DS2480 Dallas Semiconducotr, DS2480 Datasheet - Page 15

• Manufacturer Part Number: DS2480
• Description: Serial 1.Wire Line Driver
• Manufacturer: Dallas Semiconducotr

PULSE WAVE FORMS, DISARMED
The pulse command can be used to generate a strong
pull–up to 5V and a 12V programming pulse, respec-
tively. The duration of the pulse is predefined if the
parameter value code of parameter 010 (Programming
Pulse Duration) and parameter 011 (Strong Pull–Up
Duration), has a value from 000 to 110 (see Table 4).
Figures 7a and 7b show the timing of a pulse with prede-
STRONG PULL–UP TO 5V, PREDEFINED DURATION Figure 7a
The processing of a pulse command is essentially the
same, regardless if a strong pull–up or a programming
pulse is requested. At t
pulse command byte. At t
command and immediately generates the pulse. The
pulse ends at t
mand response byte to inform the host that the com-
12V PROGRAMMING PULSE, PREDEFINED DURATION Figure 7b
A correct programming pulse can only be generated if
the 12V programming voltage is available at the Vpp pin
of the DS2480. The slew rate of the rising and falling
edge of the programming pulse (“steep slopes”) is not
actively controlled by DS2480.
12V
5V
0V
5V
0V
END OF PREVIOUS
END OF PREVIOUS
TIME SLOT
TIME SLOT
3
and the DS2480 sends out the com-
1
2
the DS2480 has received the
the host starts sending the
t
1
t
1
TIME
IDLE
TIME
IDLE
t
2
t
2
STEEP SLOPES
t
SPU
t
PP
fined duration, which should be considered the normal
case. If an infinite duration is chosen (parameter value
code 111), the host must terminate the pulse command,
as shown in Figures 7c and 7d. All versions of Figure 7
assume that bit 1 of the pulse command is 0, i.e., dis-
armed mode. See section Communication Commands,
Pulse, for more details on possibilities of the pulse
command.
mand is completed. The idle time between t
determined by the time to transmit the command byte at
the selected baud rate. The idle time between t
comprised of the time to transmit the response byte,
plus the response time of the host plus the time to trans-
mit the command and/or data to generate the next time
slot.
For EPROM programming, only a single slave device
should be connected to the 1–Wire bus and the cable
must to be short, not to exceed a few meters. One
should not attempt generating a programming pulse
with a non–EPROM device on the bus; this may dam-
age the device as well as the DS2480.
t
t
3
3
TIME
IDLE
IDLE
TIME
t
4
t
4
BEGIN OF NEXT
BEGIN OF NEXT
TIME SLOT
TIME SLOT
042498 15/26
1
3
and t
and t
DS2480
2
4
is
is