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13

TPL5010-Q1

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SNAS679 – SEPTEMBER 2016

Product Folder Links: TPL5010-Q1

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Copyright © 2016, Texas Instruments Incorporated

Table 4. Most Common Time Intervals Between 1 s to 2 h (continued)

tIP

CALCULATED RESISTANCE (kΩ)

CLOSEST REAL

VALUE (kΩ)

PARALLEL OF TWO 1% TOLERANCE

RESISTORS (kΩ)

50 s

20.047

20.047

28.7 // 66.5

1 min

22.02

22.021

40.2 // 48.7

2 min

29.35

29.349

35.7 // 165.0

3 min

34.73

34.729

63.4 // 76.8

4 min

39.11

39.097

63.4 // 102.0

5 min

42.90

42.887

54.9 // 196.0

6 min

46.29

46.301

75.0 // 121.0

7 min

49.38

49.392

97.6 // 100.0

8 min

52.24

52.224

88.7 // 127.0

9 min

54.92

54.902

86.6 // 150.0

10 min

57.44

57.437

107.0 // 124.0

20 min

77.57

77.579

140.0 // 174.0

30 min

92.43

92.233

182.0 // 187.0

40 min

104.67

104.625

130.0 // 536.00

50 min

115.33

115.331

150.0 // 499.00

1 h

124.91

124.856

221.0 // 287.00

1 h 30 min

149.39

149.398

165.0 // 1580.0

2 h

170.00

170.00

340.0 // 340.0

8.5.4 Quantization Error

The TPL5010-Q1 can generate 1650 discrete timer intervals in the range of 100 ms to 7200 s. The first 9

intervals are multiples of 100 ms. The remaining 1641 intervals cover the range between 1 s to 7200 s. Because

they are discrete intervals, there is a quantization error associated with each value.

The quantization error can be evaluated according to the following formula:

(3)

Where:

(4)

where

•

REXT is the resistance calculated with Equation 1

•

a, b, c are the coefficients of the equation listed in Table 2

(5)

8.5.5 Error Due to Real External Resistance

REXT is a theoretical value and may not be available in standard commercial resistor values. It is possible to

closely approach the theoretical REXT using two or more standard values in parallel. However, standard values

are characterized by a certain tolerance. This tolerance will affect the accuracy of the time interval.

The accuracy can be evaluated using the following procedure:

1. Evaluate the min and max values of REXT (REXT_MIN, REXT_MAX with Equation 1 using the selected commercial

resistance values and their tolerances.

2. Evaluate the time intervals (TADC_MIN[REXT_MIN], TADC_MAX[REXT_MAX]) with Equation 4.

3. Find the errors using Equation 3 with TADC_MIN, TADC_MAX.

The results of the formula indicate the accuracy of the time interval.