Rainbow Electronics MAX6869 User Manual

General Description

The MAX6854–MAX6869 ultra-low-current (170nA, typ) microprocessor (µP) supervisory circuits combine voltage monitoring, watchdog timer, and manual reset input functions in a 5-pin SOT23 package. These devices assert a reset signal whenever the monitored voltage drops below the factory-trimmed reset threshold voltage, manual reset is asserted, or the watchdog timer expires. The reset output remains asserted for a minimum timeout period after VCCrises above the reset threshold and manual reset is deasserted. Factory-trimmed reset threshold voltages are offered from +1.575V to +4.625V in approximately 100mV increments (see Threshold Suffix Guide). Each device is offered with six minimum reset timeout options, ranging from 10ms to 1200ms.

The MAX6854–MAX6869 are offered in a variety of configurations (see Selector Guide). The MAX6854– MAX6856 and MAX6861–MAX6869 provide a manual reset input, MR. The MAX6864–MAX6869 offer a watchdog timer that monitors activity at the WDI input for code execution errors. The MAX6864–MAX6869 offer watchdog timeout options of 3.3s or 209s (typ). The MAX6861–MAX6863 feature a pin-selectable reset delay period of 10ms or 150ms (min). Push-pull active-low, push-pull active-high, and open-drain active-low reset outputs are available.

Applications

Portable/Battery-Powered Equipment PDAs/Cell Phones MP3 Players/Pagers Glucose Monitors/Patient Monitors

Features

♦ Ultra-Low 170nA (typ) Supply Current ♦ Reset Thresholds from +1.575V to +4.625V in

Approximately 100mV Increments

♦ 6 Minimum Reset Timeout Period Options from

10ms to 1200ms

♦ Manual Reset Option ♦ Watchdog Timer Option ♦ Pin-Selectable 10ms/150ms (min) Reset Timeout

Period (MAX6861/MAX6862/MAX6863)

♦ Immune to Short VCCTransients ♦ Guaranteed Reset Valid to VCC= +1.1V ♦ Three Reset Output Options:

Push-Pull RESET

Push-Pull RESET Open-Drain RESET

♦ No External Components ♦ Small 5-Pin SOT23 Package ♦ Pin Compatible to the TPS3836–TPS3838

(MAX6861/MAX6862/MAX6863)

MAX6854–MAX6869

Nanopower µP Supervisory Circuits with

Optional Manual Reset, Watchdog Timer

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

PART

†

PIN-PACKAGE

MAX6854UK_ _D_-T*

5 SOT23-5

MAX6855UK_ _D_-T*

5 SOT23-5

19-3139; Rev 0; 2/04

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 on last page.

†

Insert reset threshold suffix (see Table 2, Threshold Suffix Guide) after UK. Insert the number corresponding to the desired reset timeout period (see Table 4, Reset Timeout Period) after “D.”

Note: Sample stock is generally held on standard versions only (see Table 5, Standard Versions Table). Standard versions have an order increment of 2500 pieces. Nonstandard versions have an order increment of 10,000 pieces. Contact factory for availability of nonstandard versions.

*Future product—Contact factory for availability.

Pin Configurations appear at the end of data sheet. Selector Guide appears at the end of data sheet.

Typical Operating Circuit

MAX6864 MAX6867

µP

GND

MANUAL

RESET

I/O

0.1µF

RESET

WDI

TEMP RANGE

-40°C to +85°C

MAX6854–MAX6869

Nanopower µP Supervisory Circuits with Optional Manual Reset, Watchdog Timer

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= 1.2V to 5.5V, TA= -40°C to +85°C, unless otherwise specified. Typical values are at VCC= 2.5V, TA= +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.

VCC, Open-Drain RESET to GND..........................-0.3V to +6.0V

MR, Push-Pull RESET, RESET,

WDI, CT, I.C............................................-0.3V to (V

+ 0.3V)

Input Current, Output Current (all pins)............................±20mA

Continuous Power Dissipation (T

= +70°C)

5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature .....................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER

SYMBOL

CONDITIONS MIN

TYP

MAX

UNITS

TA ≥ 0°C 1.1 5.5

Supply Voltage V

TA = -40°C to +85°C 1.2 5.5

VCC = 5.0V 210 400 nA VCC = 3.3V 190 380 nA

VCC > VTH, no load, reset output

VCC = 1.8V 170 370 nA

Supply Current I

715µA

VCC Reset Threshold V

falling (see Table 2)

VTH +

Reset Threshold Hysteresis V

HYST

Reset asserted to reset deasserted 0.5

D1 10 15 25 D2 40 60 80 D3 150 225 300 D4 D5 300 450 600

Reset Timeout Period t

VCC = VTH + 150mV (Figures 2 and 3)

D6 600 900

VCC to Reset Delay t

VCC falling from (VTH + 100mV) to (V

- 100mV) at 10mV/µs

40 µs

VCC ≥ 1.1V, I

SINK

= 50µA,

RESET asserted, T

≥ 0°C

0.3

≥ 1.2V, I

SINK

= 100µA,

RESET asserted

0.3

≥ 2.12V, I

SINK

= 1.2mA,

RESET asserted

0.3

≥ 1.71V, I

SOURCE

= 200µA,

RESET deasserted, push-pull RESET only

0.8 x V

RESET Output Voltage

≥ 2.38V, I

SOURCE

= 500µA,

RESET deasserted, push-pull RESET only

0.8 x V

Open-Drain RESET Leakage Current

LKG

RESET deasserted 25 nA

deasserted (Note 2) VCC < VTH, no load, reset output asserted

2.5%

1200 1800 2400

2.5%

1200

MAX6854–MAX6869

Nanopower µP Supervisory Circuits with

Optional Manual Reset, Watchdog Timer

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= 1.2V to 5.5V, TA= -40°C to +85°C, unless otherwise specified. Typical values are at VCC= 2.5V, TA= +25°C.) (Note 1)

PARAMETER

CONDITIONS MIN

UNITS

≥ 1.1V, I

SOURCE

= 10µA,

RESET asserted, T

≥ 0°C

0.8 x V

≥ 1.2V, I

SOURCE

= 10µA,

RESET asserted

0.8 x V

≥ 1.53V, I

SOURCE

= 200µA,

RESET asserted

0.8 x V

≥ 2.12V, I

SOURCE

= 500µA,

RESET asserted

0.8 x V

≥ 1.71V, I

SINK

= 500µA,

RESET deasserted

0.3

RESET Output Voltage

≥ 2.38V, I

SINK

= 1.2mA,

RESET deasserted

0.3

CT Input Current CT = GND or V

20 nA

0.8 x V

CT Input Voltage

MANUAL RESET INPUT

0.7 x V

MR Input Voltage

MR Minimum Pulse Width t

MPW

1µs

MR Glitch Rejection 200 ns MR to Reset Delay t

MRD

250 ns

MR Pullup Resistance 51020kΩ

WATCHDOG TIMER (MAX6864–MAX6869)

0.7 x V

WDI Input Voltage

WDI Input Current WDI = GND or V

20 nA

WDI Pulse Width t

WDI

(Note 3) 150 ns S 1.5 3.3

Watchdog Timeout Period t

L95209 487

Note 1: Devices are tested at TA= +25°C. Specifications for TA= -40°C to +85°C are guaranteed by design. Note 2: For the MAX6864–MAX6869, the watchdog period is 1s with t

RISE

and t

FALL

< 50ns.

Note 3: Guaranteed by design.

SYMBOL

TYP MAX

0.2 x V

0.3 x V

7.75

NORMALIZED WATCHDOG TIMEOUT PERIOD

vs. TEMPERATURE

MAX6854 toc04

TEMPERATURE (°C)

NORMALIZED t

603510-15

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.4

-40 85

10 100 1000

MAXIMUM VCC TRANSIENT DURATION

vs. RESET THRESHOLD OVERDRIVE

MAX684 toc05

RESET THRESHOLD OVERDRIVE (mV)

TRANSIENT DURATION (µs)

1000

0.1

100

RESET OCCURS ABOVE THIS LINE

VCC FALLING FROM VTH +100mV

NORMALIZED RESET THRESHOLD VOLTAGE

vs. TEMPERATURE

MAX6854 toc06

TEMPERATURE (°C)

NORMALIZED V

603510-15

0.995

1.000

1.005

1.010

0.990

-40 85

VCC TO RESET DELAY

vs. TEMPERATURE

MAX6854 toc07

TEMPERATURE (°C)

(µs)

603510-15

-40 85

VCC = VTH + 100mV TO VTH - 100mV

MAX6854–MAX6869

Nanopower µP Supervisory Circuits with Optional Manual Reset, Watchdog Timer

4 _______________________________________________________________________________________

Typical Operating Characteristics

= +2.5V, TA= +25°C, unless otherwise noted.)

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6854 toc01

VCC (V)

0.1

1.0

10.0

(µA)

5.04.53.5 4.02.0 2.5 3.01.51.0 5.5

VTH = 2.23V

TA = +85°C

TA = +25°C

TA = -40°C

SUPPLY CURRENT

vs. TEMPERATURE

MAX6854 toc02

TEMPERATURE (°C)

(µA)

603510-15

0.12

0.14

0.16

0.18

0.20

0.22

0.10

-40 85

RESET IS NOT ASSERTED V

= 1.575V

VCC = 5.5V

VCC = 2.5V

VCC = 3.3V

VCC = 1.8V

NORMALIZED RESET TIMEOUT PERIOD

vs. TEMPERATURE

MAX6854 toc03

TEMPERATURE (°C)

NORMALIZED t

603510-15

0.99

1.00

1.01

1.02

0.98

-40 85

MAX6854–MAX6869

Nanopower µP Supervisory Circuits with

Optional Manual Reset, Watchdog Timer

_______________________________________________________________________________________ 5

OUTPUT LOW VOLTAGE

vs. SINK CURRENT

MAX6854 toc08

SINK

(µA)

(V)

4000300020001000

0.05

0.10

0.15

0.20

0.25

0.30

0 5000

VCC = 1.8V

VCC = 3.3V

VCC = 2.5V

OUTPUT HIGH VOLTAGE

vs. SOURCE CURRENT

MAX6854 toc09

SOURCE

(µA)

OUTPUT HIGH VOLTAGE (V

- V

) (V)

800600400200

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

01000

VCC = 1.8V

VCC = 3.3V

VCC = 2.5V

SUPPLY CURRENT vs. WATCHDOG

SWITCHING FREQUENCY

MAX6854 toc10

WATCHDOG SWITCHING FREQUENCY (Hz)

SUPPLY CURRENT (µA)

1M100k10k1k100

100

0.1 10 10M

VCC = 2.5V

VCC TO RESET DELAY

MAX6854 toc11

10µs/div

200mV/div

1.7V

1.5V

RESET

1V/div

VTH = 1.575V

MANUAL RESET DELAY

MAX6854 toc12

200ns/div

1V/div

RESET

1V/div

MRD

Typical Operating Characteristics (continued)

= +2.5V, TA= +25°C, unless otherwise noted.)

MAX6854–MAX6869

Nanopower µP Supervisory Circuits with Optional Manual Reset, Watchdog Timer

6 _______________________________________________________________________________________

MAX6854/MAX6855/MAX6856 Pin Description

MAX6854/

MAX6856

MAX6855

NAME FUNCTION

1—RESET

Active-Low Open-Drain or Push-Pull Reset Output. RESET transitions from high to low when V

drops below the selected reset threshold or MR is pulled low.

RESET remains low for the reset timeout period after V

exceeds the device reset threshold and MR deasserts. Push-pull RESET outputs are referenced to V

. Open-drain RESET outputs require an external pullup resistor.

2, 4 2, 4 GND Ground. Connect all GND inputs to the same potential.

33MR

Active-Low Manual Reset Input. Drive MR low to initiate a reset. The reset output remains asserted while MR is held low and for the reset timeout period after MR transitions high. Leave MR unconnected or connect to V

if unused. MR is

internally pulled up to V

through 10kΩ.

55V

Supply Voltage. Input for VCC reset monitor. For noisy systems, bypass VCC with a 0.1µF capacitor to GND.

—1RESET

Active-High Push-Pull Reset Output. RESET transitions from low to high when V

drops below the selected reset threshold or MR is pulled low. RESET

remains high for the reset timeout period after V

exceeds the device reset

threshold and MR deasserts. RESET is referenced to V

MAX6857–MAX6860 Pin Description

MAX6857/

MAX6859

MAX6858/

MAX6860

NAME FUNCTION

14RESET

Active-Low Open-Drain or Push-Pull Reset Output. RESET transitions from high to low when V

drops below the selected reset threshold. RESET remains low for

the reset timeout period after V

exceeds the device reset threshold. Push-pull

RESET outputs are referenced to V

. Open-drain RESET outputs require an

external pullup resistor.

25V

Supply Voltage. Input for VCC reset monitor. For noisy systems, bypass VCC with a 0.1µF capacitor to GND.

33GND Ground

4, 5 1, 2 I.C. Internally Connected. For increased noise immunity, connect I.C. to GND.

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