840
Note 1: 100% production tested at +25C. Over temperature limits are guaranteed by design. Note 2: Temperature range is from 0C to +85C.
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits MAX6832-MAX6840
Typical Operating Characteristics
(VCC = full range and TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C).
POWER-DOWN RESET DELAY vs. TEMPERATURE
MAX6832-40 toc01
SUPPLY CURRENT vs. TEMPERATURE
16 VCC = 3.6V 14 VCC = 3.0V SUPPLY CURRENT (A) 12 10 8 6 4 2 0 -40 -20 40 TEMPERATURE (C) 0 20 60 80 VCC = 0.55V 0 -40 VCC = 2.5V VCC = 1.8V VCC = 1.5V 300 POWER-DOWN RESET DELAY (s) 250 200
VOD = OVERDRIVE (mV)
VOD = 10mV 150 VOD = 20mV 100 50 VOD = 100mV VOD = 200mV -20 0 20 40 60 80
TEMPERATURE (C)
NORMALIZED POWER-UP RESET TIMEOUT vs. TEMPERATURE
MAX6832-40 toc03
NORMALIZED RESET THRESHOLD vs. TEMPERATURE
VTH = 1.665V 1.002 1.001 1.000 0.999 0.998 0.997 0.996 0.995
MAX6832-40 toc04
1.06 NORMALIZED RESET TIMEOUT PERIOD 1.04 1.02 1.00 D2 OPTION 0.98 0.96 0.94 -40 -20 0 20 40 60 80 TEMPERATURE (C) D1 OPTION
1.003 NORMALIZED RESET THRESHOLD
0.994 -40 -20 0 20 40 60 80 TEMPERATURE (C)
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MAX6832-40 toc02
Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits
Pin Description--MAX6832-MAX6837
PIN MAX6833 SC70-3 1 MAX6832/ MAX6834 SC70-3 1 MAX6836 SC70-4 1 MAX6835/ MAX6837 SC70-4 1 NAME FUNCTION
MAX6832-MAX6840
GND
Ground Reset Output, Open-Drain or Push-Pull, Active-Low. RESET changes from HIGH to LOW when VCC drops below the selected reset threshold or MR is pulled low. RESET remains LOW for the reset timeout period after VCC exceeds the device reset threshold and MR is released high. Reset Output, Push-Pull, Active-High. RESET changes from LOW to HIGH when the VCC input drops below the selected reset threshold or MR is pulled low. RESET remains HIGH for the reset timeout period after VCC exceeds the device reset threshold and MR is released high. Active-Low Manual Reset Input. Internal 20k pullup to VCC. Pull LOW to force a reset. Reset remains active as long as MR is LOW and for the reset timeout period after MR goes HIGH. Leave unconnected or connect to VCC if unused. Supply Voltage and Monitored Supply
--
2
--
2
RESET
2
--
2
--
RESET
--
--
3
3
MR
3
3
4
4
VCC
Pin Description--MAX6838/MAX6839/MAX6840
PIN MAX6839 SC70-4 MAX6838/ MAX6840 SC70-4 NAME FUNCTION
1
1
RESET-IN
Adjustable Reset Threshold Input. High-impedance input for reset comparator. Connect this pin to an external resistive-divider network to set the reset threshold voltage; the typical threshold is 444mV. Reset is asserted when RESET-IN is below the threshold (VCC is not monitored). Supply Voltage (1.1V to 3.3V) Ground Reset Output, Push-Pull, Active-High. RESET changes from LOW to HIGH when the RESET-IN input drops below the typical reset threshold (444mV). RESET remains HIGH for the reset timeout period after RESET-IN exceeds the reset threshold. Reset Output, Open-Drain or Push-Pull, Active-Low. RESET changes from HIGH to LOW when RESET-IN drops below the typical reset threshold (444mV). RESET remains LOW for the reset timeout period after RESET-IN exceeds the reset threshold.
2 3 4
2 3 --
VCC GND RESET
--
4
RESET
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits MAX6832-MAX6840
Functional Diagrams
MR (MAX6835/MAX6836/MAX6837 ONLY)
VCC MR PULLUP MANUAL RESET DETECT
VCC
RESET-IN RESET TIMEOUT PERIOD RESET OUTPUT RESET/ RESET RESET OUTPUT RESET/ RESET
RESET TIMEOUT PERIOD
VREF = 444mV
VREF = 444mV
MAX6832- MAX6837
MAX6838/ MAX6839/ MAX6840
GND
GND
Detailed Description
Reset Output
A microprocessor's (P's) reset input starts the P in a known state. The MAX6832-MAX6840 assert a reset to prevent code-execution errors during power-up, powerdown, or brownout conditions. They also assert a reset signal whenever the VCC supply voltage falls below a preset threshold (MAX6832-MAX6837) or RESET-IN falls below the adjustable threshold (MAX6838/ MAX6839/MAX6840), keeping reset asserted for a fixed timeout delay (Table 2) after VCC or RESET-IN has risen above the reset threshold. The MAX6832/MAX6835/ MAX6838 use a push-pull active-low output, the MAX6833/MAX6836/MAX6839 have a push-pull activehigh output, and the MAX6834/MAX6837/MAX6840 have an open-drain active-low output stage. Connect a pullup resistor on the MAX6834/MAX6837/MAX6840's RESET output to any supply between 0 and 6V.
MR is driven from long cables or if the device is used in a noisy environment, connecting a 0.1F capacitor from MR to ground provides additional noise immunity.
RESET-IN Information
The MAX6838/MAX6839/MAX6840 feature a RESET-IN input for monitoring supply voltages down to 0.44V. An external resistive-divider network can be used to set voltage monitoring thresholds as shown in Figure 1. As the monitored voltage falls, the voltage at RESET-IN decreases and asserts a reset when it falls below the RESET-IN threshold (VRSTIN). The low-leakage current
VMONITORED
MAX6838/ MAX6839/ MAX6840
VCC
R1 RESET-IN R2 GND ( ) ARE FOR MAX6839 R1 = R2 [(VMONITORED/VREF) -1] WHERE VMONITORED IS THE DESIRED TRIP LEVEL, VREF = 444mV RESET (RESET)
Manual Reset Input
Many P-based systems require manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset. Reset remains asserted while MR is low, and for a fixed timeout delay after MR returns high. This input has an internal 20k pullup resistor, so it can be left open if it is not used. MR can be driven with CMOS logic level, or with open-drain/collector outputs. To create a manual reset function, connect a normally open momentary switch from MR to ground; external debounce circuitry is not required. If
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Figure 1. Setting the Adjustable Threshold Externally
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits
at RESET-IN allows for relatively large-value resistors to be used, which reduce power consumption. For example, for a 0.6V monitored trip level, if R2 = 200k, then R1 = 70.3k. Note that the minimum VCC of 1.1V is required to guarantee the RESET-IN threshold accuracy (see Electrical Characteristics table). can drift to undetermined voltages. This presents no problem in most applications since most P and other circuitry are inoperative with VCC lower than 0.55V. However, in applications where RESET must be valid down to 0, adding a pulldown resistor to RESET causes any stray leakage currents to flow to ground, holding RESET low (Figure 3). R3's value is not critical; 100k is large enough not to load RESET and small enough to pull RESET to ground. A 100k pullup resistor to VCC is also recommended for the MAX6833/MAX6836/MAX6839 if RESET is required to remain valid for VCC < 0.85V.
MAX6832-MAX6840
Applications Information
Negative-Going VCC Transients In addition to issuing a reset to the P during power-up, power-down, and brownout conditions, the MAX6832- MAX6840 are relatively immune to short-duration negative-going VCC transients (glitches). Figure 2 shows typical transient duration vs. reset comparator overdrive, for which the MAX6832-MAX6840 do not generate a reset pulse. The graph was generated using a negative-going pulse applied to VCC, starting 0.1V 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 farther below the reset threshold), the maximum allowable pulse width decreases. A 0.1F bypass capacitor mounted as close as possible to the VCC pin provides additional transient immunity. Ensuring a Valid Reset Output Down to VCC = 0
When VCC falls below 0.55V, the MAX6832/MAX6835/ MAX6838 push-pull RESET output no longer sinks current--it becomes an open circuit. Therefore, highimpedance CMOS logic inputs connected to RESET
MAXIMUM TRANSIENT DURATION vs. OVERDRIVE
900 MAXIMUM TRANSIENT DURATION (s) 800 700 600 500 400 300 200 100 0 1 10 OVERDRIVE VTH - VCC (mV) 100 RESET OCCURS ABOVE THIS LINE
VCC
MAX6832 MAX6835 RESET MAX6838
GND R3 100k
Figure 3. RESET Valid to VCC = Ground Circuit
Interfacing to Ps with Bidirectional Reset Pins
Since the RESET output on the MAX6834/MAX6837/ MAX6840 is open-drain, these devices interface easily with Ps that have bidirectional reset pins. Connecting the P supervisor's RESET output directly to the P's RESET pin with a single pullup resistor allows either device to assert a reset (Figure 4).
VCC
VCC
VCC
MAX6834 MAX6837 MAX6840 RESET
RESET INPUT
BIDIRECTIONAL P
GND
GND
Figure 2. Maximum Transient Duration Without Causing a Reset Pulse vs. Reset Comparator Overdrive
Figure 4. Interfacing to Ps with Bidirectional Reset I/O 7
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits MAX6832-MAX6840
Using The MAX6834/MAX6837/MAX6840 Open-Drain RESET Output with Multiple Supplies
Generally, the pullup connected to the MAX6834/ MAX6837/MAX6840 will connect to the supply voltage that is being monitored at the IC's VCC pin. However, some systems may use the open-drain output to levelshift from the monitored supply to reset circuitry powered by some other supply (Figure 5). Note that as the MAX6834/MAX6837/MAX6840's V CC decreases, so does the IC's ability to sink current at RESET. Also, with any pullup, RESET will be pulled high as VCC declines toward 0. The voltage where this occurs depends on the pullup resistor value and the voltage to which it is connected.
Selector Guide
Table 1. Threshold Suffix Guide
SUFFIX W V I H G F RESET THRESHOLD (V) 1.665 1.575 1.388 1.313 1.110 1.050
Table 2. Active Timeout Period Guide
SUFFIX TYPICAL RESET ACTIVE TIMEOUT PERIOD (ms) 0.07 1.5 30 210 1680
+1.2V
+5.0V
D0 D1 D2 D3
5V SYSTEM
RESET INPUT
VCC RPULLUP
VCC
D4
MAX6834 MAX6837 MAX6840 RESET
Table 3. Standard Versions
DEVICE MAX6832VXRD0 TOP MARK AIQ AIR AIS AIT AIU AIV AHJ AIW AIX AIY AIZ AJA AJB AJC AJD AJE AJF AJG AEX
GND
GND
MAX6832VXRD3 MAX6832HXRD0 MAX6832HXRD3 MAX6832FXRD0 MAX6832FXRD3 MAX6833VXRD0 MAX6833VXRD3 MAX6833HXRD0 MAX6833HXRD3 MAX6833FXRD0 MAX6833FXRD3 MAX6834VXRD0 MAX6834VXRD3 MAX6834HXRD0 MAX6834HXRD3 MAX6834FXRD0 MAX6834FXRD3 MAX6835VXSD0
Figure 5. Using The MAX6834/MAX6837/MAX6840 Open-Drain RESET Output with Multiple Supplies
Chip Information
TRANSISTOR COUNT: 681 PROCESS: BiCMOS
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits
Pin Configurations
TOP VIEW
MAX6832-MAX6840
GND
1
GND
1
4
VCC
RESET-IN
1
4
RESET (RESET)
RESET (RESET)
2
MAX6832 MAX6833 MAX6834
3
VCC RESET (RESET) 2
MAX6835 MAX6836 MAX6837
3
MR
VCC
2
MAX6838 MAX6839 MAX6840
3
GND
SC70-3
( ) ARE FOR MAX6833
SC70-4
( ) ARE FOR MAX6836
SC70-4
( ) ARE FOR MAX6839
Typical Operating Circuit
VIN 3.3V 1.2V DC/DC CONVERTER VCC RESET CORE SUPPLY RESET I/O SUPPLY
Selector Guide (continued)
Table 3. Standard Versions (continued)
DEVICE MAX6835VXSD3 MAX6835HXSD0 MAX6835HXSD3 MAX6835FXSD0 MAX6835FXSD3 MAX6836VXSD0 MAX6836VXSD3 MAX6836HXSD0 MAX6836HXSD3 MAX6836FXSD0 MAX6836FXSD3 MAX6837VXSD0 MAX6837VXSD3 MAX6837HXSD0 MAX6837HXSD3 MAX6837FXSD0 MAX6837FXSD3 MAX6838XSD0 MAX6838XSD3 MAX6839XSD0 MAX6839XSD3 MAX6840XSD0 MAX6840XSD3 TOP MARK AFF AFG AFH AFI AFJ AFK AFL AFM AFN AFO AFP AFQ AFR AFS AFT AFU AFC AFW AFV AFX AEZ AFY AFZ
P GND
MAX6834G/F
GND
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits MAX6832-MAX6840
Package Information
SC70, 3L.EPS
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Ultra-Low-Voltage SC70 Voltage Detectors and P Reset Circuits
Package Information (continued)
SC70, 4L.EPS
MAX6832-MAX6840
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 ____________________ 11 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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