Rainbow-electronics DS2432 Manual do Utilizador descarregar pdf (Página 30)

PRELIMINARY DS2432

30 of 30

AC ELECTRICAL CHARACTERISTICS

OVERDRIVE SPEED (V

PUP

=2.8V to 5.25V; -40°C to +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

2µs10

Release Time t

RELEASE

0 1.5 4 µs

Read Data Setup t

1µs4

Recovery Time t

REC

1µs

Reset High Time t

RSTH

48 µs

Reset Low Time t

RSTL

48 80 µs

Presence Detect High t

PDHIGH

26µs

Presence Detect Low t

PDLOW

824µs

Programming Time t

PROG

10 ms

SHA Computation Time t

CSHA

1.0 2.0 ms 9

NOTES:

1. All voltages are referenced to ground.

2. V

PUP

= external pull-up voltage.

3. Input load is to ground.

4. 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.

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

pull up the data line to V

PUP

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

normal communications.

6. 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.

7. V

is a function of the external pull-up resistor and V

PUP

8. Under certain low voltage conditions V

ILMAX

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

guarantee a Presence Pulse. V

is a function of V

PUP

and the reset low time.

9. During write operations to the EEPROM and during the computation of Message Authentication

Codes (MAC) the voltage on the 1-Wire bus must not fall below 2.8V. The computation of a MAC

takes maximum 2.0 ms. Copying scratchpad data to the EEPROM takes max. 10 ms.

10. 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

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 releases the line (t

RELEASE

= 0).

1 2 ... 25 26 27 28 29 30

Comentários a estes Manuais

Sem comentários

Rainbow-electronics DS2432 Manual do Utilizador Página 30

Comentários a estes Manuais

Manuais e produtos relacionados com Painel de controlo Rainbow-electronics DS2432