Datasheet

TMP05/TMP06 Data Sheet
Rev. C | Page 14 of 28
One Shot Mode
In one shot mode, the TMP05/TMP06 output one square wave
representing temperature when requested by the microcon-
troller. The microcontroller pulls the OUT pin low and then
releases it to indicate to the TMP05/TMP06 that an output is
required. The time between the OUT pin going low to the time
it is released should be greater than 20 ns. Internal hysteresis in
the OUT pin prevents the TMP05/TMP06 from recognizing
that the pulse is going low (if it is less than 20 ns). The
temperature measurement is output when the OUT line is
released by the microcontroller (see Figure 22).
µCONTROLLER RELEASES
OUT LINE HERE
µCONTROLLER PULLS DOWN
OUT LINE HERE
TEMP MEASUREMENT
T
L
T
H
>20ns
TIME
T
0
03340-019
Figure 22. TMP05/TMP06 One Shot OUT Pin Signal
In the TMP05 one shot mode only, an internal resistor is
switched in series with the pull-up MOSFET. The TMP05 OUT
pin has a push-pull output configuration (see Figure 23).
Therefore, it needs a series resistor to limit the current drawn
on this pin when the user pulls it low to start a temperature
conversion. This series resistance prevents any short circuit
from V
DD
to GND, and, as a result, protects the TMP05 from
short-circuit damage.
TMP05
V+
OUT
5kΩ
03340-016
Figure 23. TMP05 One Shot Mode OUT Pin Configuration
The advantages of the one shot mode include lower average
power consumption, and the microcontroller knowing that the
first low-to-high transition occurs after the microcontroller
releases the OUT pin.
Conversion Rate
In continuously converting and one shot modes, the state of the
CONV/IN pin on power-up determines the rate at which the
TMP05/TMP06 measure temperature. The available conversion
rates are shown in Table 7.
Table 7. Conversion Rates
CONV/IN Pin Conversion Rate T
H
/T
L
(25°C)
Low Quarter period
(T
H
/4, T
L
/4)
8.5/16 (ms)
Floating Nominal 34/65 (ms)
High Double high (T
H
x 2)
Quarter low (T
L
/4)
68/16 (ms)
The TMP05 (push-pull output) advantage when using the high
state conversion rate (double high/quarter low) is lower power
consumption. However, the trade-off is loss of resolution on the
low time. Depending on the state of the CONV/IN pin, two
different temperature equations must be used.
The temperature equation for the low and floating states’
conversion rates is
Temperature (°C) = 421 − (751 × (T
H
/T
L
)) (2)
Table 8. Conversion Times Using Equation 2
Temperature (°C) T
L
(ms) Cycle Time (ms)
–40 53.6 86.5
–30 54.9 87.9
–20 56.4 89.5
–10 58.2 91.6
0 60 93.6
10 61.4 95
20 63.3 97.1
25 64.3 98.2
30 65.6 99.8
40 67.8 102.2
50
70.1
104.7
60 72.5 107.4
70 74.7 109.6
80 77.4 112.6
90 80.4 115.9
100 84.1 120.1
110 87.5 123.8
120 91.2 127.8
130 95.3 132.3
140 99.6 136.9
150 104.5 142.1