View MAX6830UT-T_4879992.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-1867; Rev 2; 12/05
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer
General Description
The MAX6826-MAX6831 are ultra-low-voltage microprocessor (P) supervisory circuits designed to monitor two power supplies and have manual reset and watchdog input functions. These devices assert a system reset if any of the monitored supplies fall below the preprogrammed thresholds, and maintain reset for a minimum timeout period after the supplies rise above the threshold. Microprocessor supervisors significantly improve system reliability and accuracy compared to separate ICs or discrete components. These devices monitor primary voltages from +1.8V to +5.0V and secondary voltages from +0.9V to +2.5V. These devices are guaranteed to be in the correct state for VCC down to +1.0V. A variety of preprogrammed reset threshold voltages are available (see the Threshold Suffix Guide). The devices include manual reset and watchdog inputs. The MAX6829/MAX6830/MAX6831 provide a factorytrimmed threshold to monitor a 2nd voltage down to +0.9V. The MAX6826/MAX6829 have a push-pull RESET, the MAX6827/MAX6830 have a push-pull RESET and the MAX6828/MAX6831 have an open-drain RESET. The MAX6826/MAX6827/MAX6828 have an auxiliary monitor that allows user adjustable input to monitor voltages down to +0.6V. See Selector Guide for functions available.
Features
Monitor Primary VCC Supplies from +1.8V to +5.0V and Secondary VCC2 Supplies from +0.9V to +2.5V User Adjustable RESET IN Down to +0.63V (MAX6826/MAX6827/MAX6828) 140ms (min) Reset Timeout Delay 1.6s Watchdog Timeout Period Manual Reset Input Three Reset Output Options Push-Pull RESET Push-Pull RESET Open-Drain RESET Guaranteed Reset Valid Down to VCC = +1.0V Immune to Short Negative VCC Transients No External Components Small 6-pin SOT23 Packages
MAX6826-MAX6831
Ordering Information
PART MAX6826_UT-T MAX6827_UT-T MAX6828_UT-T MAX6829_ _UT-T MAX6830_ _UT-T MAX6831_ _UT-T TEMP RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C PIN-PACKAGE 6 SOT23-6 6 SOT23-6 6 SOT23-6 6 SOT23-6 6 SOT23-6 6 SOT23-6
________________________Applications
Portable/BatteryPowered Equipment Embedded Controllers Intelligent Instruments Automotive Systems Critical P Monitoring Multivoltage Systems
Insert the desired suffix letter (from Standard Versions table) into
Pin Configuration
TOP VIEW
RESET(RESET) 1 6 VCC
the blanks to complete the part number. Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing "-T" with "+T" when ordering.
Standard Versions Table*
MAX6826/MAX6827/MAX6828 L S R Z V
GND 2
MAX6826- MAX6831
5
RESET IN/VCC2
MR 3
4
WDI
SOT23-6
(RESET) MAX6827/MAX6830 ONLY RESET IN FOR MAX6826/MAX6827/MAX6828 ONLY VCC2 FOR MAX6829/MAX6830/MAX6831 ONLY
*Samples are typically available for standard versions only. The MAX6826/MAX6827/MAX6828 require a 2.5k minimum order increment for all versions. Contact factory for availability. Standard Versions Table continued at end of data sheet.
Typical Operating Circuit, Threshold Suffix Guide, and Selector Guide appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
ABSOLUTE MAXIMUM RATINGS
VCC, VCC2 to GND.................................................-0.3V to +6.0V Open-Drain RESET................................................-0.3V to +6.0V Push-Pull RESET, RESET............................-0.3V to (VCC + 0.3V) MR, WDI, RESET IN....................................-0.3V to (VCC + 0.3V) Input Current (VCC) .............................................................20mA Output Current (RESET, RESET).........................................20mA Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C)..............696mW 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 = +4.5V to +5.5V for MAX68_ _L/M, VCC = +2.7V to +3.6V for MAX68_ _T/S/R, VCC = +2.1V to +2.75V for MAX68_ _Z/Y, VCC = +1.53V to +2.0V for MAX68_ _W/V; TA = -40C to +125C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER Operating Voltage Range SYMBOL VCC CONDITIONS TA = 0C to +85C TA = -40C to +125C VCC = +5.5V, no load ICC VCC = +3.6V, no load VCC2 +2.5V MAX68_ _L MAX68_ _M MAX68_ _T MAX68_ _S VCC Reset Threshold (VCC Falling) VTH MAX68_ _R MAX68_ _Z MAX68_ _Y MAX68_ _W MAX68_ _V TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C 4.50 4.47 4.25 4.22 3.00 2.97 2.85 2.83 2.55 2.53 2.25 2.24 2.12 2.11 1.62 1.61 1.52 4.63 4.63 4.38 4.38 3.08 3.08 2.93 2.93 2.63 2.63 2.32 2.32 2.19 2.19 1.67 1.67 1.58 TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C 7 MIN 1.0 1.2 10 TYP MAX 5.5 5.5 20 30 16 25 2 4.75 4.78 4.50 4.53 3.15 3.17 3.00 3.02 2.70 2.72 2.38 2.40 2.25 2.26 1.71 1.72 1.62 V A A UNITS V
VCC Supply Current MR and WDI Unconnected VCC2 Supply Current
2
_______________________________________________________________________________________
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +4.5V to +5.5V for MAX68_ _L/M, VCC = +2.7V to +3.6V for MAX68_ _T/S/R, VCC = +2.1V to +2.75V for MAX68_ _Z/Y, VCC = +1.53V to +2.0V for MAX68_ _W/V; TA = -40C to +125C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER SYMBOL Z Y W V I VCC2 Reset Threshold VTH2 H G F E D Reset Threshold Temperature Coefficient Reset Threshold Hysteresis RESET IN Threshold RESET IN Hysteresis RESET IN Input Current (Note 2) VCC to Reset Output Delay RESET IN to Reset Output Delay Reset Timeout Period tRP IRSTIN tRD TA = -40C to +85C TA = -40C to +125C VCC = VTH to (VTH - 100mV) VRSTIN = VRSTINTH to (VRSTINTH - 30mV) TA = -40C to +85C TA = -40C to +125C VCC 1.0V, ISINK = 50A, reset asserted, TA = 0C to +85C VOL VCC 1.2V, ISINK = 100A, reset asserted VCC 2.55V, ISINK = 1.2mA, reset asserted VCC 4.25V, ISINK = 3.2mA, reset asserted 140 100 -25 -100 20 15 200 280 320 0.3 0.3 0.3 0.4 V VRSTINTH VRSTINTH falling TA = 0C to +85C TA = -40C to +125C 0.615 0.610 2.5 +25 +100 CONDITIONS TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C TA = -40C to +85C TA = -40C to +125C MIN 2.244 2.238 2.119 2.113 1.615 1.611 1.525 1.521 1.346 1.343 1.271 1.268 1.077 1.074 1.017 1.014 0.808 0.806 0.762 0.761 TYP 2.313 2.313 2.188 2.188 1.665 1.665 1.575 1.575 1.388 1.388 1.313 1.313 1.110 1.110 1.050 1.050 0.833 0.833 0.788 0.788 60 2 x VTH 0.630 0.645 0.650 MAX 2.381 2.388 2.257 2.263 1.715 1.719 1.625 1.629 1.429 1.433 1.354 1.358 1.143 1.146 1.083 1.086 0.858 0.860 0.813 0.815 ppm/C mV V mV nA s s ms V UNITS
MAX6826-MAX6831
RESET Output LOW (Push-Pull or Open-Drain)
_______________________________________________________________________________________
3
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +4.5V to +5.5V for MAX68_ _L/M, VCC = +2.7V to +3.6V for MAX68_ _T/S/R, VCC = +2.1V to +2.75V for MAX68_ _Z/Y, VCC = +1.53V to +2.0V for MAX68_ _W/V; TA = -40C to +125C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER RESET Output HIGH (Push-Pull Only) Open-Drain RESET Output Leakage Current (Note 1) SYMBOL VOH CONDITIONS VCC 1.8V, ISOURCE = 200A, reset not asserted MIN 0.8 VCC V TYP MAX UNITS
VCC 3.15V, ISOURCE = 500A, reset not asserted 0.8 VCC VCC 4.75V, ISOURCE = 800A, reset not asserted 0.8 VCC
ILKG
RESET not asserted VCC 1.0V, ISOURCE = 1A, reset asserted, TA = 0C to +85C 0.8 VCC 0.8 VCC 0.8 VCC 0.8 VCC
1.0
A
RESET Output HIGH (Push-Pull Only)
VOH
VCC 1.50V, ISOURCE = 100A, reset asserted VCC 2.55V, ISOURCE = 500A, reset asserted VCC 4.25V, ISOURCE = 800A, reset asserted VCC 1.8V, ISINK = 500A, reset asserted
V
0.3 0.3 0.3 0.3 VCC 0.7 VCC 1 100 200 25 50 1.6 75 2.4 2.60 0.3 VCC 0.7 VCC V
RESET Output LOW (Push-Pull Only) MANUAL RESET INPUT MR Input voltage MR Minimum Input Pulse MR Glitch Rejection MR to Reset Delay MR Pullup Resistance WATCHDOG INPUT Watchdog Timeout Period WDI Pulse Width (Note 2) WDI Input Voltage WDI Input Current
VOH
VCC 3.15V, ISINK = 1.2mA, reset asserted VCC 4.75V, ISINK = 3.2mA, reset asserted
VIL VIH
V s ns ns k
tWD tWDI VIL VIH IWDI
TA = -40C to +85C TA = -40C to +125C
1.12 0.80 50
s ns V A
WDI = VCC, time average WDI = 0, time average -20
120 -15
160
Note 1: Over-temperature limits are guaranteed by design and not production tested. Devices tested at +25C. Note 2: Guaranteed by design and not production tested.
4
_______________________________________________________________________________________
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX6826 toc01
RESET TIMEOUT PERIOD vs. TEMPERATURE
MAX6826 toc02
VCC TO RESET OUTPUT DELAY vs. TEMPERATURE
VCC FALLING, VCC = VTH - 100mV
MAX6826 toc03
13 12 11 SUPPLY CURRENT (A) 10 9 8 7 6 5 4 3 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) VCC = +3.3V, S VERSION VCC = +1.8V, V VERSION VCC = +5V, L VERSION
250 240 RESET TIMEOUT PERIOD (ms) 230 220 210 200 190 180 170 160 150 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
35 30 PROPAGATION DELAY (s) 25 20 15 10 5 0
-40 -20
0
20
40
60
80
100 120
TEMPERATURE (C)
WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE
MAX6826 toc04
NORMALIZED RESET THRESHOLD DELAY vs. TEMPERATURE
MAX6826 toc05
MAXIMUM VCC TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE
MAX6826 toc06
2.0 1.9 WATCHDOG TIMEOUT PERIOD (s) 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
1.06 1.04 RESET THRESHOLD (V) 1.02 1.00 0.98 0.96 0.94 -40 -20
120 100 80 60 40 20 0
TRANSIENT DURATION (s)
RESET OCCURS ABOVE CURVE
0
20
40
60
80
100 120
0
20 40 60 80 100 120 140 160 180 200 RESET THRESHOLD OVERDRIVE (mV), VTH - VCC
TEMPERATURE (C)
VRSTIN TO RESET OUTPUT DELAY vs. TEMPERATURE
MAX6826 toc07
MAXIMUM VRSTIN TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE
90 TRANSIENT DURATION (s) 80 70 60 50 40 30 20 10 RESET OCCURS ABOVE CURVE
MAX6826 toc08
25
VRSTIN FALLING VRSTIN = VRSTINTH - 30mV
100
PROPAGATION DELAY (s)
20
15
10
5
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
0 0 20 40 60 80 100 120 140 160 180 200 RESET THRESHOLD OVERDRIVE (mV), VRSTINTH - VRSTIN
_______________________________________________________________________________________
5
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.) VOLTAGE OUTPUT LOW vs. ISINK
MAX6826 toc09
VOLTAGE OUTPUT HIGH vs. ISOURCE
VCC = +2.9V 2.90 2.88 2.86 VOUT (V) 2.84 2.82 2.80
MAX6826 toc10
0.350 0.300 0.250 VOUT (V) 0.200 0.150 0.010 0.005 0 0
2.92
VCC = +2.9V
2.78 2.76 2.74 1 2 3 4 5 6 7 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 ISOURCE (mA) ISINK (mA)
Pin Description
PIN MAX 6826 MAX 6827 MAX 6828 MAX 6829 MAX 6830 MAX 6831 NAME FUNCTION
1
1
1
1
RESET
Active-Low Open-Drain or Push-Pull Reset Output. RESET changes from high to low when VCC1, VCC2, or RESET IN input drops below the selected reset threshold, MR is pulled low, or the watchdog triggers a reset. RESET remains low for the reset timeout period after all voltages exceed the device reset threshold, MR goes low to high, or the watchdog triggers a reset. Active-High Push-Pull Reset Output. RESET changes from low to high when VCC1, VCC2, or RESET IN input drops below the selected reset threshold, MR is pulled low, or the watchdog triggers a reset. RESET remains HIGH for the reset timeout period after all voltages exceed the device reset threshold, MR goes low to high, or the watchdog triggers a reset. Ground Manual Reset Input, Active-Low, Internal 50k 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. Watchdog Input. If WDI remains high or low for longer than the watchdog timeout period, the internal watchdog timer runs out and a reset is triggered for the reset timeout period. The internal watchdog timer clears whenever reset is asserted, the manual reset is asserted, or WDI sees a rising or falling edge. If WDI is left unconnected or is connected to a three-stated buffer output, the watchdog feature is disabled.
1
1
RESET
2 3
2 3
2 3
2 3
2 3
2 3
GND MR
4
4
4
4
4
4
WDI
6
_______________________________________________________________________________________
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
Pin Description (continued)
PIN MAX 6826 5 MAX 6827 5 MAX 6828 5 MAX 6829 MAX 6830 MAX 6831 NAME FUNCTION
RESET IN 5 5 6 5 6 VCC2 VCC
Input for User Adjustable RESET IN Monitor. High-impedance input for internal reset comparator. Connect this pin to an external resistor-divider network to set the reset threshold voltage. 0.63V (typ) threshold. Factory-Trimmed VCC2 Monitor. Connect this pin to a secondary powersupply voltage. Supply Voltage. Input for primary reset threshold monitor.
6
6
6
6
VCC
MAX6826/MAX6827/MAX6828
RESET TIMEOUT DELAY GENERATOR
RESET OR RESET
1.26V 0.63V
RESET IN
VCC
MR
WDI
WATCHDOG TRANSITION DETECTOR
WATCHDOG TIMER
Figure 1. Functional Diagram of RESET IN _______________________________________________________________________________________ 7
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
VCC
MAX6829/MAX6830/MAX6831
RESET TIMEOUT DELAY GENERATOR
RESET OR RESET
1.26V 0.63V
VCC2
VCC
MR
WDI
WATCHDOG TRANSITION DETECTOR
WATCHDOG TIMER
Figure 2. Functional Diagram of VCC2
Detailed Description
RESET/RESET Output
A microprocessor's (P's) reset input starts the P in a known state. The MAX6826-MAX6831 P supervisory circuits assert a reset to prevent code-execution errors during power-up, power-down, and brownout conditions. Whenever a monitored voltage falls below the reset threshold, the reset output asserts low for RESET and high for RESET. Once all monitored voltages exceed their reset thresholds, an internal timer keeps the reset output asserted for the specified reset timeout period (tRP); after this interval, reset output returns to its original state (Figure 3).
asserts a reset. Reset remains asserted while MR is low, and for the timeout period (140ms min) after it returns high. MR has an internal 50k pullup resistor, so it can be left open if not used. This input can be driven with CMOS logic levels or with open-drain/collector
VCC 1V VTH VTH 1V
RESET
tRP
tRD
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
8
RESET GND
tRP
tRD
Figure 3. Reset Timing Diagram
_______________________________________________________________________________________
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
VCC tRST RESET* tRP tWD tRP RESET GENERATOR WDI GND VCC VCC
MAX6828 MAX6831 RESET
RESET
P
GND
*RESET IS THE INVERSE OF RESET.
Figure 4. Watchdog Timing Relationship
Figure 6. Interfacing Open-Drain RESET to Ps with Bidirectional Reset I/O
VMONITOR R1
the maximum allowable leakage current is 10A and the maximum allowable load capacitance is 200pF.
MAX6826 MAX6827 MAX6828
RSTIN R2
Adjustable Reset Thresholds
The MAX6826/MAX6827/MAX6828 provide a user adjustable input to monitor a second voltage. The threshold voltage at RSTIN is typically 0.63V. To monitor a voltage higher than 0.63V, connect a resistordivider to the circuit as shown in Figure 5. The threshold at VMONITOR is: R1 + R2 VMONITOR _ TRIP = 0.63V R2 Note that RSTIN is powered by VCC, and its voltage must therefore remain lower than VCC.
VCC VRSTIN
Figure 5. Monitoring a Voltage
outputs. Connect a normally open momentary switch from MR to GND to create a manual-reset function; external debounce circuitry is not required. If MR is driven from long cables or the device is used in a noisy environment, connect a 0.1F capacitor from MR to GND to provide additional noise immunity.
Applications Information
Watchdog Input Current
The WDI inputs are internally driven through a buffer and series resistor from the watchdog timer (Figure 1). When WDI is left unconnected, the watchdog timer is serviced within the watchdog timeout period by a lowhigh-low pulse from the counter chain. For minimum watchdog input current (minimum overall power consumption), leave WDI low for the majority of the watchdog timeout period, pulsing it low-high-low once within the first 7/8 of the watchdog timeout period to reset the watchdog timer. If WDI is externally driven high for the majority of the timeout period, up to 160A can flow into WDI.
Watchdog Input
The watchdog circuit monitors the P's activity. If the P does not toggle (low to high or high to low) the watchdog input (WDI) within the watchdog timeout period (1.6s nominal), reset asserts for the reset timeout period. The internal 1.6s timer can be cleared by either a reset pulse or by toggling WDI. The WDI can detect pulses as short as 50ns. While reset is asserted, the timer remains cleared and does not count. As soon as reset is released, the timer starts counting (Figure 4). Disable the watchdog function by leaving WDI unconnected or by three-stating the driver connected to WDI. The watchdog input is internally driven low during the first 7/8 of the watchdog timeout period and high for the last 1/8 of the watchdog timeout period. When WDI is left unconnected, this internal driver clears the 1.6s timer every 1.4s. When WDI is three-stated or unconnected,
Interfacing to Ps with Bidirectional Reset Pins
Since the RESET output on the MAX6828/MAX6831 is open drain, these devices interface easily with Ps that have bidirectional reset pins, such as the Motorola 68HC11. Connecting the P supervisor's RESET output
9
_______________________________________________________________________________________
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
directly to the microcontroller's RESET pin with a single pullup resistor allows the device to assert a reset (Figure 6).
Watchdog Software Considerations
One way to help the watchdog timer monitor software execution more closely is to set and reset the watchdog input at different points in the program, rather than pulsing the watchdog input high-low-high or low-highlow. This technique avoids a stuck loop, in which the watchdog timer would continue to be reset inside the loop, keeping the watchdog from timing out. Figure 8 shows an example of a flow diagram where the I/O driving the watchdog input is set high at the beginning of the program, set low at the beginning of every subroutine or loop, then set high again when the program returns to the beginning. If the program should hang in any subroutine, the problem would quickly be corrected, since the I/O is continually set low and the watchdog timer is allowed to time out, causing a reset or interrupt to be issued. As described in the Watchdog Input Current section, this scheme results in higher time average WDI input current than does leaving WDI low for the majority of the timeout period and periodically pulsing it low-high-low.
Negative-Going VCC Transients These supervisors are relatively immune to short-duration, negative-going V CC transients (glitches), which usually do not require the entire system to shut down. Resets are issued to the P during power-up, powerdown, and brownout conditions. The Typical Operating Characteristics show a graph of the Maximum VCC Transient Duration vs. Reset Threshold Overdrive, for which reset pulses are not generated. The graph was produced using negative-going VCC pulses, starting at the standard monitored voltage and ending below the reset threshold by the magnitude indicated (reset threshold overdrive). The graph shows the maximum pulse width that a negative-going VCC transient can typically have without triggering a reset pulse. As the amplitude of the transient increases (i.e., goes farther below the reset threshold), the maximum allowable pulse width decreases. Typically, a VCC transient that goes 100mV below the reset threshold and lasts for 20s or less will not trigger a reset pulse. Ensuring a Valid RESET Output Down to VCC = 0
The MAX6826-MAX6831 are guaranteed to operate properly down to VCC = 1V. In applications that require valid reset levels down to VCC = 0, a pulldown resistor to active-low outputs (push/pull only, Figure 7) and a pullup resistor to active-high outputs (push/pull only) will ensure that the reset line is valid while the reset output can no longer sink or source current. This scheme does not work with the open-drain outputs of the MAX6828/MAX6831. The resistor value used is not critical, but it must be small enough not to load the reset output when VCC is above the reset threshold. For falling slew rates greater than 1V/s, a 100k is adequate.
START
SET WDI HIGH PROGRAM CODE
SUBROUTINE OR PROGRAM LOOP SET WDI LOW
VCC
RETURN
MAX6826 MAX6829
RESET R1 100k
Figure 8. Watchdog Flow Diagram
GND
Figure 7. RESET Valid to VCC = Ground Circuit 10 ______________________________________________________________________________________
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer
Threshold Suffix Guide
VCC THRESHOLD L M T S R Z Y W V RESET THRESHOLD (V) 4.63 4.38 3.08 2.93 2.63 2.32 2.19 1.67 1.58 VCC2 THRESHOLD Z Y W V I H G F E D RESET THRESHOLD (V) 2.313 2.188 1.665 1.575 1.388 1.313 1.110 1.050 0.833 0.788
MAX6826-MAX6831
Selector Guide
FUNCTION MAX6826 MAX6827 MAX6828 MAX6829 MAX6830 MAX6831 ACTIVE-LOW RESET -- -- -- -- ACTIVE-HIGH RESET -- -- -- -- OPEN-DRAIN RESET -- -- -- -- WATCHDOG INPUT MANUAL RESET INPUT FIXED VCC2 MONITOR -- -- -- ADJUSTABLE RESET INPUT -- -- --
Standard Versions Table* (continued)
MAX6829/MAX6830/MAX6831 VCC 3.3V TZ SV SH SF SD 2.5V -- ZW YH YG YD 1.8V -- -- WI VF VD VCC2 -- 2.5V 1.8V 1.5V 1.2V 0.9V
Chip Information
TRANSISTOR COUNT: 750 PROCESS TECHNOLOGY: BiCMOS
Typical Operating Circuit
VCC VCC2 VCC VCC2 RESET RESET CORE SUPPLY I/O SUPPLY
*Samples are typically available for standard versions only. For the MAX6829/MAX6830/MAX6831, standard versions require a 2.5k minimum order increment, while nonstandard versions require a 10k minimum order increment and are not typically available in samples. Contact factory for availability.
MAX6829 MAX6830 MAX6831 WDI
MANUAL RESET MR GND
P
I/O
______________________________________________________________________________________
11
Dual Ultra-Low-Voltage SOT23 P Supervisors with Manual Reset and Watchdog Timer MAX6826-MAX6831
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.)
6LSOT.EPS
PACKAGE OUTLINE, SOT 6L BODY
21-0058
G
1 1
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 Printed USA is a registered trademark of Maxim Integrated Products, Inc.
(c) 2005 Maxim Integrated Products

▲Up To Search▲

Price & Availability of MAX6830UT-T

	To Download MAX6830UT-T Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .