Rainbow-electronics DS2890 Manual de usuario descargar pdf (Pagina 27)

DS2890

27 of 28

AC ELECTRICAL CHARACTERISTICS - REGULAR 1-WIRE SPEED

2.8V £ V

PUP

£ 6.0V, -40°C £ T

£ +85°C

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Time Slot t

SLOT

60 120 µs

Write 1 Low Time t

LOW1

115µs

Write 0 Low Time t

LOW0

60 120 µs

Read Low Time t

LOWR

115µs

Read Data Valid t

RDV

15 µs 1

Release Time t

RELEASE

01545µs

Read Data Setup t

1µs2

Recovery Time t

REC

1µs

Reset High Time t

RSTH

480 µs 3

Reset Low Time t

RSTL

480 µs 4

Presence Detect High t

PDH

15 60 µs

Presence Detect Low t

PDL

60 240 µs

Notes:

1. The optimal sampling point for the master is as close as possible to the end time of the 15 ms t

RDV

period without exceeding t

RDV

. For the case of a Read-one time slot, this maximizes the amount of

time for the pull-up resistor to recover the line to a high level. For a Read-zero time slot it ensures

that a read will occur before the fastest 1-Wire device(s) release the line (t

RELEASE

= 0).

Read data setup time refers to the time the host must pull the 1-Wire bus low to read a bit. Data is

guaranteed to be valid within 1 µs of this falling edge.

An additional reset or communication sequence cannot begin until the reset high time (t

RSTH

) has

expired.

The reset low time (t

RSTL

) should be restricted to a maximum of 960 µs, to allow interrupt signaling,

otherwise, it could mask or conceal interrupt pulses.

AC ELECTRICAL CHARACTERISTICS - OVERDRIVE 1-WIRE SPEED

2.8V £ V

PUP

£ 6.0V, -40°C £ T

£ +85°C

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Time Slot t

SLOT

616µs

Write 1 Low Time t

LOW1

12µs

Write 0 Low Time t

LOW0

616µs

Read Low Time t

LOWR

12µs

Read Data Valid t

RDV

2µs1

Release Time t

RELEASE

01.54 µs

Read Data Setup t

1µs4

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Rainbow-electronics DS2890 Manual de usuario Pagina 27

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