DS18S20-PAR/T&R Maxim Integrated Products, DS18S20-PAR/T&R Datasheet - Page 2

• Manufacturer Part Number: DS18S20-PAR/T&R
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of DS18S20-PAR/T&R

• Full Temp Accuracy: +/- 0.5 C
• Package / Case: TO-92
• Digital Output - Bus Interface: Serial (1-Wire)
• Digital Output - Number Of Bits: 9 bit
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 55 C
• Output Type: Digital
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

DETAILED PIN DESCRIPTIONS Table 1
OVERVIEW
The DS18S20-PAR uses Dallas’ exclusive 1-Wire bus protocol that implements bus communication
using one control signal. The control line requires a weak pullup resistor since all devices are linked to
the bus via a 3-state or open-drain port (the DQ pin in the case of the DS18S20-PAR). In this bus system,
the microprocessor (the master device) identifies and addresses devices on the bus using each device’s
unique 64-bit code. Because each device has a unique code, the number of devices that can be addressed
on one bus is virtually unlimited.
commands and “time slots,” is covered in the 1-WIRE BUS SYSTEM section of this datasheet.
An important feature of the DS18S20-PAR is its ability to operate without an external power supply.
Power is instead supplied through the 1-Wire pullup resistor via the DQ pin when the bus is high. The
high bus signal also charges an internal capacitor (C
bus is low. This method of deriving power from the 1-Wire bus is referred to as “parasite power.”
Figure 1 shows a block diagram of the DS18S20-PAR, and pin descriptions are given in Table 1. The
64-bit ROM stores the device’s unique serial code. The scratchpad memory contains the 2-byte
temperature register that stores the digital output from the temperature sensor. In addition, the scratchpad
provides access to the 1-byte upper and lower alarm trigger registers (T
registers are nonvolatile (EEPROM), so they will retain their data when the device is powered down.
DS18S20-PAR BLOCK DIAGRAM Figure 1
PIN
4.7K
1
2
3
V
GND
PU
DQ
SYMBOL
GND
DQ
NC
PARASITE POWER
Ground.
Data Input/Output pin. Open-drain
to the device when used in parasite power mode (see “Parasite Power” section.)
No Connect. Doesn’t connect to internal circuit.
CIRCUIT
C
PP
INTERNAL V
DD
The 1-Wire bus protocol, including detailed explanations of the
64-BIT ROM
1-wire PORT
AND
2 of 20
PP
), which then supplies power to the device when the
DESCRIPTION
1-Wire
SCRATCHPAD
MEMORY CONTROL
interface pin. Also provides power
LOGIC
H
and T
ALARM HIGH TRIGGER (T
ALARM LOW TRIGGER (T
DS18S20-PAR
TEMPERATURE SENSOR
REGISTER (EEPROM)
REGISTER (EEPROM)
8-BIT CRC GENERATOR
L
). The T
H
and T
L
H
)
)
L