MAX6672 MAXIM [Maxim Integrated Products], MAX6672 Datasheet - Page 4

• Manufacturer Part Number: MAX6672
• Description: PWM Output Temperature Sensors in SC70 Packages
• Manufacturer: MAXIM [Maxim Integrated Products]

PWM Output Temperature Sensors
in SC70 Packages
The MAX6672/MAX6673 are low-current (60µA, typ),
local temperature sensors ideal for interfacing with µCs
or µPs. The MAX6672/MAX6673 convert their own tem-
perature into a ratiometric PWM output. The square-
wave output waveform time ratio contains the
temperature information. The output is a square wave
with a nominal frequency of 1.4kHz at +25°C. The tem-
perature is obtained with the following formula:
Where t
temperature. Table 1 lists time ratio vs. temperature.
For temperatures greater than +50°C, the temperature
error is primarily first order and the following equation
can be used:
4
(V
CC
100
_______________________________________________________________________________________
PIN
3, 4
75
50
25
1
2
5
= 3.3V, T
0
1
Temperature (°C) = -200 x (0.85 - t
Temperature (°C) = (425 x t
is a fixed value and t
4
A
THERMAL RESPONSE
IN STIRRED OIL BATH
= +25°C, unless otherwise noted.)
NAME
DOUT
TRANSITION FROM +25°C AIR
TO +100°C STIRRED OIL BATH
GND
N.C.
V
CC
8
TIME (s)
Detailed Description
12
Digital Output Pin. PWM output, open-drain output (MAX6672), or push-pull output (MAX6673).
No Connection. Not internally connected.
Pin 3 and Pin 4 must be tied together and connected to ground.
Positive Supply. Bypass with a 0.1µF capacitor to GND.
+ (425 x t
16
2
is modulated with the
20
1
1
/ t
/ t
2
2
) - 273
) - 273
1
Typical Operating Characteristics (continued)
30
25
20
15
10
/ t
5
0
-50
2
)
V
3
OL
= 0.4V
-25
OUTPUT SINK CURRENT
vs. TEMPERATURE
0
TEMPERATURE (°C)
25
V
V
CC
CC
The MAX6673 has a push-pull output. The rise and fall
times of the MAX6673 output are negligible with
respect to the period; therefore, errors caused by
capacitive loading are minimized.
The output load capacitance should be minimized in
MAX6672 applications because the sourcing current is
set by the pullup resistor. If the output capacitance
becomes too large, unequal rise and fall times distort
the pulse width, thus delivering inaccurate readings.
The Typical Application Circuit shows the MAX6672/
MAX6673 interfaced with a µC. In this example, the
MAX6672/MAX6673 convert the ambient temperature
to a PWM waveform. The µC reads the temperature by
measuring the t
ware. The only timing requirements are that the clock
frequency used for timing measurements is stable and
50
= 5V
= 3.3V
75
FUNCTION
100
125
Applications Information
1
and t
3.0
2.5
2.0
1.5
1.0
0.5
0
-50
2
MAX6673 OUTPUT SOURCE CURRENT
V
Pulse-Width Modulation
periods in software and hard-
OH
-25
= V
CC
Pin Description
- 0.5V
vs. TEMPERATURE
0
TEMPERATURE (°C)
Interfacing with a µC
25
V
V
CC
CC
= 5V
= 3.3V
50
75
100
125