DS2422 datasheet(4/48 Pages) DALLAS

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DS2422

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Note 1:

System Requirement

Note 2:

Maximum allowable pullup resistance is a function of the number of 1-Wire devices in the system and 1-Wire recovery times. The

specified value here applies to systems with only one device and with the minimum 1-Wire recovery times. For more heavily

loaded systems, an active pullup such as that found in the DS2480B may be required.

Note 3:

Capacitance on the data pin could be 800pF when VPUP is first applied. If a 2.2k

W resistor is used to pull up the data line, 2.5µs

after VPUP has been applied the parasite capacitance will not affect normal communications.

Note 4:

Guaranteed by design, not production tested.

Note 5:

VTL, VTH are a function of the internal supply voltage.

Note 6:

Voltage below which, during a falling edge on I/O, a logic '0' is detected.

Note 7:

The voltage on I/O needs to be less or equal to VILMAX whenever the master drives the line low.

Note 8:

Voltage above which, during a rising edge on I/O, a logic '1' is detected.

Note 9:

After VTH is crossed during a rising edge on I/O, the voltage on I/O has to drop by VHY to be detected as logic '0'.

Note 10:

The I-V characteristic is linear for voltages less than 1V.

Note 11:

The earliest recognition of a negative edge is possible at tREH after VTH has been previously reached.

Note 12:

Highlighted numbers are NOT in compliance with the published iButton standards. See comparison table below.

Note 13:

Interval during the negative edge on I/O at the beginning of a Presence Detect pulse between the time at which the voltage is

90% of VPUP and the time at which the voltage is 10% of VPUP.

Note 14:

e represents the time required for the pullup circuitry to pull the voltage on I/O up from VIL to VTH.

Note 15:

d represents the time required for the pullup circuitry to pull the voltage on I/O up from VIL to the input high threshold of the bus

master.

Note 16:

This is the expected range when using a crystal equivalent to the KDS SN14J (12.5pF).

Note 17:

Time to reach 63% of the temperature change; measured at a temperature transition step from +25°C to +85°C.

Note 18:

A 2-point calibration trim at 3V must be done to achieve the specified accuracy at 3V. An application note is available to help

developers perform the calibration by writing the trim registers to properly orient the error curve.

Note 19:

The duration is user-programmable from 0ms (code 00h) to 127.5ms (code FFh) with a tolerance of ±0.5ms. See Delay Register,

address 400h, for details.

STANDARD VALUES

DS2422 VALUES

PARAMETER

STANDARD SPEED

OVERDRIVE SPEED

STANDARD SPEED

OVERDRIVE SPEED

NAME

MIN

MAX

MIN

MAX

MIN

MAX

MIN

MAX

tSLOT (incl. tREC)

61µs

(undef.)

7µs

(undef.)

65µs

(undef.)

9.5µs

(undef.)

tRSTL

480µs

(undef.)

48µs

80µs

690µs

720µs

70µs

80µs

tPDH

15µs

60µs

2µs

6µs

15µs

63.5µs

2µs

7µs

tPDL

60µs

240µs

8µs

24µs

60µs

287µs

7µs

28µs

tW0L

60µs

120µs

6µs

16µs

60µs

120µs

7.5µs

12µs

1) Intentional change, longer recovery time requirement due to modified 1-Wire front end.

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