Rainbow Electronics DS2890 - Manual (Page 19)

DS2890
19 of 28
FIGURE 19. INITIALIZATION PROCEDURE “RESET AND PRESENCE
PULSES”
RESISTOR
MASTER
DS2890
MASTER RX "PRESENCE PULSE"
REGULAR SPEED OVERDRIVE SPEED
480 µs £ t
RSTL
<
¥
*
480 µs £ t
RSTH
<
¥
**
15 µs £ t
PDH
< 60 µs
60 £ t
PDL
< 240 µs
48 µs £ t
RSTL
< 80 µs
48 µs £ t
RSTH
<
¥
**
2 µs £ t
PDH
< 6 µs
8 £ t
PDL
< 24 µs
MASTER TX
"RESET PULSE"
V
PULLUP
V
PULLUP MIN
V
IH MIN
V
IL MAX
0V
t
RSTH
t
RSTL
t
PDH
t
PDL
t
R
* In order not to mask interrupt signaling by other devices on the 1-Wire bus and to prevent a power-
on reset of the parasite powered circuit, t
RSTL
+ t
R
should always be less than 960 µs.
** Includes recovery time.
FIGURE 20. READ/WRITE TIMING DIAGRAMS
a) Write-one Time Slot
15µs
(OD: 2µs)
60µs
(OD: 6µs)
DS2890
Sampling Window
V
PULLUP
V
PULLUP MIN
V
IH MIN
V
IL MAX
0V
t
SLOT
t
REC
t
LOW1
REGULAR SPEED OVERDRIVE SPEED
60 µs £ t
SLOT
< 120 µs
1 µs £ t
LOW1
< 15 µs
6 µs £ t
SLOT
< 16 µs
1 µs £ t
LOW1
< 2 µs
1 µs £ t
REC
<
¥
1 µs £ t
REC
<
¥
RESISTOR
MASTER