Rainbow-electronics DS1920 Manual de usuario descargar pdf (Pagina 21)

DS1920

21 of 22

AC ELECTRICAL CHARACTERISTICS:

1-WIRE INTERFACE (-55°C to +100°C; V

PUP

=2.8V to 6.0V)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Time Slot t

SLOT

60 120

µs

Write 1 Low Time t

LOW1

1 15

µs

Write 0 Low Time t

LOW0

60 120

µs

Read Data Valid t

RDV

exactly 15

µs

Release Time t

RELEASE

0 15 45

µs

Read Data Setup t

µs

Recovery Time t

REC

µs

Reset Time High t

RSTH

480

µs

Reset Time Low t

RSTL

480 4800

µs

6,7

Presence Detect High t

PDHIGH

15 60

µs

Presence Detect Low t

PDLOW

60 240

µs

NOTES:

1. Temperature conversion will work with ±2°C accuracy down to V

PUP

= 3.4V.

2. All voltages are referenced to ground.

3. I

specified with low impedance pull up to 5.0V.

4. Active current refers to temperature conversion.

5. Writing to EEPROM consumes approximately 200 µA.

6. t

RSTL

may be up to 4800 µs. With longer times, the result of temperature conversion may get lost.

7. The reset low time should be restricted to a maximum of 960 ms, to allow interrupt signaling,

otherwise it could mask or conceal interrupt pulses.

8. 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 and will remain valid for 14 µs minimum. (15

µs total from falling edge on 1-Wire bus.)

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

to pull up the data line to V

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

affect normal communications.

10. Under certain low voltage conditions V

ILMAX

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

guarantee a presence pulse.

11. See Typical Curve for specification limits outside the 0°C to 70°C range. Thermometer error reflects

sensor accuracy as tested during calibration.

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