MAXIM MAX6666

19-2138; Rev 1; 12/03
High-Accuracy PWM Output Temperature
Sensors
Features
♦ Simple Single-Wire PWM Output
♦ ±1.0°C Accuracy at +25°C
♦ High Accuracy
±1°C at TA = +30°C
±2.5°C at TA = +10°C to +50°C
♦ Operate Up to +125°C
♦ Low 200µA Typical Current Consumption
♦ Multiple Package Options
6-Pin SOT23
8-Pin SO
8-Pin µMAX
Temperature (°C) = 235 - (400 x t1) / t2
Where t1 is fixed with a typical value of 10ms and t2 is
modulated by the temperature (Figure 1). The
MAX6666/MAX6667 operate from -40°C to +125°C and are
available in space-saving SOT23 and µMAX packages.
Applications
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
Process Control
MAX6666AUT-T
-40°C to +125°C
6 SOT23-6
Industrial
MAX6666AUA
-40°C to +125°C
8 µMAX
MAX6666ASA
-40°C to +125°C
8 SO
MAX6667AUT-T
-40°C to +125°C
6 SOT23-6
MAX6667AUA
-40°C to +125°C
8 µMAX
MAX6667ASA
-40°C to +125°C
8 SO
HVAC and Environmental Control
Automotive
µP and µC Temperature Monitoring
Pin Configurations
Typical Operating Circuit
TOP VIEW
+3.3V
t1
VCC
t2
µC
MAX6666
MAX6667
DOUT
GND
INPUT TO
TIMER/COUNTER
DOUT
1
VCC
2
GND
3
MAX6666
MAX6667
IC 4
8
IC
7
IC
6
IC
5
IC
µMAX/SO
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX6666/MAX6667
General Description
The MAX6666/MAX6667 are high-accuracy, low-cost,
low-power temperature sensors with a single-wire
output. The MAX6666/MAX6667 convert the ambient
temperature into a ratiometric PWM output with temperature information contained in the duty cycle of the output square wave. The MAX6666 has a push-pull output
and the MAX6667 has an open-drain output.
The MAX6666/MAX6667 operate at supply voltages
from +3V to +5.5V. The typical unloaded supply current
at 5.0V is 200µA. Both devices feature a single-wire
output that minimizes the number of pins necessary to
interface with a microprocessor (µP). The output is a
square wave with a nominal frequency of 35Hz (±20%)
at +25°C. The output format is decoded as follows:
MAX6666/MAX6667
High-Accuracy PWM Output Temperature
Sensors
ABSOLUTE MAXIMUM RATINGS
(Voltages Referenced to GND)
VCC ........................................................................-0.3V to +6.0V
DOUT
MAX6666................................................-0.3V to (VCC + 0.3V)
MAX6667 ..........................................................-0.3V to + 6.0V
DOUT Current ......................................................-1mA to +50mA
Continuous Current into Any Other Terminal....................±20mA
Continuous Power Dissipation (TA = +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C).........695.7mW
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
Operating Temperature Range .........................-40°C to +150°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering,10s).....................................+150°
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
(VCC = +3.0V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.)
PARAMETER
SYMBOL
Supply Voltage Range
VCC
Supply Current
ICC
CONDITIONS
TYP
3.0
VCC = +3.0V to +5.5V
TA = +30°C
Temperature Error
MIN
VCC = +3.3V
200
MAX
UNITS
5.5
V
500
µA
-1
+1
TA = +10°C to +50°C
-2.5
+2.5
TA = 0°C to +100°C
-3.8
+3.8
TA = -25°C to +125°C
-4.8
+4.8
TA = -40°C, VCC = +3.3V
-6
Nominal t1 Pulse Width
+6
10
MAX6666 Output High Voltage
IOH = 800µA
MAX6666 Output Low Voltage
IOL = 800µA
MAX6666 Fall Time
CL = 100pF, RL = ∞
80
MAX6666 Rise Time
CL = 100pF, RL = ∞
80
MAX6667 Output Low Voltage
°C
ms
VCC - 0.4
V
0.4
V
ns
ns
ISINK = 1.6mA
0.4
ISINK = 5.0mA
1.2
V
MAX6667 Fall Time
CL = 100pF, RL = 10kΩ
40
ns
MAX6667 Output Capacitance
CL = 0
15
pF
<0.1
µA
MAX6667 Output Leakage
Power-Supply Rejection Ratio
2
PSRR
VCC = +3.0V to +5.5V
0.3
_______________________________________________________________________________________
1.0
°C/V
High-Accuracy PWM Output Temperature
Sensors
20
30
T2
24
T1
TEMP = -40°C
14
9
20
10
35
60
85
110
3.0
4.5
5.0
SUPPLY VOLTAGE (V)
OUTPUT ACCURACY
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT (µA)
0
-1
130
120
-3
110
100
50
80
VCC = +3.3V
140
-2
110
80
110
140
158
156
154
152
150
148
146
144
142
140
-55
-25
TEMPERATURE (°C)
5
35
95
65
TEMPERATURE (°C)
POWER-SUPPLY REJECTION RATIO
vs. TEMPERATURE
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
125
155
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
POWER-SUPPLY REJECTION
vs. FREQUENCY
MAX6666/7 toc07
0.50
PSRR (°C/V)
50
1.0
MAX6666/7 toc08
20
VCC = +5.5V
160
150
20
SUPPLY CURRENT vs. SUPPLY VOLTAGE
180
170
-10
TEMPERATURE (°C)
190
1
-40
5.5
210
200
MAX6666/7 toc04
2
-10
4.0
TEMPERATURE (°C)
3
-40
3.5
MAX6666/7 toc05
-15
CHANGE IN TEMPERATURE (°C)
-40
SUPPLY CURRENT (µA)
0
MAX6666/7 toc03
29
19
25
10
OUTPUT ACCURACY (°C)
TEMP = +25°C
35
TWO TYPICAL PARTS
34
MAX6666/7 toc06
30
40
39
TIME (ms)
OUTPUT FREQUENCY (Hz)
40
TEMP = +125°C
MAX6666/7 toc02
45
MAX6666/7 toc01
OUTPUT FREQUENCY (Hz)
50
T1 AND T2 TIMES
vs. TEMPERATURE
OUTPUT FREQUENCY vs. SUPPLY VOLTAGE
OUTPUT FREQUENCY vs. TEMPERATURE
0.5
0
-0.5
0.05
VAC = 100mVp-p
0
-1.0
-40
-15
10
35
60
TEMPERATURE (°C)
85
110
0.01
0.1
1
10
100
1k
10k
FREQUENCY (Hz)
_______________________________________________________________________________________
3
MAX6666/MAX6667
Typical Operating Characteristics
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
MAX6666
OUTPUT RISE AND FALL TIMES
vs. CAPACITIVE LOADS
MAX6666
OUTPUT FALL TIME
MAX6666/7 toc09
1000
FALL TIME
800
TIME (ns)
1V/div
MAX6666/7 toc10
1200
CLOAD = 100pF
RL = 100kΩ
RISE TIME
600
400
200
0
0
40ns/div
300
600
900
1200
1500
CLOAD (pF)
OUTPUT LOW VOLTAGE
vs. TEMPERATURE
0.6
0.5
0.4
ISINK = 1.5mA
0.3
0.2
ISINK = 1mA
0.1
0
3.25
MAX6666/7 toc12
ISINK = 5mA
0.7
3.30
OUTPUT HIGH VOLTAGE (V)
0.9
0.8
OUTPUT HIGH VOLTAGE
VS. TEMPERATURE
MAX6666/7 toc11
1.0
OUTPUT LOW VOLTAGE (V)
MAX6666/MAX6667
High-Accuracy PWM Output Temperature
Sensors
VCC = +3.3V
ISOURCE = 800µA
3.20
3.15
3.10
3.05
3.00
-40 -20
0
20
40
60
80 100 120 140
TEMPERATURE (°C)
-40 -20
0
20
40
60
80 100 120 140
TEMPERATURE (°C)
Pin Description
PIN
NAME
4
µMAX/SO
SOT23
1
1
2
2
VCC
3
3
GND
4–8
4, 5, 6
IC
DOUT
FUNCTION
Digital Output Pin. The pulse width of the output waveform is modulated by the
temperature.
Supply Voltage
Ground
Internally Connected. Leave unconnected or connect to GND.
_______________________________________________________________________________________
High-Accuracy PWM Output Temperature
Sensors
Temperature (°C) = +235 - (400 x t1) / t2
The µC or µP measures the output of the MAX6666/
MAX6667 by counting t 1 and t2 and computing the
temperature based on their ratio. The resolution of the
count is a function of the processor clock frequency
and the resolution of the counter. The MAX6666/
MAX6667 have a resolution of approximately 11 bits.
Always use the same clock for t1 and t2 counters so
that the temperature is strictly based on a ratio of the
two times, thus eliminating errors due to different
clocks’ frequencies.
The MAX6666 (Figure 2a) has a push-pull output and
provides Rail-to Rail® output drive. The ability to source
and sink current allows the MAX6666 to drive capacitive loads up to 10nF with less than 1°C error.
The MAX6667 (Figure 2b) has an open-drain output.
The output capacitance should be minimized in
MAX6667 applications because the sourcing current is
set by the pullup resistor. If the output capacitance
becomes too large, lengthy rise and fall times distort
the pulse width, resulting in inaccurate measurements.
Applications Information
Accurate temperature monitoring requires a good thermal contact between the MAX6666/MAX6667 and the
object being monitored. A precise temperature measurement depends on the thermal resistance between
the object being monitored and the MAX6666 die. Heat
flows in and out of plastic packages primarily through
the leads. For the best thermal contact, connect all
unused pins to ground. If the sensor is intended to
measure the temperature of a heat-generating component on the circuit board, mount the device as close as
possible to that component and share the ground
traces (if they are not too noisy) with the component.
This maximizes the heat transfer from the component to
the sensor.
t1
t2
Figure 1. MAX6666/MAX6667 PWM Output
Power-Supply Bypassing
The MAX6666/MAX6667 operate from a +3V to +5.5V
supply. If a noisy power-supply line is used, bypass
VCC to GND with a 0.1µF capacitor.
Power Supply from µP Port Pin
The low quiescent current of the MAX6666/MAX6667
enables it to be powered from a logic line, which meets
the requirements for supply voltage range. This provides a simple shutdown function to totally eliminate
quiescent current by taking the logic line low. The logic
line must be able to withstand the 0.1µF power-supply
bypass capacitance.
Galvanic Isolation
Use an optocoupler to isolate the MAX6666/MAX6667
whenever a high common-mode voltage is present.
Because some optocouplers have turn-off times that
are much longer than their turn-on times, choose an
optocoupler with equal turn-on and turn-off times.
Unequal turn-on/turn-off times produce an error in the
temperature reading.
Thermal Considerations
Self-heating may cause the temperature measurement
accuracy of the MAX6666/MAX6667 to degrade in
some applications. The quiescent dissipation and the
power dissipated by the digital output may cause
errors in obtaining the accurate temperature measurement. The temperature errors depend on the thermal
conductivity of the package (SOT23, 140°C/W; 8-pin
SO, 170°C/W; 8-pin µMAX, 242°C/W), the mounting
technique, and the airflow. Static dissipation in the
MAX6666/MAX6667 is typically 4.5mW operating at 5V
with no load. As a worst-case example, consider the
MAX6667 and its maximum rated load of 5mA and
assume a maximum output voltage of 0.8V adds 4mW
power dissipation. In an 8-pin µMAX, this would result
in a temperature rise of 0.004 ✕ 242 or approximately
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
_______________________________________________________________________________________
5
MAX6666/MAX6667
Detailed Description
The MAX6666/MAX6667 are high-accuracy, low-cost,
low current (200µA typ) temperature sensors ideal for
interfacing with µCs or µPs. The MAX6666/MAX6667
convert the ambient temperature into a ratiometric
PWM output at a nominal frequency of 35Hz (±20%) at
+25°C.
The time periods, t1 (high) and t2 (low) (Figure 1), are
easily read by the µP’s timer/counter port. To calculate
the temperature, use the expression below:
VCC
VCC
+3.3V
2.5V
P
DOUT
DOUT
5.1kΩ
MAX6667
N
N
DOUT
TO LOGIC GATE INPUT
GND
(a)
(b)
Figure 2. MAX6666/MAX6667 Output Configuration
MAX6666
TEMPERATURE ERROR vs. LOAD CURRENT
Figure 4. Low-Voltage Logic
Pin Configurations (continued)
3.5
TOP VIEW
3.0
TEMPERATURE ERROR (°C)
MAX6666/MAX6667
High-Accuracy PWM Output Temperature
Sensors
µMAX
2.5
DOUT
SO
1
6
IC
5
IC
4
IC
2.0
VCC 2
1.5
MAX6666
MAX6667
1.0
SOT23-6
GND 3
0.5
0
0
2
4
6
8
10
SOT23
LOAD CURRENT (mA)
Figure 3. MAX6666 Temperature Error Due to Load Current
Chip Information
1°C. Use Figure 3 to estimate the temperature error
with respect to the MAX6666 packages.
TRANSISTOR COUNT: 6479
PROCESS: BiCMOS
Low-Voltage Logic
Use the MAX6667 open-drain output to drive low-voltage devices. As shown in Figure 4, connect a pullup
resistor from the low-voltage logic supply to the
MAX6667 output. Limit the resistor’s current to about
1mA, thus maintaining an output low logic level of less
than 200mV.
6
_______________________________________________________________________________________
High-Accuracy PWM Output Temperature
Sensors
6LSOT.EPS
PACKAGE OUTLINE, SOT-23, 6L
4X S
8
8
INCHES
DIM
A
A1
A2
b
E
ÿ 0.50±0.1
H
c
D
e
E
H
0.6±0.1
L
1
1
α
0.6±0.1
S
BOTTOM VIEW
D
MIN
0.002
0.030
MAX
0.043
0.006
0.037
0.010
0.014
0.005
0.007
0.116
0.120
0.0256 BSC
0.116
0.120
0.188
0.198
0.016
0.026
6∞
0∞
0.0207 BSC
1
1
8LUMAXD.EPS
F
21-0058
MILLIMETERS
MAX
MIN
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
5.03
4.78
0.41
0.66
0∞
6∞
0.5250 BSC
TOP VIEW
A1
A2
A
α
c
e
FRONT VIEW
b
L
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0036
REV.
J
1
1
_______________________________________________________________________________________
7
MAX6666/MAX6667
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.)
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.)
DIM
A
A1
B
C
e
E
H
L
N
E
H
INCHES
MILLIMETERS
MAX
MIN
0.053
0.069
0.004
0.010
0.014
0.019
0.007
0.010
0.050 BSC
0.150
0.157
0.228
0.244
0.016
0.050
MAX
MIN
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
1.27 BSC
3.80
4.00
5.80
6.20
0.40
SOICN .EPS
MAX6666/MAX6667
High-Accuracy PWM Output Temperature
Sensors
1.27
VARIATIONS:
1
INCHES
TOP VIEW
DIM
D
D
D
MIN
0.189
0.337
0.386
MAX
0.197
0.344
0.394
MILLIMETERS
MIN
4.80
8.55
9.80
MAX
5.00
8.75
10.00
N MS012
8
AA
14
AB
16
AC
D
A
B
e
C
0∞-8∞
A1
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
21-0041
REV.
B
1
1
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 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.