Datasheet

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

General Description

The MAX706P/R/S/T, MAX706AP/AR/AS/AT, and

MAX708R/S/T microprocessor (µP) supervisory circuits

reduce the complexity and number of components

required to monitor +3V power-supply levels in +3V to

+5V µP systems. These devices significantly improve

system reliability and accuracy compared to separate

ICs or discrete components.

The MAX706P/R/S/T and MAX706AP/AR/AS/AT supervi-

sory circuits provide the following four functions:

1) A reset output during power-up, power-down, and

brownout conditions.

2) An independent watchdog output that goes low if the

watchdog input has not been toggled within 1.6s.

3) A 1.25V threshold detector for power-fail warning,

low-battery detection, or for monitoring a power

supply other than the main supply.

4) An active-low, manual-reset input.

The only difference between the MAX706R/AR,

MAX706S/AS, and MAX706T/AT is the reset-threshold

voltage levels, which are 2.63V, 2.93V, and 3.08V,

respectively. All have active-low reset output signals.

The MAX706P/AP are identical to the MAX706R/AR,

except the reset output signal is active-high. The watch-

dog timer function for the MAX706AP/AR/AS/AT dis-

ables when the WDI input is left open or connected to a

high-impedance state of a low-leakage tri-state output.

The MAX708R/S/T provide the same functions as the

MAX706R/S/T and MAX706AR/AS/AT except they do

not have a watchdog timer. Instead, they provide both

RESET and RESET outputs. As with the MAX706,

devices with R, S, and T suffixes have reset thresholds

of 2.63V, 2.93V, and 3.08V, respectively.

These devices are available in 8-pin SO, DIP, and

µMAX

packages and are fully specified over the oper-

ating temperature range.

Applications

Battery-Powered Equipment

Portable Instruments

Computers

Controllers

Intelligent Instruments

Critical µP Power Monitoring

Features

o µMAX Package, Small 8-Pin SO

o Precision Supply-Voltage Monitors

2.63V (MAX706P/R, MAX706AP/AR, and MAX708R)

2.93V (MAX706S, MAX706AS, and MAX708S)

3.08V (MAX706T, MAX706AT, and MAX708T)

o 200ms Reset Time Delay

o Debounced TTL/CMOS-Compatible Manual Reset

Input

o 100µA Quiescent Current

o WDI Disable Feature (MAX706AP/AR/AS/AT)

o Watchdog Timer: 1.6s Timeout

o Reset Output Signal:

Active-High Only (MAX706P, MAX706AP)

Active-Low Only (MAX706R/S/T, MAX706AR/AS/AT)

Active-High and Active-Low (MAX708R/S/T)

o Voltage Monitor for Power-Fail or Low-Battery

Warning

o 8-Pin Surface-Mount Package

o Guaranteed RESET Assertion to V

= 1V

MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T

+3V Voltage Monitoring, Low-Cost µP

Supervisory Circuits

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-0099; Rev 5; 4/06

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.

Ordering Information continued at end of data sheet.

Pin Configurations appear at end of data sheet.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

PART†

TEMP

RANGE

PIN-

PACKAGE

PKG

CODE

MAX706PCPA 0°C to +70°C 8 PDIP P8-1

MAX706PCSA 0°C to +70°C 8 SO S8-2

MAX706PCUA 0°C to +70°C 8 µMAX U8-1

MAX706PEPA -40°C to +85°C 8 PDIP P8-1

†

SO, µMAX, and PDIP packages are available in lead-free.

PFI

GND

PFO

WDO

RESET

UNREGULATED

PUSHBUTTON

SWITCH

WDI

I/O LINE

INTERRUPT

µP

MAX639

DC-DC

CONVERTER

+3V/+3.3V

MAX706R/S/T

MAX706AR/AS/AT

RESET

NMI

Typical Operating Circuits

Typical Operating Circuits continued at end of data sheet.

Summary of content (15 pages)

PAGE 1
9-0099; Rev 5; 4/06 +3V Voltage Monitoring, Low-Cost µP Supervisory Circuits Features The MAX706P/R/S/T, MAX706AP/AR/AS/AT, and MAX708R/S/T microprocessor (µP) supervisory circuits reduce the complexity and number of components required to monitor +3V power-supply levels in +3V to +5V µP systems. These devices significantly improve system reliability and accuracy compared to separate ICs or discrete components.
PAGE 2
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T +3V Voltage Monitoring, Low-Cost µP Supervisory Circuits ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VCC ........................................................................-0.3V to +6V All Other Inputs (Note 1)..........................-0.3V to (VCC + 0.3V) Input Current VCC ..................................................................................20mA GND .........................................................................
PAGE 3
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits (MAX70_P/R, MAX706AP/AR: VCC = 2.7V to 5.5V; MAX70_S, MAX706AS: VCC = 3.0V to 5.5V; MAX70_T, MAX706AT: VCC = 3.15V to 5.5V; TJ = TA = TMIN to TMAX, unless otherwise noted. Typical values are at TJ = TA = +25°C.) (Note 2) PARAMETER Output-Voltage High (MAX706P) (MAX706AP) Output-Voltage High (MAX708_) SYMBOL CONDITIONS MIN VOH VRST(MAX) < VCC < 3.6V ISOURCE = 215µA VCC – 0.6 VOL VRST(MAX) < VCC < 3.6V ISINK = 1.2mA VOH 4.5 < VCC < 5.
PAGE 4
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T +3V Voltage Monitoring, Low-Cost µP Supervisory Circuits ELECTRICAL CHARACTERISTICS (continued) (MAX70_P/R, MAX706AP/AR: VCC = 2.7V to 5.5V; MAX70_S, MAX706AS: VCC = 3.0V to 5.5V; MAX70_T, MAX706AT: VCC = 3.15V to 5.5V; TJ = TA = TMIN to TMAX, unless otherwise noted. Typical values are at TJ = TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN VOH VRST(MAX) < VCC < 3.6V ISOURCE = 500µA 0.8 x VCC VOL VRST(MAX) < VCC < 3.
PAGE 5
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits _______________________________________________________________________________________ 5 MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T Typical Operating Characteristics (TA = +25°C, unless otherwise noted.
PAGE 6
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T Pin Description MAX706P MAX706AP SO/DIP µMAX SO/DIP µMAX MAX708R/S/T MR 4 VCC Supply Voltage Input 5 GND Ground 1 3 1 3 2 4 2 4 2 3 5 3 5 3 5 7 4 5 6 7 FUNCTION Active-Low, Manual-Reset Input. Pull MR below 0.6V to trigger a reset pulse. MR is TTL/CMOS compatible when VCC = 5V and can be shorted to GND with a switch. MR is internally connected to a 70µA source current.
PAGE 7
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits 6 WATCHDOG TRANSITION DETECTOR VCC 70µA MR VCC PFI WATCHDOG TIMER 8 WDO VCC MR 1 2 4 RESET 70µA TIMEBASE FOR RESET AND WATCHDOG RESET GENERATOR 8 7 VCC RESET GENERATOR 2 7 RESET RESET (RESET) 2.63V MAX706P/R 2.93V MAX706S MAX706P/R/S/T 3.08V MAX706T MAX706AP/AR/AS/AT PFI 5 1 PFO 4 2.63V MAX708R 2.93V MAX708S 3.08V MAX708T MAX708R/S/T 5 PFO 1.25V 1.25V 3 GND ( ) ARE FOR MAX706P/AP. 3 GND Figure 1.
PAGE 8
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T +3V Voltage Monitoring, Low-Cost µP Supervisory Circuits +3.3V VCC +1V VRST VRST tRST tRST +12V +3V/+3.3V RESET 0V +3.3V TO µP MAX706_ MAX708R/S/T RESET 0V MR 130kΩ 1% +3.3V MR* 0V PFI PFO GND tMD tMR +3.3V WDO* RESET (RESET) VCC 1MΩ 1% *NOTE: MR EXTERNALLY DRIVEN LOW. WDO TIMING SHOWN FOR MAX706P/R/S/T. 0V Figure 3. RESET, RESET, MR, and WDO Timing tWP tWD tWD PARAMETER MIN TYP MAX UNIT +12V RESET 10.24 THRESHOLD AT +25°C 10.
PAGE 9
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits VIN MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T To build an early-warning power-failure circuit, use the power-fail comparator input (PFI) to monitor the unregulated DC supply voltage (see the Typical Operating Circuits). Connect the PFI to a resistive-divider network such that the voltage at PFI falls below 1.25V just before the regulator drops out. Use PFO to interrupt the µP so it can prepare for an orderly power-down.
PAGE 10
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T +3V Voltage Monitoring, Low-Cost µP Supervisory Circuits sees 1.25V when V IN falls to the desired trip point (VTRIP). Resistor R3 adds hysteresis. R3 will typically be an order of magnitude greater than R1 and R2. The current through R1 and R2 should be at least 1µA to ensure that the 25nA (max) PFI input current does not shift the trip point significantly. R3 should be larger than 10kΩ to prevent it from loading down the PFO pin.
PAGE 11
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits Typical Operating Circuits (continued) TOP VIEW MR 1 VCC 2 GND 3 MAX706P MAX706AP PFI 4 8 WDO 7 RESET 6 WDI 5 PFO UNREGULATED DC MAX639 DC-DC CONVERTER -3V/+3.3V µP VCC VCC DIP/SO RESET PFI MR 1 8 WDO VCC 2 7 RESET MAX706R/S/T GND 3 MAX706AR/AS/AT 6 WDI PFI 4 5 PFO 8 RESET 7 RESET 6 N.C.
PAGE 12
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.) CDIPS.
PAGE 13
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits α α ______________________________________________________________________________________ 13 MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T Package Information (continued) (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.
PAGE 14
MAX706P/R/S/T, MAX706AP/AR/AS/AT, MAX708R/S/T +3V Voltage Monitoring, Low-Cost µP Supervisory Circuits Package Information (continued) (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.
PAGE 15
+3V Voltage Monitoring, Low-Cost µP Supervisory Circuits PDIPN.EPS 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.