Operating Temperature Range ......................... -40°C to +125°C
Storage Temperature Range ............................ -65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) ................................. +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
CC
= 1.8V to 3.6V (MAX6676AUT3/MAX6677AUT3), V
CC
= 3.6V to 5.5V (MAX6676AUT5), T
A
= -40°C to +125°C, unless otherwise
noted. Typical values are at V
CC
= 3.0V (MAX6676AUT3/MAX6677AUT3), V
CC
= 5.0V (MAX6676AUT5), T
A
= +25°C.)
PARAMETER
Supply Voltage Range
Supply Current
SYMBOL
V
CC
I
CC
CONDITIONS
MAX6676AUT3/MAX6677AUT3
MAX6676AUT5
R
L
= ∞
T
A
= +25°C
Temperature Error
T
A
= 0°C to +85°C
T
A
= -20°C to +100°C
T
A
= -40°C to +125°C
Nominal t
1
Pulse Width
Output High Voltage
Output Leakage Current
Output Low Voltage
Fall Time
Rise Time
Digital Output Capacitance
Power-Supply Rejection Ratio
V
OL
t
F
t
R
C
OUT
PSRR
V
CC
= 1.8V - 3.6V
-1.2
V
OH
I
OH
= 800µA, MAX6677
V
OUT
= V
CC
I
OL
= 3mA
C
L
= 100pF, R
L
= 10kΩ
MAX6676, C
L
= 15pF, R
L
= 10kW
MAX6677, C
L
= 100pF, R
L
= 10kW
20
300
30
15
+0.4
+1.2
V
CC
-
0.3
0.1
0.3
-1.5
-3.0
-4.2
-5.5
240
MIN
1.8
3.6
80
TYP
MAX
3.6
5.5
200
+1.5
+3.0
+4.2
+5.5
µs
V
µA
V
ns
ns
pF
°C/V
°C
UNITS
V
µA
Note 1:
Parts are tested at +25°C. Specifications are guaranteed by design over temperature.
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Maxim Integrated
│
2
MAX6676/MAX6677
Low-Voltage, 1.8kHz PWM
Output Temperature Sensors
Typical Operating Characteristics
(V
CC
= 3.0V, T
A
= +25°C, unless otherwise noted.)
MAX6676 toc01
MAX6676 toc02
OUTPUT FREQUENCY (kHz)
OUTPUT FREQUENCY (Hz)
2.5
2.25
TEMP = +125°C
2.00
TEMP = +25°C
TIME (s)
400
350
300
250
t
2
2.0
1.5
1.75
t
1
1.0
-40
-15
10
35
60
85
110
1.50
TEMP = -40°C
1.8
2.1
2.4
2.7
3.0
3.3
3.6
SUPPLY VOLTAGE (V)
200
-40
-15
10
35
60
85
110
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT ACCURACY
vs. TEMPERATURE
MAX6676 toc04
MAX6676 toc05
OUTPUT ACCURACY (C)
SUPPLY CURRENT (µA)
1
-1
-3
-5
400
300
200
100
V
CC
= 3.6V
SUPPLY CURRENT (µA)
3
500
400
350
300
250
200
150
100
50
0
1.8
NO PULLUP
2.1
2.4
2.7
3.0
3.3
5.1kΩ PULLUP
V
CC
= 3.0V
V
CC
= 1.8V
5.1kΩ PULLUP RESISTOR
-40
-15
10
35
60
85
110
0
-40
-15
10
35
60
85
110
3.6
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
MAX6676 toc07
MAX6676 toc08
CHANGE IN TEMPERATURE (C)
1
0
-1
-2
-3
-4
-5
V
AC
= 100mV
P-P
1
10
100
FREQUENCY (Hz)
1k
0.5
PSRR (C/V)
0
1V/div
-0.5
0V
-1.0
-50
-25
0
25
50
75
100
125
-6
10k
TEMPERATURE (°C)
10ns/div
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Maxim Integrated
│
3
MAX6676 toc09
1.0
POWER-SUPPLY REJECTION RATIO
vs. TEMPERATURE
2
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
OUTPUT FALL TIME
(C
L
= 100pF, R
L
= 100kΩ)
MAX6676 toc06
5
600
MAX6676AUT3 SUPPLY CURRENT
vs. TEMPERATURE
450
MAX6676AUT3 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6676 toc03
3.0
OUTPUT FREQUENCY
vs. TEMPERATURE
2.50
MAX6676AUT3 OUTPUT FREQUENCY
vs. SUPPLY VOLTAGE
450
t
1
AND t
2
TIMES
vs. TEMPERATURE
MAX6676/MAX6677
Low-Voltage, 1.8kHz PWM
Output Temperature Sensors
Typical Operating Characteristics (continued)
(V
CC
= 3.0V, T
A
= +25°C, unless otherwise noted.)
MAX6677 OUTPUT RISE TIME
C
LOAD
= 100pF
R
L
= 100kΩ
1V/div
MAX6676 toc10
MAX6677 OUTPUT RISE AND FALL TIMES
vs. CAPACITIVE LOAD
MAX6676 toc11
200
160
120
80
40
0
RISE
0
TIME (ns)
FALL
0
100
200
300
C
LOAD
(pF)
400
500
600
40ns/div
MAX6676 toc12
I
SOURCE
= 800µA
3.25
OUTPUT LOW VOLTAGE (mV)
OUTPUT HIGH VOLTAGE (V)
300
250
200
150
100
50
I
SINK
= 5mA
3.00
2.75
I
SINK
= 1.5mA
I
SINK
= 1mA
2.50
-40
-15
10
35
60
85
110
0
-40
-5
30
65
100
TEMPERATURE (°C)
TEMPERATURE (°C)
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Maxim Integrated
│
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MAX6676 toc13
3.50
MAX6677 OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
MAX6677 OUTPUT LOW VOLTAGE
vs. TEMPERATURE
350
MAX6676/MAX6677
Low-Voltage, 1.8kHz PWM
Output Temperature Sensors
Applications Information
FUNCTION
Pin Description
PIN
1
2, 4, 5, 6
3
NAME
DOUT
GND
V
CC
Digital Output Pin. The duty
cycle of the output waveform is
modulated by temperature
Ground. All four ground pins
must be connected to GND
Supply Voltage. Bypass V
CC
to
GND with a 0.1µF capacitor.
Detailed Description
Accurate temperature monitoring requires a good
thermal contact between the MAX6676/MAX6677
and the object being monitored. A precise tempera-
ture measurement depends on the thermal resistance
between the object being monitored and the MAX6676/
MAX6677 die. Heat flows in and out of plastic packages
primarily through the leads. If the sensor is intended to
measure the temperature of a heat-generating compo-
nent 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 maxi-
mizes the heat transfer from the component to the sensor.
The MAX6676/MAX6677 are high-accuracy, low-current
(80µA, typ) temperature sensors ideal for interfacing with
µCs or µPs. The MAX6676/MAX6677 convert the ambient
temperature into a ratiometric PWM output at a nominal
frequency of 1.8kHz (±20%) at +25°C.
The time periods, t1 (low) and t2 (high) (Figure 1), are
easily read by a µP’s timer/counter port. To calculate the
temperature, use the following expression:
Temperature (°C) = 398.15 x (t
1
/
t
2
) - 273.15
The µC or µP measures the output of the MAX6676/
MAX6677 by counting t
1
and t
2
and computing the tem-
perature based on their ratio. The resolution of the count
is a function of the processor clock frequency and the
resolution of the counter. Always use the same clock for
t
1
and t
2
counters so that the temperature is strictly based
on a ratio of the two times, thus eliminating errors due to
different clocks’ frequencies.
The MAX6677 (Figure 2a) has a push-pull output with
full CMOS output swings. The ability to source and sink
current allows the MAX6677 to drive capacitive loads up
to 100pF with less than 1°C error.
The MAX6676 (Figure 2b) has an open-drain output. The
output capacitance should be minimized in MAX6676
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.
Power Supply from µP Port Pin
The low quiescent current of the MAX6676/MAX6677
enables them 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 0.1µ power-supply
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