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PDF DS1624 Data sheet ( Hoja de datos )
| Número de pieza | DS1624 | |
| Descripción | Digital Thermometer and Memory | |
| Fabricantes | Dallas | |
| Logotipo |  |
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DS1624
Digital Thermometer and Memory
FEATURES
§ Temperature measurements require no
external components
§ Measures temperatures from -55°C to +125°C
in 0.03125°C increments. Fahrenheit
equivalent is -67°F to +257°F in 0.05625°F
increments
§ Temperature is read as a 13-bit value (two
byte transfer)
§ Converts temperature to digital word in 1
second (max)
§ 256 bytes of E2 memory on board for storing
information such as frequency compensation
coefficients
§ Data is read from/written via a 2-wire serial
interface (open drain I/O lines)
§ Applications include temperature-
compensated crystal oscillators for test
equipment and radio systems
§ 8-pin DIP or SOIC packages
PIN ASSIGNMENT
SDA
SCL
NC
GND
1
2
3
4
8 VDD
7 A0
6 A1
5 A2
DS1624S 8-PIN SOIC (208 MIL)
See Mech Drawings Section
SDA
SCL
NC
GND
1
2
3
4
8 VDD
7 A0
6 A1
5 A2
DS1624 8-PIN DIP (300 MIL)
See Mech Drawings Section
PIN DESCRIPTION
SDA - 2-Wire Serial Data Input/Output
SCL - 2-Wire Serial Clock
GND - Ground
A0 - Chip Address Input
A1 - Chip Address Input
A2 - Chip Address Input
VDD - Digital Power Supply (+3V - +5V)
NC - No Connection
DESCRIPTION
The DS1624 consists of a digital thermometer and 256 bytes of E2 memory. The thermometer provides
13-bit temperature readings which indicate the temperature of the device. The E2 memory allows a user to
store frequency compensation coefficients for digital correction of crystal frequency due to temperature.
Any other type of information may also reside in this user space.
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1 page  
DS1624
three least significant bits of the slave address. The last bit of the control byte (R/ W ) defines the
operation to be performed. When set to a “1”, a read operation is selected, when set to a “0”, a write
operation is selected. Following the START condition the DS1624 monitors the SDA bus checking the
device type identifier being transmitted. Upon receiving the 1001 code and appropriate device select bits,
the slave device outputs an acknowledge signal on the SDA line.
2-WIRE SERIAL COMMUNICATION WITH DS1624 Figure 3
OPERATION-MEASURING TEMPERATURE
A block diagram of the DS1624 is shown in Figure 1. The DS1624 measures temperatures through the
use of an on–board proprietary temperature measurement technique. A block diagram of the temperature
measurement circuitry is shown in Figure 4.
The DS1624 measures temperature by counting the number of clock cycles that an oscillator with a low
temperature coefficient goes through during a gate period determined by a high temperature coefficient
oscillator. The counter is preset with a base count that corresponds to –55°C. If the counter reaches zero
before the gate period is over the temperature register, which is also preset to the –55 °C value, is
incremented indicating that the temperature is higher than –55 °C.
At the same time, the counter is preset with a value determined by the slope accumulator circuitry. This
circuitry is needed to compensate for the parabolic behavior of the oscillators over temperature. The
counter is then clocked again until it reaches zero. If the gate period is still not finished, then this process
repeats.
The slope accumulator is used to compensate for the nonlinear behavior of the oscillators over
temperature, yielding a high resolution temperature measurement. This is done by changing the number
of counts necessary for the counter to go through for each incremental degree in temperature. To obtain
the desired resolution, both the value of the counter and the number of counts per °C (the value of the
slope accumulator) at a given temperature must be known.
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5 Page 
BUS MASTER
MODE
TX
DS1624
MODE
RX
DATA (MSB
FIRST)
NACK
TX RX STOP
{Command protocol for writing to EEPROM}
{Start here}
TX RX START
TX RX <cadr,0>
COMMENTS
Bus Master sends “NO
ACKNOWLEDGE” bit.
Bus Master initiates the STOP condition.
Bus Master initiates a Start condition.
Bus Master sends DS1624 address;
R/ W =0;
RX
TX
ACK
DS1624 generates acknowledge bit.
TX RX 17h Bus Master sends Access Memory
command protocol.
RX
TX
ACK
DS1624 generates acknowledge bit.
TX RX <madr> Bus Master sets the starting memory
address.
RX
TX
ACK
DS1624 generates acknowledge bit.
TX
RX
<data>
Bus Master sends the first byte of data.
RX
TX
ACK
DS1624 generates acknowledge bit.
TX
RX
<data>
Bus Master sends the second byte of data.
RX
TX
ACK
DS1624 generates acknowledge bit.
. . ..
. . ..
. . ..
. . ..
TX
RX
<data>
Bus Master sends the n-th byte of data.
RX
TX
ACK
DS1624 generates acknowledge bit.
TX
RX
STOP
Bus Master initiates the STOP condition.
{Command protocol for reading from EEPROM}
{Start here}
TX RX START Bus Master initiates a Start condition.
TX RX <cadr,0> Bus Master sends DS1624 address;
R/ W =0;
RX
TX
ACK
DS1624 generates acknowledge bit.
TX RX 17h Bus Master sends Access Memory
command protocol.
RX
TX
ACK
DS1624 generates acknowledge bit.
TX RX <madr> Bus Master sends the starting memory
address.
RX
TX
ACK
DS1624 generates acknowledge bit.
TX RX START Bus Master initiates a Repeated Start
condition.
TX RX <cadr,1> Bus Master sends DS1624 address;
R/ W =1;
RX
TX
ACK
DS1624 generates acknowledge bit.
RX
TX
<data>
DS1624 sends the first byte of data.
TX
RX
ACK
Bus Master generates acknowledge bit.
DS1624
NOTES
1
3
2, 4
1
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11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet DS1624.PDF ] | |
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