DS1775_02 Datasheet, PDF (13/14 Pages) Dallas Semiconductor – SOT23-5 Digital Thermometer and Thermostat

DS1775
AC ELECTRICAL CHARACTERISTICS:
2–WIRE INTERFACE
(–55°C to +125°C; V_DD =2.7V to 5.5V)
PARAMETER
SYMBOL CONDITION MIN TYP MAX UNITS NOTES
SCL clock frequency
f_SCL
Fast Mode
Standard Mode
400 KHZ
100
Bus free time between a
t_BUF
Fast Mode 1.3
ms
STOP and START
Standard Mode 4.7
condition
Hold time (repeated)
START condition
t_HD:STA
Fast Mode 0.6
Standard Mode 4.0
ms
5
LOW period of SCL
t_LOW
Fast Mode 1.3
ms
Standard Mode 4.7
HIGH period of SCL
t_HIGH
Fast Mode 0.6
ms
Standard Mode 4.0
Set-up time for a
t_SU:STA
Fast Mode 0.6
ms
repeated START
Standard Mode 4.7
Data hold time
t_HD:DAT
Fast Mode
0
Standard Mode 0
0.9
ms
6
0.9
Data set-up time
t_SU:DAT
Fast Mode 100
Standard Mode 250
ns
7
Rise time of both SDA and
SCL signals
Fall time of both SDA and
SCL signals
Set-up time for STOP
t_R
t_F
t_SU:STO
Fast Mode
Standard Mode
Fast Mode
Standard Mode
Fast Mode
Standard Mode
20+
0.1C_B
20+
0.1C_B
0.6
4.0
300
ns
8
1000
300
ns
8
300
ms
Capacitive load for each bus
C_b
line
400
pF
8
Input Capacitance
C_I
5
pF
NOTES:
1. All voltages are referenced to ground.
2. I/O pins of fast mode devices must not obstruct the SDA and SCL lines if V_DD is switched off.
3. I_DD specified with O.S. pin open.
4. I_DD specified with V_DD at 5.0V and SDA, SCL = 5.0V, 0°C to +70°C.
5. After this period, the first clock pulse is generated.
6. The maximum t_HD:DAT has only to be met if the device does not stretch the LOW period (t_LOW ) of the
SCL signal.
7. A fast mode device can be used in a standard mode system, but the requirement t_SU:DAT ³ 250 ns must
then be met. This will automatically be the case if the device does not stretch the LOW period of the
SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next
data bit to the SDA line t_{R MAX} +t_SU:DAT = 1000+250 = 1250 ns before the SCL line is released.
8. C_b – total capacitance of one bus line in pF.
9. Internal heating caused by O.S. loading will cause the DS1775 to read approximately 0.5ºC higher if
O.S. is sinking the max rated current.
10. Contact the factory in Dallas, [phone], for operation requiring temperature readings greater
than 120°C.
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