Rainbow-electronics DS2433 Uživatelský manuál stáhnout pdf (Strana 20)

DS2433

20 of 21

AC ELECTRICAL CHARACTERISTICS

OVERDRIVE SPEED (V

PUP

= 2.8V to 6.0V;-40°C to +85°C)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Time Slot t

SLOT

616

Write 1 Low Time t

LOW1

Write 0 Low Time t

LOW0

616

Read Low Time t

LOWR

Read Data Valid t

RDV

Release Time t

RELEASE

0 1.5 4

Read Data Setup t

Recovery Time t

REC

Reset Time High t

RSTH

Reset Time Low t

RSTL

48 80

Presence Detect High t

PDHIGH

Presence Detect Low t

PDLOW

824

NOTES:

1) All voltages are referenced to ground.

2) V

PUP

= external pullup voltage.

3) Input load is to ground.

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

5) 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 ms of this falling edge.

6) Capacitance on the data pin could be 800pF when power is first applied. If a 5kW resistor is used to

pull up the data line to V

PUP

, 5ms after power has been applied the parasite capacitance will not affect

normal communications.

7) 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.

8) V

is a function of the external pullup resistor and V

PUP

9) Under certain low voltage conditions V

ILMAX

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

guarantee a Presence Pulse.

10) The Copy Scratchpad takes 5ms maximum during which the voltage on the 1-Wire bus must not fall

below 2.8V.

11) During the execution of the Copy Scratchpad command the DS2433 automatically erases the memory

locations to be written to. No extra steps need to be taken by the bus master.

12) The optimal sampling point for the master is as close as possible to the end time of the t

RDV

period

without exceeding t

RDV

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

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