MAXIM MAX6807US23-T

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
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For small orders, phone 1-800-835-8769.
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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
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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.
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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
Figure 2. Input and Output Waveforms with VCC Varied
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VOL
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
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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
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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
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7
MAX6806/MAX6807/MAX6808
Pin Configurations
Voltage Detectors
SC70, 3L.EPS
MAX6806/MAX6807/MAX6808
Package Information
8
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Voltage Detectors
SOTPO3L.EPS
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MAX6806/MAX6807/MAX6808
Package Information (continued)
Voltage Detectors
SOT1434.EPS
MAX6806/MAX6807/MAX6808
Package Information (continued)
10
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Voltage Detectors
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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
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is a registered trademark of Maxim Integrated Products.