Serial Bus Digital Switching Characteristics

Unless otherwise noted, these specifications apply for V

LM74-3 MDA.(Note 5). Boldface limits apply for T

noted.

Symbol

Parameter

Conditions

Typical

(Note 6)

Limits

(Note 7)

Units

(Limit)

t

1

SC (Clock) Period

0.16

DC

µs (min)

(max)

t

2

CS Low to SC (Clock) High Set-Up Time

100

ns (min)

t

3

CS Low to Data Out (SO) Delay

70

ns (max)

t

4

SC (Clock) Low to Data Out (SO) Delay

100

ns (max)

t

5

CS High to Data Out (SO) TRI-STATE

200

ns (max)

t

6

SC (Clock) High to Data In (SI) Hold Time

50

ns (min)

t

7

Data In (SI) Set-Up Time to SC (Clock) High

30

ns (min)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond its rated operating conditions.

maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.

Note 3: Human body model, 100 pF discharged through a 1.5 k

Ω resistor. Machine model, 200 pF discharged directly into each pin.

Note 4: The life expectancy of the LM74A will be reduced when operating at elevated temperatures.

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 8: This specification is provided only to indicate how often temperature data is updated. The LM74A can be read at any time without regard to conversion state

(and will yield last conversion result). A conversion in progress will not be interrupted. The output shift register will be updated at the completion of the read and a

new conversion restarted.

Note 9: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy with internal heating. This can cause an error of 0.64˚C at full

rated sink current and saturation voltage based on junction-to-ambient thermal resistance.

Timing Diagrams

20017704

FIGURE 2. Data Output Timing Diagram

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