Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset PDIP 8

_______________General Description

The MAX814/MAX815/MAX816 are high-accuracy

microprocessor (µP) supervisory circuits that provide

power-on reset, watchdog, and power-fail functions.

They eliminate manual trimming and improve reliability

in critical applications needing high-accuracy reset

thresholds. The RESET output is guaranteed to be in

the correct state for V

down to 1V. The reset com-

parator is designed to ignore fast transients on V

Reset thresholds are available for operation with a vari-

ety of 3V and 5V supply voltages.

A 75µA maximum supply current makes the MAX814/

MAX815/MAX816 ideal for use in portable equipment. All

three devices are available in 8-pin DIP and SO pack-

ages. See the Selector Table for a review of features.

________________________Applications

Medical Equipment

Controllers

Intelligent Instruments

Critical µP Power Monitoring

Portable/Battery-Powered Equipment

Set-Top Boxes

____________________________Features

♦ ±1% Worst-Case Reset Threshold Accuracy

♦ 4.8V, 4.7V, 4.55V, 3.03V, or Adjustable Reset

Thresholds

♦ ±1% Low-Line Threshold Accuracy (MAX814)

60mV Above Reset Threshold

♦ 200ms Reset Time Delay

♦ Active-Low RESET

Output

Active-High RESET Output (MAX814/MAX816)

♦ 75µA Max Supply Current

♦ Guaranteed RESET

Valid to V

= 1V

♦ Manual Reset Input

♦ ±2% Power-Fail Comparator

♦ Independent Watchdog with 1.56sec Timeout

(MAX815)

♦ Power-Supply Glitch Immunity

♦ 8-Pin SO and DIP Packages

MAX814/MAX815/MAX816

±1% Accuracy, Low-Power, +3V and +5V

µP Supervisory Circuits

________________________________________________________________ Maxim Integrated Products 1

LOW LINE

GND

PFO

PFI

RESET

MAX814

DIP/SO

TOP VIEW

WDI

GND

PFO

PFI

WDO

RESET

MAX815

DIP/SO

RESET IN

GND

PFO

PFI

RESET

MAX816

DIP/SO

__________________________________________________________Pin Configurations

19-0412; Rev 1; 12/05

_____________________Selector Table

Reset Trip Thresholds table appears at end of data sheet.

Ordering Information continued at end of data sheet.

FEATURE MAX814 MAX815 MAX816

RESET Output

✔ ✔ ✔

RESET Output

✔ ✔

Manual Reset

✔ ✔ ✔

Reset Voltage K, L, N, T K, L, N, T Adjustable

Power-Fail Monitor

✔ ✔ ✔

Low-Line Detector

✔

Watchdog Circuit

✔

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.

PART* TEMP RANGE PIN-PACKAGE

MAX814_CPA

0°C to +70°C 8 PDIP

______________Ordering Information

*The MAX814/MAX815 offer a choice of reset threshold voltages.

From the Reset Trip Threshold table, select the suffix corre-

sponding to the desired threshold and insert it into the blank to

complete the part number.

Devices are available in both leaded and lead-free packaging.

Specify lead free by adding the + symbol at the end of the part

number when ordering.

Summary of content (16 pages)

PAGE 1
9-0412; Rev 1; 12/05 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits ____________________________Features The MAX814/MAX815/MAX816 are high-accuracy microprocessor (µP) supervisory circuits that provide power-on reset, watchdog, and power-fail functions. They eliminate manual trimming and improve reliability in critical applications needing high-accuracy reset thresholds. The RESET output is guaranteed to be in the correct state for VCC down to 1V.
PAGE 2
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect GND) VCC ....................................................................-0.3V to +6.0V All Other Pins (Note 1)........................... -0.3V to (VCC + 0.3V) Terminal Current (PFI, RESET IN, MR)................................10mA Terminal Current (all other pins) .........................................
PAGE 3
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits MAX814/MAX815/MAX816 ELECTRICAL CHARACTERISTICS, +5V Parts (MAX814/MAX815K, L, N) (continued) (VCC = 4.85V to 5.5V for MAX814K/MAX815K, VCC = 4.75V to 5.5V for MAX814L/MAX815L, VCC = 4.60V to 5.5V for MAX814N/ MAX815N, TA = TMIN to TMAX, unless otherwise noted.
PAGE 4
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits ELECTRICAL CHARACTERISTICS, +3V Parts (MAX814/MAX815T, MAX816) (continued) (VCC = 3.06V to 5.5V for MAX814T/MAX815T and MAX816, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER WDI Pulse Width SYMBOL tWP CONDITIONS MAX815T VRT(max) < VCC < 3.6V; MAX815T WDI Input Threshold VWDI VCC = 5.0V; MAX815T 100 4.5V < VCC < 5.
PAGE 5
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits VCC = 3.3V 50 45 VCC = 2.5V 40 35 MAX814-02 60 VCC = 5.0V 55 50 45 VCC = 3.3V 40 195 VCC = 3.3V 190 185 VCC = 5.0V 180 30 0 20 40 60 80 100 175 -60 -40 -20 TEMPERATURE (°C) 20 40 60 80 100 -60 1.715 1.710 20 15 20 40 60 1.700 1.695 1.690 1.685 2.520 2.510 2.500 2.490 2.480 1.680 2.470 1.675 2.460 80 100 80 100 2.530 2.450 1.670 0 60 2.550 PFI THRESHOLD (V) PFI THRESHOLD (V) 25 40 2.540 1.
PAGE 6
____________________________Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) RESET THRESHOLD DEVIATION vs. TEMPERATURE 5V PARTS (MAX814/MAX815K, L, N) RESET THRESHOLD DEVIATION vs. TEMPERATURE 3V PARTS (MAX814T/MAX815T, MAX816) RESET THRESHOLD DEVIATION (mV) 1 0 -1 -2 MAX814-08 1 MAX814-07 RESET THRESHOLD DEVIATION (mV) 2 0 -1 -2 -3 -60 -40 -20 0 20 40 60 -60 80 100 -40 -20 40 20 60 80 100 MAXIMUM TRANSIENT DURATION vs.
PAGE 7
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits PIN MAX814 MAX815 MAX816 1 1 1 2 2 — NAME FUNCTION MR Manual-Reset Input. Triggers a reset when pulled below 1.10V. This activelow input has an internal 150µA pullup current to VCC, and can be driven with CMOS logic or shorted to GND with a switch or transistor. VCC Positive Power-Supply Input. When VCC is below the reset threshold voltage*, RESET is low, and remains low for a minimum of 140ms after it rises above the threshold.
PAGE 8
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits VCC +3.3V +5V +12V SUPPLY VCC VCC µP MAX814 MAX814K/L/N RESET RESET PFI PFI RESET MR RESET NMI LOW LINE MANUAL RESET INPUT INTERRUPT PFO MR RESET PFO GND GND Figure 1a. Typical Application for Dual +3.3V and +5V Systems Figure 1b.
PAGE 9
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits 8 RESET 150µA 1 MR RESET GENERATOR 7 MAX814/MAX815/MAX816 MAX814 MAX815 6 WDI WATCHDOG TRANSITION DETECTOR WATCHDOG TIMER 8 WDO RESET TIMEBASE 2 VCC 1 MR 150µA 7 RESET GENERATOR RESET 60mV 2 VCC 6 LOW LINE RESET THRESHOLD 4 PFI RESET THRESHOLD 4 PFI 5 5 PFO POWER- FAIL THRESHOLD PFO POWER-FAIL THRESHOLD 3 GND 3 GND Figure 4. MAX814 Block Diagram Figure 5.
PAGE 10
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits Reset Threshold The MAX814/MAX815 have fixed, factory-set reset thresholds, signified by the first suffix letter in the part number (see Figure 7 for more information on reset ranges). The MAX816 has an adjustable reset threshold. MAX814/MAX815 K-suffix parts have a minimum reset threshold set to 4.75V, worst case. They are intended for 5.
PAGE 11
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits VRT = ( ) VRIT × R1 + R2 R2 where VRT = the desired reset threshold, VRIT is the RESET IN threshold (1.700V), R1 is the resistor connected between V RT and RESET IN, and R2 is the resistor connected between RESET IN and GND. Resistors R1 and R2 can have very high values.
PAGE 12
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits tWP tWD tWD tWDO tWD VCC ∆VLL 60mV VRT VLLT VRT VCC WDI 0V tRS tRS MR RESET VCC WDO 0V RESET RESET VCC VCC 0V MR VCC 0 tMD 0V tMR VCC WDO (MAX815) 0 Figure 8. MAX815 Watchdog Timing VCC LOW LINE (MAX814) 0 where CHOLD is the capacitance (in Farads), ILOAD is the current being drained from the capacitor (in Amperes), and VLR is the low-line to reset threshold difference (in Volts). Figure 9.
PAGE 13
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits +5V VCC 340kΩ 1% MAX814 MAX815 MAX816 MAX814K/L/N MR MAX815K/L/N 100kΩ 1% RESET TO µP RESET PFI PFO GND R1 PARAMETER MIN TYP MAX +12V Reset 10.57 11.00 11.45 Threshold at +25°C UNIT V Figure 10. RESET Valid to Ground Circuit Figure 11. Monitoring Both +5V and +12V Monitoring Voltages Other than VCC Monitor voltages other than the VCC by connecting a voltage divider to PFI and adjusting the ratio appropriately.
PAGE 14
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits +5V BUFFERED RESET TO OTHER SYSTEM COMPONENTS VCC 100kΩ MR R1 MAX814 MAX815 PFO PFI MAX816 R2 VCC 100kΩ 2N3904 TO µP RESET GND VCC MAX814 MAX815 MAX816 µP 4.7kΩ RESET RESET GND V- GND +5V MR 0V +5V PFO Figure 14. Interfacing to µPs with Bidirectional Reset I/O 0V V- VTRIP 0V 5 - 2.5 2.5 - VTRIP , VTRIP < 0V = R1 R2 VPFT = 2.5V (K, L, N); 1.70V (T AND MAX816) Figure 12.
PAGE 15
±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits PART* TEMP.
PAGE 16
MAX814/MAX815/MAX816 ±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuits 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.) D E DIM E1 A A1 A2 A3 B B1 C D1 E E1 e eA eB L A3 A A2 L A1 0° - 15° C e B1 eA B eB D1 Plastic DIP PLASTIC DUAL-IN-LINE PACKAGE (0.300 in.) INCHES MAX MIN 0.200 – – 0.015 0.175 0.125 0.080 0.055 0.022 0.016 0.065 0.045 0.