Rainbow Electronics MAX6577 User Manual

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General Description

The MAX6576/MAX6577 are low-cost, low-current tem­perature sensors with a single-wire output. The MAX6576
converts the ambient temperature into a square wave
with a period proportional to absolute temperature (°K).
The MAX6577 converts the ambient temperature into a
square wave with a frequency proportional to absolute
temperature. The MAX6576 offers accuracy of ±3°C at
+25°C, ±4.5°C at +85°C, and ±5°C at +125°C. The
MAX6577 offers accuracy of ±3°C at +25°C, ±3.5°C at
+85°C, and ±4.5°C at +125°C.

Both devices feature a single-wire output that minimizes
the number of pins necessary to interface with a micro­processor. The period/frequency range of the output
square wave can be selected by hard-wiring the two
time-select pins (TS0, TS1) to either VDDor GND. The
MAX6576/MAX6577 are available in space-saving 6-pin
SOT23 packages.

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 Output
♦ Two Output Types Available

Temperature to Period (µs) (MAX6576)
Temperature to Frequency (Hz) (MAX6577)

♦ ±0.8°C Accuracy at +25°C (±3°C max)
♦ No External Components
♦ Operates from +2.7V to +5.5V Supply Voltage
♦ Low 140µA Typical Supply Current
♦ Standard Operating Temperature Range:

-40°C to +125°C

♦ Small 6-Pin SOT23 Package

MAX6576/MAX6577

SOT Temperature Sensors with

Period/Frequency Output

________________________________________________________________

Maxim Integrated Products

1

+2.7V TO +5.5V

GND

TS0

TS1

OUT

0.1µF

0.1µF

V

DD

MAX6576
MAX6577

µP

GND

I/O

V

CC

19-1484; Rev 0; 4/99

PART

MAX6576ZUT
MAX6577ZUT

-40°C to +125°C

-40°C to +125°C

TEMP. RANGE

PIN-

PACKAGE

6 SOT23
6 SOT23

Typical Operating Circuit

Ordering Information

SOT

TOP MARK

AABI

AABJ

GND

TS0N.C.

16OUT

5 TS1

V

DD

MAX6576
MAX6577

SOT23-6

TOP VIEW

2

34

Pin Configuration

MAX6576/MAX6577

SOT Temperature Sensors with
Period/Frequency Output

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 the Temperature Accuracy histograms in the

Typical Operating Characteristics

.

Note 2: The output duty cycle is guaranteed to be 50% by an internal flip-flop.

Terminal Voltage (with respect to GND)

V

DD

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

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

DD

+ 0.3V)

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

Continuous Power Dissipation (T

A

= +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

MAX6576

VDD= 5.5V

VDD> 2.7V, I

SINK

= 1.2mA

VDD> 4.5V, I

SINK

= 3.2mA

MAX6576,
T (temp) in °K,
Figure 1

MAX6577

CONDITIONS

0.3
V

0.4

V

OL

OUT Voltage

2.3V

IH

V

0.8V

IL

Time-Select Pin Logic
Levels

0.5OUT Duty Cycle (Note 2)

640T

°C

-7.5 ±1.1 +7.5

Temperature Sensor
Error (Note 1)

µA

140 250

I

DD

V2.7 5.5V

DD

VDDRange
Supply Current

160T

40T

µs

10T

t

OUT

Output Clock Period

-3.0 ±0.8 +3.0

-5.5 ±0.9 +5.5

-3.0 ±0.8 +3.0

-7.5 ±1.1 +7.5

-6.5 ±0.9 +6.5

UNITSMIN TYP MAXSYMBOLPARAMETER

TA= -20°C
TA= 0°C
TA= +25°C

TA= -20°C
TA= 0°C
TA= +25°C

V

TS1

= VDD, V

TS0

= V

DD

MAX6577,
T (temp) in °K,
Figure 2

V

TS1

= VDD, V

TS0

= V

DD

T/16

T/4

1T

Hz

4T

f

OUT

Output Clock Frequency

VDD> 4.5V, I

SRC

= 800µA VDD- 1.5

V

OH

VDD> 2.7V, I

SRC

= 500µA 0.8V

DD

V

TS1

= GND, V

TS0

= GND

V

TS1

= GND, V

TS0

= V

DD

V

TS1

= VDD, V

TS0

= GND

V

TS1

= GND, V

TS0

= GND

V

TS1

= GND, V

TS0

= V

DD

V

TS1

= VDD, V

TS0

= GND

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

°C

-3.5 ±0.5 +3.5TA= +85°C

-4.5 ±0.5 +4.5TA= +125°C

TA= +85°C -4.5 ±0.5 +4.5
TA= +125°C -5.0 ±0.5 +5.0

MAX6576/MAX6577

SOT Temperature Sensors with

Period/Frequency Output

_______________________________________________________________________________________

3

0

10

5

15

20

25

30

35

-5 -3 -2-4 -1012345

TEMPERATURE ACCURACY

(T

A

= +25°C)

MAX6576 toc01

ACCURACY (°C)

PERCENTAGE OF PARTS SAMPLED (%)

MAX6576
MAX6577

SAMPLE SIZE = 200

0

20

10

30

40

50

60

-5 -3 -2-4 -1012345

TEMPERATURE ACCURACY

(T

A

= +85°C)

MAX6576 toc01

ACCURACY (°C)

PERCENTAGE OF PARTS SAMPLED (%)

MAX6576
MAX6577

SAMPLE SIZE = 200

100

130
120
110

150
140

170
160

180

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

SUPPLY CURRENT vs. TEMPERATURE

MAX6576/77toc02

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

MAX6577

MAX6576

-1.0

0

-0.5

1.0

0.5

1.5

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

ACCURACY vs. TEMPERATURE

MAX6575 toc04

TEMPERATURE (°C)

ACCURACY (°C)

MAX6576

MAX6577

+15°C/div

+100°C

+25°C

THERMAL STEP RESPONSE
IN PERFLUORINATED FLUID

MAX6576/77 toc05

5sec/div

MOUNTED ON 0.75 in.

2

OF 2oz. COPPER

+12.5°C/div

+100°C

+25°C

THERMAL STEP RESPONSE

IN STILL AIR

MAX6576/77 toc06

20sec/div

MOUNTED ON 0.75 in.

2

OF 2oz. COPPER

Typical Operating Characteristics

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

Table 1. MAX6576 Time-Select Pin
Configuration

Table 2. MAX6577 Time-Select Pin
Configuration

MAX6576/MAX6577

SOT Temperature Sensors with
Period/Frequency Output

4 _______________________________________________________________________________________

Pin Description

Detailed Description

The MAX6576/MAX6577 low-cost, low-current (140µA
typ) temperature sensors are ideal for interfacing with
microcontrollers (µCs) or microprocessors (µPs). The
MAX6576 converts ambient temperature into a 50% duty­cycle square wave with a period proportional to absolute
temperature. The MAX6577 converts ambient tempera­ture into a 50% duty-cycle square wave with a frequency
proportional to absolute temperature. Time-select pins
(TS1, TS0) permit the internal temperature-controlled
oscillator (TCO) to be scaled by four preset multipliers.
The MAX6576/MAX6577 feature a single-wire interface to
minimize the number of port pins necessary for interfac­ing with a µP.

MAX6576 Characteristics

The MAX6576 temperature sensor converts tempera­ture to period. The output of the device is a free­running, 50% duty-cycle square wave with a period that

is proportional to the absolute temperature (°K) of the
device (Figure 1). The MAX6576 has a push/pull CMOS
output with sharp edges. The speed of the output
square wave can be selected by hard-wiring TS1 and
TS0 as shown in Table 1. One of four scaled output
periods can be selected using TS1 and TS0.

MAX6577 Characteristics

The MAX6577 temperature sensor converts tempera­ture to frequency. The output of the device is a free­running, 50% duty-cycle square wave with a frequency
that is proportional to the absolute temperature (°K) of
the device (Figure 2). The MAX6577 has a push/pull
CMOS output with sharp edges. The speed of the out­put square wave can be selected by hard-wiring TS1
and TS0 as shown in Table 2. One of four scaled output
frequencies can be selected using TS1 and TS0.

GND
GND

V

DD

GND

V

DD

GND 10

40

160

V

DD

V

DD

640

TS1 TS0

SCALAR MULTIPLIER

(µs/°K)

Note: The temperature, in °C, may be calculated as follows:

GND
GND

V

DD

GND

V

DD

GND 4

1

1/4

TS1 TS0

SCALAR MULTIPLIER

(Hz/°K)

V

DD

V

DD

1/16

1
2
3

Positive Supply Voltage
Ground
No Connection. Connect pin to GND or leave open.

FUNCTION

4, 5

Time-Select Pins. TS1 and TS0 set the temperature scale factor by connecting TS1 and TS0 to
either VDDor GND. See Tables 1 and 2.

PIN

N.C.

GND

V

DD

NAME

TS1, TS0

Note: The temperature, in °C, may be calculated as follows:

T( C)

period( s)

scalar mulitplier( s/ K)

273.15 K°=

°

−°

µ

µ

T( C)

frequency(Hz)

scalar mulitplier(Hz/ K)

273.15 K°=

°

−°

6

Square-Wave Output with a Clock Frequency Proportional to Absolute Temperature (°K) (MAX6577)

OUT

Square-Wave Output with a Clock Period Proportional to Absolute Temperature (°K) (MAX6576)

Applications Information

Quick-Look Circuits

Figure 3 shows a quick-look application circuit for the
MAX6576 using a universal counter measuring period.
TS1 and TS0 are both tied to ground to select a scalar
multiplier of 10µs/°K. The MAX6576 converts the ambi­ent temperature into a square wave with a period that is
10 times the absolute temperature of the device in µs.
At room temperature, the universal counter will display
approximately 2980µs.

Figure 4 shows a quick-look application circuit for the
MAX6577 using a universal counter measuring frequen­cy. TS1 is tied to ground and TS0 is tied to VDDto
select a scalar multiplier of 1Hz/°K. The MAX6577 con­verts the ambient temperature into a square wave with
a frequency that is equal to the absolute temperature of
the device in Hertz. At room temperature, the universal
counter will display approximately 298Hz.

Interfacing with a Microcontroller

Figure 5 shows the MAX6577 interfaced with an 8051
µC. In this example, TS1 is tied to ground and TS0 is

tied to V

DD

to select a scalar multiplier of 1Hz/°K. The
MAX6577 converts the ambient temperature into a
square wave with a frequency that is equal to the
absolute temperature of the device in Hertz. The 8051
µC reads the frequency of the square-wave output of
the MAX6577 into Timer 0 and displays the temperature
as degrees Celsius in binary on Port 1. Listing 1 pro­vides the code for this application. The interface is simi­lar for the MAX6576, except the µC will perform a
period measurement.

Noise Considerations

The accuracy of the MAX6576/MAX6577 is susceptible
to noise generated both internally and externally. The
effects of external noise can be minimized by placing a

0.1µF ceramic bypass capacitor close to the supply pin
of the devices. Internal noise is inherent in the opera­tion of the devices and is detailed in Table 3. Internal
averaging minimizes the effect of this noise when using
longer scalar timeout multipliers. The effects of this noise
are included in the overall accuracy of the devices as
specified in the

Electrical Characteristics

.

MAX6576/MAX6577

SOT Temperature Sensors with

Period/Frequency Output

_______________________________________________________________________________________ 5

t

OUT

MAX6576

CLOCK WAVEFORM OUTPUT

Figure 1. MAX6576 Timing Diagram Figure 2. MAX6577 Timing Diagram

MAX6577

CLOCK WAVEFORM OUTPUT

t

OUT

f

= 1 / t

OUT

OUT

f

(°K)

OUT

MAX6576/MAX6577

SOT Temperature Sensors with
Period/Frequency Output

6 _______________________________________________________________________________________

GND

TS0
TS1

OUT

0.1µF

V

DD

+2.7V TO +5.5V

UNIVERSAL COUNTER

"FREQUENCY"

MAX6577

Figure 4. MAX6577 Quick-Look Circuit

GND

TS0
TS1

OUT

0.1µF
V

DD

+2.7V TO +5.5V

UNIVERSAL COUNTER

"PERIOD"

MAX6576

Figure 3. MAX6576 Quick-Look Circuit

Figure 5. Interfacing with a µC

Table 3. Typical Peak Noise Amplitude

PARAMETER

Noise Amplitude (°C)

MAX6577

±0.38

MAX6576

±0.17

Scalar Multiplier 10 40

±0.11

160

±0.094

640

±0.13

4

±0.066

1

±0.040

1/4

±0.028

1/16

Chip Information

TRANSISTOR COUNT: 302

+2.7V TO +5.5V

V

MAX6577

TS0
TS1

GND

V

CC

470Ω x 8

P1.0
P1.1
P1.2
P1.3

8051

GND

P1.4
P1.5
P1.6
P1.7

22pF

X1

12MHz

X2

22pF

DD

OUT

0.1µF

T0

MAX6576/MAX6577

SOT Temperature Sensors with

Period/Frequency Output

_______________________________________________________________________________________ 7

Listing 1. 8051 Code Example

MAX6576/MAX6577

SOT Temperature Sensors with
Period/Frequency Output

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.

8

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© 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Listing 1. 8051 Code Example (continued)

6LSOT.EPS

Package Information