DS2784 Maxim Integrated Products, DS2784 Datasheet - Page 36

• Manufacturer Part Number: DS2784
• Description: 1-Cell Stand-Alone Fuel Gauge IC
• Manufacturer: Maxim Integrated Products

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I/O SIGNALING
The 1-Wire bus requires strict signaling protocols to ensure data integrity. The four protocols used by the DS2784
are as follows: the initialization sequence (reset pulse followed by presence pulse), write 0, write 1, and read data.
The bus master initiates all these types of signaling except the presence pulse.
The initialization sequence required to begin any communication with the DS2784 is shown in Figure 13. A
presence pulse following a reset pulse indicates that the DS2784 is ready to accept a net address command. The
bus master transmits (Tx) a reset pulse for t
mode (Rx). The 1-Wire bus line is then pulled high by the pullup resistor. After detecting the rising edge on the DQ
pin, the DS2784 waits for t
Figure 13. 1-Wire Initialization Sequence
WRITE-TIME SLOTS
A write-time slot is initiated when the bus master pulls the 1-Wire bus from a logic-high (inactive) level to a logic-low
level. There are two types of write-time slots: write 1 and write 0. All write-time slots must be t
1μs minimum recovery time, t
t
write 0 occurs. The sample window is illustrated in Figure 14. For the bus master to generate a write-1 time slot, the
bus line must be pulled low and then released, allowing the line to be pulled high less than t
write time slot. For the host to generate a write 0 time slot, the bus line must be pulled low and held low for the
duration of the write-time slot.
READ-TIME SLOTS
A read-time slot is initiated when the bus master pulls the 1-Wire bus line from a logic-high level to a logic-low level.
The bus master must keep the bus line low for at least 1μs and then release it to allow the DS2784 to present valid
data. The bus master can then sample the data t
slot, the DS2784 releases the bus line and allows it to be pulled high by the external pullup resistor. All read-time
slots must be t
timing specifications in the Electrical Characteristics table for more information.
LOW0_MIN
DQ
after the line falls. If the line is high when sampled, a write 1 occurs. If the line is low when sampled, a
SLOT
LINE TYPE LEGEND:
in duration with a 1μs minimum recovery time, t
PDH
DS2784: 1-Cell Stand-Alone Fuel Gauge IC with Li+ Protector and SHA-1 Authentication
t
REC
RSTL
BUS MASTER ACTIVE LOW
BOTH BUS MASTER AND
DS2784 ACTIVE LOW
and then transmits the presence pulse for t
, between cycles. The DS2784 samples the 1-Wire bus line between t
t
PDH
RSTL
RDV
. The bus master then releases the line and goes into Receive
from the start of the read-time slot. By the end of the read-time
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t
PDL
DS2784 ACTIVE LOW
RESISTOR PULLUP
REC
t
RSTH
PDL
, between cycles. See Figure 14 and the
.
RDV
SLOT
after the start of the
in duration with a
PACK+
PACK-
LOW1_MAX
and