Datasheet TMP05, TMP06 (Analog Devices) - 14

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TMP05/TMP06 Data Sheet One Shot Mode Conversion Rate
In one shot mode, the TMP05/TMP06 output one square wave In continuously converting and one shot modes, the state of the representing temperature when requested by the microcon- CONV/IN pin on power-up determines the rate at which the troller. The microcontroller pulls the OUT pin low and then TMP05/TMP06 measure temperature. The available conversion releases it to indicate to the TMP05/TMP06 that an output is rates are shown in Table 7. required. The time between the OUT pin going low to the time
Table 7. Conversion Rates
it is released should be greater than 20 ns. Internal hysteresis in
CONV/IN Pin Conversion Rate T /T (25°C)
the OUT pin prevents the TMP05/TMP06 from recognizing
H L
Low Quarter period 8.5/16 (ms) that the pulse is going low (if it is less than 20 ns). The (T /4, T /4) temperature measurement is output when the OUT line is H L Floating Nominal 34/65 (ms) released by the microcontrol er (see Figure 22). High Double high (T x 2) 68/16 (ms) H Quarter low (T /4)
µCONTROLLER PULLS DOWN µCONTROLLER RELEASES
L
OUT LINE HERE OUT LINE HERE
The TMP05 (push-pul output) advantage when using the high state conversion rate (double high/quarter low) is lower power
TEMP MEASUREMENT
consumption. However, the trade-off is loss of resolution on the
TH
low time. Depending on the state of the CONV/IN pin, two >
20ns TL
different temperature equations must be used. 019 The temperature equation for the low and floating states’
T0 TIME
03340- conversion rates is Figure 22. TMP05/TMP06 One Shot OUT Pin Signal Temperature (°C) = 421 − (751 × (TH/TL)) (2) In the TMP05 one shot mode only, an internal resistor is
Table 8. Conversion Times Using Equation 2
switched in series with the pul -up MOSFET. The TMP05 OUT
Temperature (°C) T (ms) Cycle Time (ms)
pin has a push-pul output configuration (see Figure 23).
L
–40 53.6 86.5 Therefore, it needs a series resistor to limit the current drawn –30 54.9 87.9 on this pin when the user pul s it low to start a temperature –20 56.4 89.5 conversion. This series resistance prevents any short circuit –10 58.2 91.6 from VDD to GND, and, as a result, protects the TMP05 from 0 60 93.6 short-circuit damage. 10 61.4 95 20 63.3 97.1
V+
25 64.3 98.2 30 65.6 99.8 40 67.8 102.2 50 70.1 104.7
5kΩ
60 72.5 107.4
OUT
70 74.7 109.6 80 77.4 112.6 90 80.4 115.9 016
TMP05
100 84.1 120.1 03340- 110 87.5 123.8 Figure 23. TMP05 One Shot Mode OUT Pin Configuration 120 91.2 127.8 The advantages of the one shot mode include lower average 130 95.3 132.3 power consumption, and the microcontroller knowing that the 140 99.6 136.9 first low-to-high transition occurs after the microcontrol er 150 104.5 142.1 releases the OUT pin. Rev. C | Page 14 of 28 Document Outline Features Applications Functional Block Diagram General Description Product Highlights Revision History Specifications TMP05A/TMP06A Specifications TMP05B/TMP06B Specifications Timing Characteristics Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Theory of Operation Circuit Information Converter Details Functional Description Operating Modes Continuously Converting Mode One Shot Mode Conversion Rate Daisy-Chain Mode TMP05 Output TMP06 Output Application Hints Thermal Response Time Self-Heating Effects Supply Decoupling Layout Considerations Temperature Monitoring Daisy-Chain Application TMP05 Program Code Example 1 Continuously Converting Application TMP05 Program Code Example 2 Outline Dimensions Ordering Guide