DS1822+ Maxim Integrated Products, DS1822+ Datasheet - Page 16

• Manufacturer Part Number: DS1822+
• Description: Board Mount Temperature Sensors IC THERMOMETER ECONO DIG
• Manufacturer: Maxim Integrated Products

Specifications of DS1822+

• Temperature Threshold: Programmable
• Full Temp Accuracy: +/- 2 C
• Package / Case: TO-92
• Digital Output - Bus Interface: 1-Wire
• Digital Output - Number Of Bits: 9 bit to 12 bit
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 3 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Output Type: Digital
• Supply Current: 1.5 mA
• Ic Output Type: Digital
• Sensing Accuracy Range: ± 2°C
• Supply Voltage Range: 3V To 5.5V
• Resolution (bits): 12bit
• Sensor Case Style: TO-92
• No. Of Pins: 3
• Accuracy %: 2°C
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The DS1822 samples the 1-Wire bus during a window that lasts from 15μs to 60μs after the master
initiates the write time slot. If the bus is high during the sampling window, a 1 is written to the DS1822.
If the line is low, a 0 is written to the DS1822.
READ/WRITE TIME SLOT TIMING DIAGRAM Figure 14
READ TIME SLOTS
The DS1822 can only transmit data to the master when the master issues read time slots. Therefore, the
master must generate read time slots immediately after issuing a Read Scratchpad [BEh] or Read Power
Supply [B4h] command, so that the DS1822 can provide the requested data. In addition, the master can
generate read time slots after issuing Convert T [44h] or Recall E
of the operation as explained in the DS1822 FUNCTION COMMAND section.
All read time slots must be a minimum of 60μs in duration with a minimum of a 1μs recovery time
between slots. A read time slot is initiated by the master device pulling the 1-Wire bus low for a
minimum of 1μs and then releasing the bus (see Figure 14). After the master initiates the read time slot,
the DS1822 will begin transmitting a 1 or 0 on bus. The DS1822 transmits a 1 by leaving the bus high
and transmits a 0 by pulling the bus low. When transmitting a 0, the DS1822 will release the bus by the
end of the time slot, and the bus will be pulled back to its high idle state by the pullup resister. Output
1-WIRE BUS
1-WIRE BUS
V
GND
V
GND
PU
PU
> 1μs
OF SLOT
START
15μs
15μs
MASTER WRITE “0” SLOT
MASTER READ “0” SLOT
LINE TYPE LEGEND
60μs < T
MIN
Master samples
15μs
Bus master pulling low
Resistor pullup
DS1822 Samples
TYP
X
“0” < 120μs
45μs
MAX
30μs
16 of 21
> 1 μs
OF SLOT
START
15μs
DS1822 pulling low
15μs
1μs < T
1μs < T
2
[B8h] commands to find out the status
MASTER WRITE “1” SLOT
> 1μs
MASTER READ “1” SLOT
REC
REC
MIN
<
<
∞
∞
Master samples
15μs
DS1822 Samples
TYP
MAX
30μs
DS1822