DS28EA00U+ Maxim Integrated Products, DS28EA00U+ Datasheet - Page 11

• Manufacturer Part Number: DS28EA00U+
• Description: IC THERMOMETER 1-WIRE 8-USOP
• Manufacturer: Maxim Integrated Products

Specifications of DS28EA00U+

• Function: Thermometer, Thermostat
• Topology: Register Bank, Scratchpad
• Sensor Type: Internal
• Sensing Temperature: -40°C ~ 85°C
• Output Type: Digital
• Output Alarm: Yes
• Output Fan: No
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

This command reads the PIO logical status and reports
it together with the state of the PIO output latch in an
endless loop. A PIO Access Read can be terminated at
any time with a 1-Wire reset. PIO Access Read can be
executed in the Chain ON and Chain DONE state.
While the device is in the Chain ON or Chain DONE
state, the PIO output latch states always read out as 1s;
the PIO pin state may not be reported correctly.
The state of both PIO channels is sampled at the same
time. The first sampling occurs during the last (most
significant) bit of the command code F5h. The PIO sta-
tus is then reported to the bus master. While the master
receives the last (most significant) bit of the PIO status
byte, the next sampling occurs and so on until the mas-
ter generates a 1-Wire reset. The sampling occurs with
a delay of t
the previous byte, as shown in Figure 6. The value of
“x” is approximately 0.2µs.
Figure 6. PIO Access Read Timing Diagram
IO
*THE "PREVIOUS BYTE" COULD BE THE COMMAND CODE OR THE DATA BYTE RESULTING FROM THE PREVIOUS PIO SAMPLE.
**THE SAMPLE POINT TIMING ALSO APPLIES TO THE PIO ACCESS WRITE COMMAND, WITH THE "PREVIOUS BYTE" BEING THE WRITE CONFIRMATION BYTE (AAh).
BIT 7
BIT 7
X
REH
+ x from the rising edge of the MS bit of
COMPLEMENT OF B3 TO B0
______________________________________________________________________________________
MOST SIGNIFICANT 2 BITS OF PREVIOUS BYTE*
BIT 6
BIT 6
X
PIO Access Read [F5h]
BIT 5
BIT 5
t
REH
X
1-Wire Digital Thermometer with
+ X
V
TH
SAMPLING POINT**
BIT 4
BIT 4
X
Sequence Detect and PIO
LATCH STATE
PIOB OUTPUT
The PIO Access Write command writes to the PIO out-
put latches, which control the pulldown transistors of
the PIO channels. In an endless loop, this command
first writes new data to the PIO and then reads back the
PIO status. This implicit read-after-write can be used by
the master for status verification. A PIO Access Write
can be terminated at any time with a 1-Wire reset. The
PIO Access Write command is ignored by the device
while in Chain ON or Chain DONE state.
After the command code, the master transmits a PIO
output data byte that determines the new state of the
PIO output transistors. The first (least significant) bit is
associated to PIOA; the next bit affects PIOB. The other
6 bits of the new state byte do not have corresponding
PIO pins. These bits should always be transmitted as 1s.
To switch the output transistor on, the corresponding bit
value is 0. To switch the output transistor off (non-con-
ducting), the bit must be 1. This way the bit transmitted
BIT 3
BIT 3
X
LEAST SIGNIFICANT 2 BITS OF PIO STATUS BYTE
PIO Output Data Bit Assignment
PIOB PIN
STATE
BIT 2
BIT 2
X
PIO Status Bit Assignment
PIO Access Write [A5h]
LATCH STATE
PIOA OUTPUT
BIT 1
BIT 1
PIOB
PIOA PIN
STATE
BIT 0
BIT 0
PIOA
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