Rainbow-electronics DS2415 Manual do Utilizador descarregar pdf (Página 14)

DS2415

14 of 14

AC ELECTRICAL CHARACTERISTICS

(-40°C to +85°C, V

PUP

= 2.5V to 6.0V, V

BAT

= 2.5V to 5.5V)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Time Slot

SLOT

60 120

Write 1 Low Time

LOW1

115

Write 0 Low Time

LOW0

60 120

Read Low Time

LOWR

115

Read Data Valid

RDV

Release Time

RELEASE

01545

Read Data Setup

Recovery Time

REC

Reset Time High

RSTH

480

Reset Time Low

RSTL

480 960

Presence Detect High

PDH

15 60

Presence Detect Low

PDL

60 240

NOTES:

1. All voltages are referenced to ground.

2. Measured with outputs open.

3. V

PUP

= external pullup voltage.

4. Input load is to ground.

5. An additional reset or communication sequence cannot begin until the reset high time has expired.

6. Read data setup time refers to the time the bus master must pull the I/O line low to read a bit. Data is

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

7. Under certain low voltage conditions V

IL1MAX

may have to be reduced to as much as 0.5V to always

guarantee a Presence Pulse.

8. The reset low time (t

RSTL

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

otherwise, it could mask or conceal interrupt pulses.

9. When V

BAT

ramps up, the oscillator is always off.

10. At V

BAT

= 3V ± 10%

11. At V

BAT

= 5V ± 10%

12. V

IH1

has to be V

BAT

-0.3V or higher.

13. The optimal sampling point for the master is as close as possible to the end time of the 15µs 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 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.

14. The duration of the low pulse sent by the master should be a minimum of 1µs with a maximum value

as short as possible to allow time for the pull-up resistor to recover the line to a high level before the

1-Wire device samples in the case of a Write-One Time or before the master samples in the case of a

Read-One Time.

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