MAX6575L Datasheet, PDF (5/12 Pages) Maxim Integrated Products – SOT Temperature Sensor with Multidrop Single-Wire Digital Interface

SOT Temperature Sensor with
Multidrop Single-Wire Digital Interface
Table 2. Allowable Temperature Differential (°C)
TIMEOUT
MULTIPLIER
5
MAX6575L
20
40
80
5
>165
>165
>165
20
95.5
>165
40
132.0
80
160
320
480
640
160
>165
>165
>165
153.5
MAX6575H
320
480
>165
>165
>165
>165
>165
>165
>165
>165
>165
>165
70.2
640
>165
>165
>165
>165
>165
>165
37.9
Table 3. Typical Peak Noise Amplitude
PARAMETER
MAX6575L
Timeout
Multiplier
5
20
40
Noise
Amplitude
(°C)
±0.33
±0.15
±0.15
MAX6575H
80
160
320
480
640
±0.098
±0.091
±0.063
±0.043
±0.037
Time-Select Pins (TS1, TS0)
Table 1 shows the configuration of the Time-select pins
for the MAX6575L/H. Each device allows four selec-
table timeout multipliers intended to prevent overlap-
ping when multiple devices are used on the same I/O
line. Tie TS1 and TS0 to either GND or V_DD to select the
desired temperature multiplier.
To monitor several chips on the same I/O line, different
timeout multipliers should be selected using the TS1
and TS0 pins. The timeout periods are then scaled so
that the response times will not overlap (see Timeout
Selection).
Applications Information
Timeout Selection
Under extreme temperature conditions, it is possible for
an overlap to occur between the timeout delays of dif-
ferent sensors in a multidrop configuration. This overlap
can occur only if the temperature differential recorded
between two devices is very large. Timeout overlaps
can be avoided in multidrop configurations by selecting
the appropriate timeout multipliers. Table 2 illustrates
the allowable temperature differential between devices
when the maximum error is present on each device.
Allowable temperature differentials greater than 165°C
indicate no overlap.
For example, if the maximum temperature differential in
a system is 80°C, the only combinations of timeout multi-
pliers that could result in timeout overlap would be a
320:480µs/°K (70.2°C) or a 480:640µs/°K (37.9°C) com-
bination. As long as these combinations of timeout multi-
pliers are not used in the same multidrop configuration,
no overlap can occur. Thus, seven MAX6575L/H parts
can be used in the same multidrop configuration if the
maximum temperature differential between parts is
80°C. A similar analysis shows that four MAX6575L/H
parts can be used when the maximum temperature dif-
ferential extends over the entire 165°C range of the part.
Noise Considerations
The accuracy of the MAX6575L/H timeout delay is sus-
ceptible to noise generated both internally and exter-
nally. The effects of external noise can be minimized by
placing a 0.1µF ceramic bypass capacitor close to the
device’s supply pin. Internal noise is inherent in the
operation of the device and is detailed in Table 3.
Internal averaging minimizes the effect of this noise when
using longer timeout multipliers. The effects of this noise
are included in the overall accuracy of the device as
specified in the Electrical Characteristics table.
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