Rainbow Electronics DS1775R_T - Manual (Page 12)

DS1775
12 of 13
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
100 KHZ
Bus free time between a
STOP and START
condition t
BUF
Fast Mode
Standard Mode
1.3
4.7 µs
Hold time (repeated)
START condition t
HD:STA
Fast Mode
Standard Mode
0.6
4.0 µs 5
LOW period of SCL t
LOW
Fast Mode
Standard Mode
1.3
4.7 µs
HIGH period of SCL t
HIGH
Fast Mode
Standard Mode
0.6
4.0 µs
Set-up time for a
repeated START t
SU:STA
Fast Mode
Standard Mode
0.6
4.7 µs
Data hold time t
HD:DAT
Fast Mode
Standard Mode
0
0 0.9
0.9 µs 6
Data set-up time t
SU:DAT
Fast Mode
Standard Mode
100
250 ns 7
Rise time of both SDA and
SCL signals t
R
Fast Mode
Standard Mode
20+
0.1C
B
300
1000
ns 8
Fall time of both SDA and
SCL signals t
F
Fast Mode
Standard Mode
20+
0.1C
B
300
300 ns 8
Set-up time for STOP t
SU:STO
Fast Mode
Standard Mode
0.6
4.0 µs
Capacitive load for each bus
line C
b
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
≥ 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, (972) 371-4448, for operation requiring temperature readings greater
than 120°C.