MAX6807US26-T中文资料

General Description

The MAX6806/MAX6807/MAX6808 precision voltage detectors are ideal for accurate monitoring of power supplies in digital systems. They provide circuit reliabili-ty and reduce total cost by eliminating external compo-nents and adjustments.

The MAX6806/MAX6807/MAX6808 assert a reset signal whenever the supply voltage (V CC ) falls below the factory-preset, ±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 fea-tures an active-low, push-pull RESET output; the MAX6807features an active-high, push-pull RESET output; and the MAX6808 features an active-low, open-drain RESET out-put. RESET is valid for V CC down to 1V (MAX6806/MAX6808), and RESET (MAX6807) is guaranteed for V CC down to 1.2V.

The MAX6806/MAX6807/MAX6808 are available in 3-pin SC70, 3-pin SOT23, 8-pin μMAX, 8-pin SO, and 4-pin SOT143 packages. The SOT143 package includes a manual-reset input.

Applications

Computers Automotive

Controllers

Bar-Code Scanners

Intelligent Instruments

Critical μP and μC Power Monitoring Portable/Battery-Powered Equipment

Features

o Preset Reset Thresholds: 4.6V and 2.6V (2.3V also available for MAX6806 only)o ±2% Accurate Reset Thresholds

o Reset Output Available in Active-Low (MAX6806),Active-High (MAX6807), and Open-Drain (MAX6808) Versions o Immune to Power-Supply Transients

o RESET Valid to V CC = 1.0V (MAX6806/MAX6808)o 35μA Supply Current o No External Components

o Manual Reset Available with 4-Pin SOT143Package o Miniature 3-Pin SC70, 3-Pin SOT23, and 4-Pin SOT143 Packages o 8 Lead μMAX and 8 Lead SO Packages are Pin Compatible with the MC33064/MC33164/MC34064/MC34164

Voltage Detectors

________________________________________________________________Maxim Integrated Products

1

19-1421; Rev 2; 4/01

Ordering Information

Selector Guide and Pin Configurations appear at end of data sheet.

* SOT23, SOT143, and SC70s are 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 for SOT23

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at https://www.wendangku.net/doc/2d13407003.html,.

Typical Operating Circuit

M A X 6806/M A X 6807/M A X 6808

Voltage Detectors 2_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V CC = +5V, T A = -40°C to +85°C, unless otherwise noted. Typical values are at T A = +25°C.) (Note 1)

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.

Note1:All devices are 100% production tested at T A = +25°C, and are guaranteed by design for T A = T MIN to T MAX , as specified.Note 2:RESET output for MAX6806/MAX6808, RESET output for MAX6807.

V CC to GND ..........................................................-0.3V to +6.0V RESET, RESET to GND

(MAX6806/MAX6807) ................................-0.3V to (V CC + 0.3V)RESET to GND (MAX6808)...................................-0.3V to + 6.0V MR to GND (SOT143 package only)....................-0.3V to + 6.0V Input Current, V CC ...........................................................±20mA Output Current, RESET, RESET .......................................±20mA Rate of Rise, V CC ...........................................................100V/μs

Continuous Power Dissipation (T A = +70°C)

SOT23, SOT143 (derate 4mW/°C above +70°C) .........320mW SC70 (derate 2.17mW/°C above +70°C) .....................174mW μMAX (derate 4.5mW/°C above +70°C) ......................362mW SO (derate 5.9mW/°C above +70°C) ...........................471mW Operating Temperature Range ..........................-40°C to +85°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10s).................................+300°C

MAX6806/MAX6807/MAX6808

Voltage Detectors

Typical Operating Characteristics

(T A = +25°C, unless otherwise noted.)

1052015302535454050-60

-30

30

60

120

90

SUPPLY CURRENT vs. TEMPERATURE

TEMPERATURE (°C)

S U P P L Y C U R R E N T (μA )

25

29273331353743413945

-60-30-150-45153045756090105120135

POWER-DOWN RESET DELAY

vs. TEMPERATURE

TEMPERATURE (°C)

R E S E T D E L A Y (μs )

465798111012-60

-30

30

60

120

90

POWER-UP RESET DELAY vs. TEMPERATURE

TEMPERATURE (°C)D E L A Y T I M E (μs )

0.9900

0.99400.99200.99800.99601.00201.00001.00401.00801.00601.0100

-40-15

-3015

30

60

45

85

75

NORMALIZED RESET THRESHOLD

vs. TEMPERATURE

TEMPERATURE (°C)N O R M A L I Z E D R E S E T T H R E S H O L D

Pin Description

M A X 6806/M A X 6807/M A X 6808

Voltage Detectors 4

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_______________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 micro-processor (μP) supervisory circuits that offer a reset timeout period, the MAX6806 and MAX6807 RESET goes high and RESET goes low virtually immediately once V CC exceeds the reset threshold. I f a brownout occurs (V CC falls below the reset threshold), RESET goes low and RESET goes high. RESET is guaranteed to be a logic low for V CC ≥1V and RESET is guaran-teed to be a logic high for V CC ≥1.2V.

The MAX6808 features an active-low, open-drain RESET output. The output sinks current when V CC 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 100k ?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 sec-tion).

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 80k ?pull-down resistor, so the input may be left unconnected if not used. Connect a normally open momentary switch from MR to V CC to create a manual-reset 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 hys-teresis 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 oscil-lating (chattering) when V CC is near the reset threshold.

Reset Threshold Accuracy

The MAX6806/MAX6807/MAX6808 are ideal for sys-tems using a 5V ±5%, 3V ±5%, or 2.5V ±5% power supply with I Cs 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 oper-ating voltage range for the system ICs.

Figure 1. The MAX6808 open-drain RESET output allows use with multiple supplies.

Figure 2. Input and Output Waveforms with V CC Varied

Applications Information

Negative-Going V CC 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, neg-ative-going V CC transients.

Figure 3 displays typical transient durations vs. reset-comparator overdrive for which the MAX6806/MAX6807/MAX6808 do not generate a reset pulse. The graph was generated using a negative-going pulse applied to V CC ,starting 0.5V above the actual reset threshold and end-ing below it by the magnitude indicated (reset-compara-tor overdrive). The graph indicates the maximum pulse width a negative-going V CC 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 V CC pro-vides additional transient immunity.

Ensuring a Valid Reset Output Down to

V CC = Ground

When V CC falls below 1V, the MAX6806/MAX6808RESET 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 applica-tions, since most circuitry is inoperative when V CC is below 1V. I n 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, 100k ?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.

MAX6806/MAX6807/MAX6808

Voltage Detectors

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Figure 3. Maximum Transient Duration without Causing a Reset Pulse vs. Reset Comparator Overdrive

Figure 4. RESET / RESET Valid to V CC = Ground Circuit

M A X 6806/M A X 6807/M A X 6808

Interfacing to μPs with Bidirectional Reset Pins

μPs with bidirectional reset pins (such as the Motorola 68HC11 series) can contend with push-pull RESET out-puts, resulting in indeterminate logic levels. Use the MAX6808 with the open-drain RESET when interfacing to this type of controller.

Voltage Detectors 6_______________________________________________________________________________________

Figure 5. Interfacing to μPs with Bidirectional Reset I/O

Selector Guide

Other voltage thresholds may be available. Contact factory for availability.Selector Guide (continued)

MAX6806/MAX6807/MAX6808Voltage Detectors _______________________________________________________________________________________7

M A X 6806/M A X 6807/M A X 6808

Voltage Detectors 8_______________________________________________________________________________________

___________________Chip Information

TRANSISTOR COUNT: 72

Pin Configurations

Package Information

MAX6806/MAX6807/MAX6808Voltage Detectors

M A X 6806/M A X 6807/M A X 6808

Voltage Detectors 10______________________________________________________________________________________

Package Information (continued)

Package Information (continued)

MAX6806/MAX6807/MAX6808Voltage Detectors Array

______________________________________________________________________________________11

M A X 6806/M A X 6807/M A X 6808

Voltage Detectors 12______________________________________________________________________________________

Package Information (continued)

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_____________________13?2001 Maxim Integrated Products

Printed USA

is a registered trademark of Maxim Integrated Products.

Package Information (continued)

MAX6806/MAX6807/MAX6808

Voltage Detectors