Operating Temperature Range...........................-40°C to +125°C
Storage Temperature Range..............................-65°C to +150°C
Lead Temperature (soldering, 10sec)...............................+300°C
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.
Electrical Characteristics
(V
DD
= +2.7V to +5.5V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are specified at T
A
= +25°C and V
DD
= +5V,
unless otherwise noted.)
PARAMETER
V
DD
Range
Supply Current
SYMBOL
V
DD
I
DD
V
DD
= 5.5V
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= -20°C
T
A
= 0°C
MAX6576
Temperature Sensor
Error (Note 1)
MAX6577
T
A
= +25°C
T
A
= +85°C
T
A
= +125°C
T
A
= -20°C
T
A
= 0°C
T
A
= +25°C
T
A
= +85°C
T
A
= +125°C
MAX6576,
T (temp) in °K,
Figure 1
V
TS1
= GND, V
TS0
= GND
V
TS1
= GND, V
TS0
= V
DD
V
TS1
= V
DD
, V
TS0
= GND
V
TS1
= V
DD
, V
TS0
= V
DD
V
TS1
= GND, V
TS0
= GND
V
TS1
= GND, V
TS0
= V
DD
V
TS1
= V
DD
, V
TS0
= GND
V
TS1
= V
DD
, V
TS0
= V
DD
-7.5
-5.5
-3.0
-4.5
-5.0
-7.5
-6.5
-3.0
-3.5
-4.5
±1.1
±0.9
±0.8
±0.5
±0.5
±1.1
±0.9
±0.8
±0.5
±0.5
10T
40T
160T
640T
4T
1T
T/4
T/16
0.5
V
IL
V
IH
V
OL
OUT Voltage
V
OH
V
DD
> 4.5V, I
SINK
= 3.2mA
V
DD
> 2.7V, I
SINK
= 1.2mA
V
DD
> 4.5V, I
SRC
= 800μA
V
DD
> 2.7V, I
SRC
= 500μA
V
DD
- 1.5
0.8V
DD
2.3
0.4
0.3
V
0.8
V
Hz
µs
CONDITIONS
MIN
2.7
140
TYP
MAX
5.5
250
400
+7.5
+5.5
+3.0
+4.5
+5.0
+7.5
+6.5
+3.0
+3.5
+4.5
°C
°C
UNITS
V
µA
Output Clock Period
t
OUT
Output Clock Frequency
f
OUT
MAX6577,
T (temp) in °K,
Figure 2
OUT Duty Cycle (Note 2)
Time-Select Pin Logic
Levels
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.
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Maxim Integrated
│
2
MAX6576/MAX6577
SOT Temperature Sensors with
Period/Frequency Output
Typical Operating Characteristics
(V
DD
= +5V, T
A
= +25°C, unless otherwise noted.)
MAX6576 toc01
PERCENTAGE OF PARTS SAMPLED (%)
PERCENTAGE OF PARTS SAMPLED (%)
SAMPLE SIZE = 200
30
25
20
15
10
5
0
-5 -4 -3 -2 -1
0
1
2
MAX6576
MAX6577
SAMPLE SIZE = 200
50
40
30
20
10
0
MAX6576
MAX6577
3
4
5
-5 -4 -3 -2 -1
0
1
2
3
4
5
ACCURACY (°C)
ACCURACY (°C)
MAX6576/77toc03
170
SUPPLY CURRENT (µA)
160
150
140
130
120
110
100
MAX6577
MAX6576
1.0
ACCURACY (°C)
0.5
MAX6577
0
-0.5
-1.0
MAX6576
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
THERMAL STEP RESPONSE
IN PERFLUORINATED FLUID
MAX6576/77 toc05
THERMAL STEP RESPONSE
IN STILL AIR
MAX6576/77 toc06
+100°C
+15°C/div
MOUNTED ON 0.75 in.
2
OF 2oz. COPPER
+25°C
5sec/div
+12.5°C/div
MOUNTED ON 0.75 in.
2
OF 2oz. COPPER
+25°C
20sec/div
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Maxim Integrated
│
3
MAX6575 toc04
180
SUPPLY CURRENT vs. TEMPERATURE
1.5
ACCURACY vs. TEMPERATURE
MAX6576 toc02
35
TEMPERATURE ACCURACY
(T
A
= +25°C)
60
TEMPERATURE ACCURACY
(T
A
= +85°C)
+100°C
MAX6576/MAX6577
SOT Temperature Sensors with
Period/Frequency Output
Pin Description
PIN
1
2
3
4, 5
6
NAME
V
DD
GND
N.C.
TS1, TS0
OUT
Positive Supply Voltage
Ground
No Connection. Connect pin to GND or leave open.
Time-Select Pins. TS1 and TS0 set the temperature scale factor by connecting TS1 and TS0 to either V
DD
or GND. See Tables 1 and 2.
Square-Wave Output with a Clock Period Proportional to Absolute Temperature (°K) (MAX6576)
Square-Wave Output with a Clock Frequency Proportional to Absolute Temperature (°K) (MAX6577)
FUNCTION
Table 1. MAX6576 Time-Select Pin
Configuration
TS1
GND
GND
V
DD
V
DD
TS0
GND
V
DD
GND
V
DD
SCALAR MULTIPLIER (μs/°K)
10
40
160
640
Table 2. MAX6577 Time-Select Pin
Configuration
TS1
GND
GND
V
DD
V
DD
TS0
GND
V
DD
GND
V
DD
SCALAR MULTIPLIER (Hz/°K)
4
1
1/4
1/16
Note:
The temperature, in °C, may be calculated as follows:
Note:
The temperature, in °C, may be calculated as follows:
T(
°
C)
PERIOD(µs)
FREQUENCY(µs)
−
273.15
°
K
=
T(
°
C)
−
273.15
°
K
SCALAR MULTIPLIER(µs/
°
K)
SCALAR MULTIPLIER(µs/
°
K)
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.
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
MAX6576 Characteristics
The MAX6576 temperature sensor converts temperature
to period. The output of the device is a free-running, 50%
duty-cycle square wave with a period that is proportional
The MAX6577 temperature sensor converts temperature
to frequency. The output of the device is a free-running,
50% duty-cycle square wave with a frequency that is pro-
portional 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.
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4
MAX6576/MAX6577
SOT Temperature Sensors with
Period/Frequency Output
MAX6576
CLOCK WAVEFORM OUTPUT
MAX6577
CLOCK WAVEFORM OUTPUT
t
OUT
t
OUT
f
OUT
= 1 / t
OUT
f
OUT
(°K)
Figure 1. MAX6576 Timing Diagram
Figure 2. MAX6577 Timing Diagram
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 ambi-
ent 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 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. At room temperature, the universal counter will
display approximately 298Hz.
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
Interfacing with a Microcontroller
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 mini-
mizes 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.
Figure 5 shows the MAX6577 interfaced with an 8051 μC.
In this example, TS1 is tied to ground and TS0 is tied to
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