TMP05 datasheet(14/28 Pages) AD

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TMP05/TMP06

Rev. 0 | 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 temperature measurement is output when the

OUT line is released by the microcontroller (see Figure 23).

µCONTROLLER PULLS DOWN

OUT LINE HERE

µCONTROLLER RELEASES

OUT LINE HERE

TEMP MEASUREMENT

TIME

Figure 23. 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 24), and,

therefore, 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 VDD to GND, and, therefore, protects the TMP05 from

short-circuit damage.

TMP05

V+

OUT

Ω

Figure 24. TMP05 One Shot Mode OUT Pin Configuration

The advantages of the one shot mode include lower average

power consumption, and the microcontroller knows 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

TH/TL (25°C)

Low

Quarter period

(TH ÷ 4, TL ÷ 4)

10/19 (ms)

Floating

Nominal

40/76 (ms)

High

Double high (TH x 2)

Quarter low (TL ÷ 4)

80/19 (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 × (TH/TL))

(2)

Table 8. Conversion Times Using Equation 2

Temperature (°C)

TL (ms)

Nominal Cycle Time (ms)

–40

65.2

105

–30

66.6

107

–20

68.1

108

–10

69.7

110

71.4

111

73.1

113

74.9

115

75.9

116

76.8

117

78.8

119

121

83.2

123

85.6

126

88.1

128

90.8

131

100

93.6

134

110

96.6

137

120

99.8

140

130

103.2

143

140

106.9

147

150

110.8

151

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