SM72480

Manufacturer Part NumberSM72480
ManufacturerTexas Instruments
SM72480 datasheet
 


Specifications of SM72480

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FIGURE 1. SM72480 No Decoupling Required for
Capacitive Loads Less than 1100 pF.
C
Minimum R
LOAD
1.1 nF to 99 nF
100 nF to 999 nF
1.5 kΩ
1 μF
800 Ω
FIGURE 2. SM72480 with series resistor for capacitive
loading greater than 1100 pF.
4.3 VOLTAGE SHIFT
The SM72480 is very linear over temperature and supply
voltage range. Due to the intrinsic behavior of an NMOS/
PMOS rail-to-rail buffer, a slight shift in the output can occur
when the supply voltage is ramped over the operating range
of the device. The location of the shift is determined by the
relative levels of V
and V
. The shift typically occurs
DD
TEMP
when V
− V
= 1.0V.
DD
TEMP
This slight shift (a few millivolts) takes place over a wide
change (approximately 200 mV) in V
DD
shift takes place over a wide temperature change of 5°C to
20°C, V
is always monotonic. The accuracy specifica-
TEMP
tions in the Electrical Characteristics table already includes
this possible shift.
5.0 Mounting and Temperature
Conductivity
The SM72480 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or ce-
mented to a surface.
The best thermal conductivity between the device and the
PCB is achieved by soldering the DAP of the package to the
30142015
thermal pad on the PCB. The temperatures of the lands and
traces to the other leads of the SM72480 will also affect the
temperature reading.
Alternatively, the SM72480 can be mounted inside a sealed-
end metal tube, and can then be dipped into a bath or screwed
into a threaded hole in a tank. As with any IC, the SM72480
and accompanying wiring and circuits must be kept insulated
and dry, to avoid leakage and corrosion. This is especially true
if the circuit may operate at cold temperatures where con-
densation can occur. If moisture creates a short circuit from
the V
TEMP
SM72480 will not be correct. Printed-circuit coatings are often
used to ensure that moisture cannot corrode the leads or cir-
30142033
cuit traces.
S
The thermal resistance junction-to-ambient (θ
3 kΩ
rameter used to calculate the rise of a device junction tem-
perature due to its power dissipation. The equation used to
calculate the rise in the SM72480's die temperature is
where T
is the ambient temperature, I
A
rent, I
is the load current on the output, and V
L
voltage. For example, in an application where T
V
= 5 V, I
DD
= 2 μA, the junction temperature would be 30.021 °C, show-
I
L
ing a self-heating error of only 0.021°C. Since the SM72480's
junction temperature is the actual temperature being mea-
sured, care should be taken to minimize the load current that
the V
TEMP
put is used with a 100 k pull-up resistor, and this output is
or V
. Since the
asserted (low), then for this example the additional contribu-
TEMP
tion is [(152° C/W)x(5V)
heating error of 0.059°C.
resistance of the SM72480.
Device Number
SM72480SD
FIGURE 3. SM72480 Thermal Resistance
13
output to ground or V
, the V
output from the
DD
TEMP
) is the pa-
JA
is the quiescent cur-
Q
is the output
O
= 9 μA, Gain 4, V
= 2231 mV, and
DD
TEMP
output is required to drive. If The OVERTEMP out-
2
/100k] = 0.038°C for a total self-
Figure 3
shows the thermal
NS Package
Thermal
Number
Resistance (θ
SDB06A
152° C/W
www.national.com
= 30 °C,
A
)
JA