Rainbow Electronics MAX6575H User Manual

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General Description

The MAX6575L/H is a low-cost, low-current temperature sensor with a single-wire digital interface. It features accuracy of ±3°C at +25°C, ±4.5°C at +85°C, and ±5°C at +125°C. The MAX6575L/H is a monostable, externally triggered temperature sensor that allows a microprocessor (µP) to interface with up to eight temperature sensors using a single control line. Temperatures are sensed by measuring the time delay between the falling edge of the external triggering pulse and the falling edge of the subsequent pulse delays reported from the devices. Different sensors on the same I/O line use different timeout multipliers to avoid overlapping signals.

The MAX6575L/H features eight different timeout multipliers; these are selectable by using the two time-select pins on each device and choosing the “L” or “H” version. The “L” version provides four delay ranges less than 50ms. The “H” version provides four delay ranges greater than 50ms. The MAX6575L/H is available in a space-saving 6-pin SOT23 package.

Applications

Critical µP and µC Temperature Monitoring Portable Battery-Powered Equipment Cell Phones Battery Packs Hard Drives/Tape Drives Networking and Telecom Equipment Medical Equipment Automotive

Features

♦ Simple Single-Wire Interface to µP or µC ♦ Multidrop up to Eight Sensors on One Wire ♦ ±0.8°C Accuracy at +25°C (±3°C max) ♦ Operates from +2.7V to +5.5V Supply Voltage ♦ Low 150µA (typ) Supply Current ♦ Standard Operating Temperature Range:

-40°C to +125°C

♦ Small 6-Pin SOT23 Package

MAX6575L/H

SOT Temperature Sensor with

Multidrop Single-Wire Digital Interface

________________________________________________________________

Maxim Integrated Products

19-1485; Rev 0; 4/99

PART

MAX6575LZUT -40°C to +125°C

TEMP. RANGE

PIN-

PACKAGE

6 SOT23

Ordering Information

Selector Guide

SOT

TOP MARK

AABG

MAX6575HZUT AABH-40°C to +125°C 6 SOT23

TIMEOUT MULTIPLIERS

(µs/°K)

MAX6575L 5, 20, 40, 80

MAX6575H 160, 320, 480, 640

PART

Pin Configurations appear at end of data sheet.

GND

TS0

TS1

I/O

0.1µF

MAX6575L

CHIP #1 CHIP #8

10k

+2.7V TO +5.5V

GND

TS0

TS1

I/O

0.1µF

MAX6575H

µP

I/O

GND

Typical Operating Circuit

MAX6575L/H

SOT Temperature Sensor with Multidrop Single-Wire Digital Interface

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= +2.7V to +5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are specified at TA= +25°C and VDD= +5V, unless otherwise noted.)

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.

Note 1: See Temperature Accuracy histograms in

Typical Operating Characteristics

Note 2: Guaranteed by design. Not production tested. Note 3: Limit maximum start pulse at 1ms to avoid timing overlap. Note 4: If no reset pulse is applied.

Terminal Voltage (with respect to GND)

........................................................................-0.3V to +6V

TS1, TS0..................................................-0.3V to (V

+ 0.3V)

I/O..........................................................................-0.3V to +6V

Input/Output Current, All Pins...........................................±20mA

Continuous Power Dissipation (T

= +70°C)

6-Pin SOT23 (derate 7.10mW/°C above +70°C)...........571mW

Operating Temperature Range .........................-40°C to +125°C

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

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

VDD= 5.5V

VDD> 2.7V, I

SINK

= 1.2mA

VDD> 4.5V, I

SINK

= 3.2mA

Figure 1

Figure 1, TA= +25°C

CONDITIONS

V2.3V

I/O Input Voltage High

V0.8V

I/O Input Voltage Low

0.3

I/O Output Voltage Low

0.4

2.3V

Time-Select Pin Logic Levels V

0.8V

ns500Glitch Immunity on I/O Input

ms520t

READY

Delay Time from Trigger to Ready (Note 4)

µs2.5t

START

Start Pulse (Note 3)

-7.5 ±1.1 +7.5

µA

150 250

V2.7 5.5V

VDDRange Supply Current

µs10t

SETUP

Setup Time

µs5Tt

L1-8

Output Pulse Low Time

5Tt

°C

Temperature Sensor Error (Note 1)

-5.5 ±0.9 +5.5

-3.0 ±0.8 +3.0

-4.5 ±0.5 +4.5

-5.0 ±0.5 +5.0

UNITSMIN TYP MAXSYMBOLPARAMETER

TA= -20°C TA= 0°C TA= +25°C TA= +85°C TA= +125°C

Figure 1 ms4.6 16.0t

RESET

Reset Pulse Width (Note 2)

TS1

= GND, V

TS0

= GND

TS1

= GND, V

TS0

= V

20Tt

TS1

= VDD, V

TS0

= GND

MAX6575L, T (temp) in °K, Figure 1

40Tt

Output Pulse Delay

TS1

= VDD, V

TS0

= V

80Tt

TS1

= GND, V

TS0

= GND 160Tt

TS1

= GND, V

TS0

= V

320Tt

TS1

= VDD, V

TS0

= GND

MAX6575H, T (temp) in °K, Figure 1

480Tt

TS1

= VDD, V

TS0

= V

µs

640Tt

TA= -40°C to +85°C TA= -40°C to +125°C 400

MAX6575L/H

SOT Temperature Sensor with

Multidrop Single-Wire Digital Interface

_______________________________________________________________________________________

-5 -3 -2-4 -1012345

TEMPERATURE ACCURACY

= +25°C)

MAX6575 toc01

ACCURACY (°C)

PERCENTAGE OF PARTS SAMPLED (%)

SAMPLE SIZE = 200

15 10

-5 -3 -2-4 -1 0 1 2 3 4 5

TEMPERATURE ACCURACY

= +85°C)

MAX6575 toc02

ACCURACY (°C)

PERCENTAGE OF PARTS SAMPLED (%)

SAMPLE SIZE = 200

-1.0

-0.5

0.5

1.0

1.5

-40 -10 5-25 20 35 50 65 80 95 110 125

ACCURACY vs. TEMPERATURE

MAX6576 toc3a

TEMPERATURE (°C)

ACCURACY (°C)

120

140

130

160

150

180

170

190

-40 -10 5 20-25 35 50 65 80 95 110 125

SUPPLY CURRENT vs. TEMPERATURE

MAX6575L/H-03

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

+15°C/div

+100°C

+25°C

THERMAL STEP RESPONSE IN PERFLUORINATED FLUID

MAX6575L/H-04

5sec/div

MOUNTED ON 0.75 in.

OF 2oz. COPPER

+12.5°C/div

+100°C

+25°C

THERMAL STEP RESPONSE

IN STILL AIR

MAX6575L/H-05

20sec/div

MOUNTED ON 0.75 in.

OF 2oz. COPPER

Typical Operating Characteristics

(VDD= +5V, TA = +25°C, unless otherwise noted.)

Pin Description

Bidirectional Interface Pin. A time delay between when the part is initiated externally by pulling I/O low and when the part subsequently pulls I/O low, is proportional to absolute temperature (°K).

I/O6

Time-Select Pins. Set the time delay factor by connecting TS1 and TS0 to either VDDor GND. See Table 1.TS0, TS14, 5

No Connect. Connect pin to GND or leave open.N.C.3

GroundGND2

FUNCTIONPIN NAME

Positive Supply VoltageV

MAX6575L/H

SOT Temperature Sensor with Multidrop Single-Wire Digital Interface

4 _______________________________________________________________________________________

_______________Detailed Description

The MAX6575L/H low-cost, low-current (150µA typ) temperature sensor is ideal for interfacing with microcontrollers or microprocessors. The MAX6575L/H is a monostable, externally triggered temperature sensor that uses a Temp→Delay conversion to communicate with a µP over a single I/O line. Time-select pins (TS1, TS0) permit the internal temperature-controlled oscillator (TCO) to be scaled by four preset timeout multipliers, allowing eight separate temperature sensors to share one I/O line. Different sensors on the same I/O line will use different timeout multipliers to avoid overlapping signals.

Operating the MAX6575L/H

Figure 1 illustrates the timing for the MAX6575L/H. When the device is powered up, it assumes a ready state where it awaits an external trigger at the I/O pin. The I/O pin of the MAX6575L/H has an open-drain output structure that requires a pull-up resistor to maintain the proper logic levels. Once the I/O pin is pulled low and then released, control of the I/O pin is transferred to the MAX6575L/H. The temperature conversion begins on the falling edge of the externally triggered pulse. The I/O line is pulled low at a later time. That time is determined by the device temperature and the Time Select pins (TS1, TS0). The I/O line remains low for 5Tµs, where T is the temperature in degrees Kelvin. The temperature of the device is represented by the edgeto-edge delay of the externally triggered pulse and the falling edge of the subsequent pulse originating from the device. The device can be manually reset by pulling the I/O line low for more than t

RESET

(16ms

max). The device will automatically reset after a maxi-

mum delay of 520ms, at which point it will again be in a ready state awaiting a start pulse.

Definition of Terms: t

RESET

: Time I/O must be externally pulled low to guar-

antee the MAX6575L/H is in a ready state awaiting external trigger. (Part will assume a ready state after 520ms without a reset pulse.)

SETUP

: Time I/O must be high prior to a start pulse.

START

: Trigger pulse which starts the on-chip timing

sequence on its falling edge.

tDx: Timing delay between the falling edge of the

start pulse and the falling edge initiated by

CHIP#x. tLx: I/O pulse low time (5Tµs). t

READY

: Time after falling edge of start pulse when the

MAX6575L/H will reset itself and await the next

external trigger. The temperature, in degrees Celsius, may be calculat-

ed as follows:

T(°C) = [tDx(µs) / timeout multiplier(µs/°K)] - 273.15°K

GND 5GND GND 20V

40GND

TIME-SELECT PINS

TS0TS1 MAX6575L

160

MAX6575H

320 480

80 640V

Figure 1. Timing Diagram

Table 1. Time-Select Pin Configuration

TIMEOUT MULTIPLIERS

(µs/°K)

CHIP# 1 RESPONSE

APPLIED START

SETUP

START

RESET

PULSE

CHIP# 2 RESPONSE

READY

CHIP# 3 RESPONSE

CHIP# 4 RESPONSE

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