DS1923 datasheet(3/52 Pages) DALLAS

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DS1923: Hygrochron Temperature/Humidity Logger iButton with 8kB Data Log Memory

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PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

IO Pin, 1-Wire Write

Standard speed

120

Overdrive speed, VPUP > 4.5V

(Note 11)

Write-0 Low Time

(Note 1)

tW0L

Overdrive speed (Note 11)

7.5

µs

Standard speed

15 -

Write-1 Low Time

(Notes 1, 13)

tW1L

Overdrive speed

1.95 -

µs

IO Pin, 1-Wire Read

Standard speed

15 -

Read Low Time

(Notes 1, 14)

tRL

Overdrive speed

1.95 -

µs

Standard speed

tRL +

Read Sample Time

(Notes 1, 14)

tMSR

Overdrive speed

tRL +

1.95

µs

Real-Time Clock

Accuracy

+25°C

-3

min./

month

Frequency Deviation

-20°C to +85°C

-300

+60

PPM

Temperature Converter

8-bit mode (Note 15)

Conversion Time

tCONV

16-bit mode (11 bits)

240

600

Thermal Response

Time Constant

tRESP

iButton package (Note 16)

130

Conversion Error

Without Software

Correction

(Notes 15, 17, 18, 19)

See Temperature

Accuracy Graphs

°C

Conversion Error With

Software Correction

(Notes 15, 17, 18, 19)

See Temperature

Accuracy Graphs

°C

Humidity Converter (Note 30)

Humidity Response

Time Constant

tRH

Slow moving air (Note 20)

(Note 21)

bits

RH Resolution

0.64

0.04

%RH

RH Range

(Note 22)

100

%RH

RH Accuracy and

Interchangeability

With software correction

(Notes 18, 19, 23, 24, 25)

±5

%RH

RH Nonlinearity

With software correction (Note 18)

RH Hysteresis

(Notes 26, 27)

0.5

%RH

RH Repeatability

(Note 28)

±0.5

%RH

Long-Term Stability

At 50%RH (Note 29)

<1.0

%RH/y

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 does not affect normal communications.

Note 4:

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

Note 5:

Voltage below which, during a falling edge on IO, a logic '0' is detected.

Note 6:

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

Note 7:

Voltage above which, during a rising edge on IO, a logic '1' is detected.

Note 8:

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

Note 9:

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

Note 10:

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

Note 11:

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

Note 12:

Interval during the negative edge on IO 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 13:

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

Note 14:

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

master.

Note 15:

To conserve battery power, use 8-bit temperature logging whenever possible.

Note 16:

This number was derived from a test conducted by Cemagref in Antony, France, in July of 2000.

http://www.cemagref.fr/English/index.htm Test Report No. E42.

DS1923 Datasheet(PDF) 3 Page - Dallas Semiconductor

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