DS1482 Datasheet, PDF (3/7 Pages) Dallas Semiconductor – 1-Wire Level Shifter and Line Driver with Load Sensor

Figure 2. Typical Operating Circuit
VCC = 5V
RS
VCCQ = 3.3V
IRLMS6702
(21) VCCQ
SH7622
µC
(164) TxD0
(171) RxD0
(32) PTA0
(31) PTA1
(178) IRQ7
VCC
PCTLZ
VCCQ
DS1482
TXD
I/O
RXD
SPU
START
DONE
GND
1-Wire
NETWORK
DS1482
Selecting RS
Assuming that the series resistance of the FET in
on-condition can be neglected, the value of RS is
limited as follows:
RSmax = 0.0015 x VCCmin/I(standby,max)
RSmin = 0.01 x VCCmax/I(active,min)
Example:
VCCmin = 4.5V, VCCmax = 5.5V
I(standby,max) = 0.15mA
I(active,min) = 12mA
RSmax = 45W, RSmin = 4.58W
To maximize available power on the 1-Wire line,
RS should be close to the lowest permissible
value, in this example 5.1W ±5%. The effect of the
on-chip pullup resistor is negligible.
Figure 3. DS1482 Application Signals, Normal Communication
TXD
H
L
I/O
H
L
RXD
H
L
SPU, START, DONE ALL LOW
Figure 4. DS1482 Application Signals, Strong Pullup Case
TXD
H
L
I/O
H
L
RXD
H
L
SPU
H
L
PCTLZ
H
L
1
CURRENT
23
t_CF
DONE
H
L
START
4
H
L
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