INTEGRATED CIRTUIT OF DIGITAL THERMOMETER OF INDUSTRIAL TEMPERATURE RANGE (functional equivalent of DS18B20 "Maxim-Dallas Semiconductor")

Transcription

1 INTEGRATED CIRTUIT OF DIGITAL THERMOMETER OF INDUSTRIAL TEMPERATURE RANGE (functional equivalent of DS18B20 "Maxim-Dallas Semiconductor") The IN18B20D is digital thermometer of industrial temperature range The IC is purposed for temperature measuring and can be used for industrial and analytic measuring in wide range of technological equipment in distributed systems of temperature monitoring and control. Fig. 1 General view of IC in SO case Main features Converts temperature to 12-bit digital code; User-programmable thermometer resolution from 9 to 12 bits; Alarm signal on temperature is outside of programmed limits Each IC has a unique 64-bit serial code not available to change by user; Memory data read/write, data transmitting via 1-wire interface; Battery and data line power supply available; Supply voltage U DD range from 3,0 to 5,5 V; Operating temperature range from minus 55 to plus 125 С; ESD protection up to 2000V; Latch current, min 100 ma at T A = 25 o C. NC NC NC NC V DD NC DQ GND Fig. 2 Pinning Ред.01/

2 Power supply control Interface unit Control unit DQ Internal U DD ADC Temperature sensor GND V DD C pp Power supply supervisor 64 bit EEPROM UID (unique code) RAM Upper threshold temperature (alarm) register TH Lower threshold temperature (alarm) register TL Configuration register CRC code generator Fig. 3 Block diagram Table 1 Package pins and contact pad correspondence and description Pin number Contact pad number Symbol Description 01 - NC Not connected 02 - NC Not connected V DD Power supply pin DQ Data I/O GND Common pin TST Test pin T Test pin THV Test pin 06 - NC Not connected 07 - NC Not connected 08 - NC Not connected 2

3 Table 2 Maximum ratings Symbol Parameter Norm Unit Min Max V DD Supply voltage -0,5 6,0 V Тa Ambient temperature o C Table 3 Recommended operating modes Symbol Parameter Norm Unit Note Min Max V DD Supply voltage V V PU V IL V IH Pullup supply voltage, V 1, 2 capacitive power supply local power supply 3.0 V DD V 1 Low level input voltage at V DD = 5 V V 1, 3 at V DD = 3 V V 1, 2, 3 High level input voltage local power supply 2.2 V DD +0.3 V 1, 4 capacitive power supply 3.0 V DD +0.3 V 1, 2, 4 Тa Operating ambient temperature С - Notes: 1 All voltages are referenced to ground.. 2 For temperature range from minus 55 to plus 100 o C. 3 External driver current 4.0 ma. 4 External driver current 1.0 ma 3

4 Table 4 Electric parameters Parameter, unit, measurement mode Consumption current, μa at 0V V I 0.4 V or V DD 0.3 V V I V DD Dynamic Consumption current, μa at V DD = 5 V Output current, μa at V O = 0.4 V Symbol Targets Min Max I DDS - 1,0 0,9 I ОDD I OL 4,0 4,0 Ambient temperature 25±10 55; 70 25±10-55; 125 Table 5 Reference electric parameters Input current, μa - DQ pin Consumption current, μa Parameter, unit Symbol Measurement mode Temperature measurement drift, С I DQ I DD ΔT Typical value Line driver off, U DD = 5 V 5 0V U I 0,4 V or U DD 0,3 V U I U DD After 1000 hours U DD = 5,5 V 0,75 ±0,2 Ambient temperature 25±10-55; ±10-55; 70 - ±0,5-10; 85 Temperature measurement error, С t ERR - ±2,0-55; 125 * Typical value is arithmetic mean of parameter value, of measured sampling

5 Functional description The IN18B20 uses 1-Wire bus protocol only that implements bus communication using one control signal. The bus is connected to power supply source via pullup resistor since all devices are linked to the bus via a 3-state or open-drain port. In this bus system, the microprocessor (the control 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. Each IN18B20D has unique 64-bit code stored in EEPROM UID. The RAM contains the 2-byte temperature register that stores the temperature value converted to digital format, two 1-byte upper and lower threshold temperature (alarm) registers (TH and TL), and the 1-byte configuration register. The configuration register allows the user to set the resolution of the temperature-to-digital conversion to 9, 10, 11, or 12 bits, that effects on the time of conversion. The TH, TL and configuration registers are nonvolatile (EEPROM), so they will retain data when the device is powered down Another feature of the IN18B20 is the ability to operate without an external power supply. Power is 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 PP ), which then supplies power to the device when the bus is low. This method is referred to as parasite power. Thus the maximum measured temperature is C. An external power supply is required to expand the a range of temperatures up to C Temperature conversion mode The main functionality of the IN18B20 is temperature measuring and A-to-D conversion. The resolution of the temperature measuring is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0,5000; 0,2500; 0,1250 и 0,0625 C respectively. The default resolution is 12-bit. After power-up the IN18B20 stays in idle (non-active) state initially. The master must issue a Convert T [44h] command to initiate a temperature measurement and A- to-d conversion,. After conversion, the resulting thermal data is stored in the 2-byte temperature register of the RAM and the IN18B20 returns to its non-active state. If the IN18B20 is powered by an external supply, the master can control the temperature conversion (after instruction [44h]) under the bus state. The IN18B20 will respond by transmitting 0 (on read time slots issued by master) while the temperature conversion is in progress and 1 when the conversion is done. If the IN18B20 is powered with parasite power, this notification technique is not available since the high level (power supply) must be applied to bus during the entire temperature conversion. At this case device has to control time of the conversion independently. 5

6 Table 6 Instruction set Instruction Code Description Read ROM [33h] Read data from EEPROM UID Match ROM [55h] Match data from EEPROM UID (unique code) Skip ROM [CCh] Skip matching of data from EEPROM UID (unique code) Search ROM [F0h] Search EEPROM UID (unique code) Alarm Search [ECh] Alarm flag search Соnvert T 1) [44h] Initiate a temperature conversion Read Scratchpad [BEh] Read data bytes from RAM and CRC byte Write Scratchpad [4Eh] Write contents of byte 2, 3 and 4 to RAM Copy Scratchpad [48h] Copy RAM content to EEPROM Recall E2 [B8h] Copy data from EEPROM to RAM Read Power Supply [B4h] Report on power supply mode 1) Time to Strong Pullup on after Convert T not exceed 10 μs Memory The IN18B20 s memory is organized as shown in Fig. 4. The memory consists of a main memory (SRAM) and nonvolatile memory (EEPROM). First two registers are registers of temperature converter storage for the high and low alarm trigger registers (TH and TL) followed by upper and lower threshold temperature (alarm) registers (TH and TL), and configuration register. If the IN18B20 alarm function is not implemented, the TH and TL registers can be used as general-purpose memory cells. Byte 0 and byte 1 of the RAM contain the LSB and the MSB of the temperature register, respectively. These bytes are read-only. Bytes 2 and 3 provide access to TH and TL registers. Byte 4 contains the configuration register data. Bytes 5, 6, and 7 are reserved for internal use by the device and cannot be overwritten; these bytes will return all 1 when read. Byte 8 of the RAM is read-only and contains the cyclic redundancy check (CRC) code for bytes 0-7 of the RAM. 6

7 RAM Byte 0 Byte 1 Byte 2 Byte 3 LSB low byte of temperature data (50h) MSB high byte of temperature Data (05h) T H high temperature register data or user «Byte 1» T L low temperature register data or user «Byte 2» EEPROM T H high temperature register data or user «Byte 1» T L low temperature register data or user «Byte 2» Byte 0 Byte 1 Byte 4 Configuration register data Configuration register data Byte 2 Byte 5 Byte 6 Byte 7 Byte 8 Additional data (FFh) Additional data (0Ch) Additional data (10h) CRC data Fig. 4 Memory map Configuration register Byte 4 of the RAM contains the configuration register. The user can set the conversion resolution of the IN18B20 using bits 5 th and 6 th bits (R0 and R1) of the configuration register, as shown in Table 7. The power-up default of these bits is R0 = 1 and R1 = 1 (12-bit resolution). Note that there is a direct regularity between resolution and conversion time. Bit 7 and bits 0 to 4 in the configuration register are reserved for internal use by the device and cannot be overwritten; these bits will return 1 when read. Table 7 R1 R0 Resolution Max Conversion Time bit 93,75 ms (t CONV /8) bit 187,5 ms (t CONV /4) bit 375 ms (t CONV /2) bit 750 ms (t CONV ) 7

8 1-Wire bus protocol The IN18B20 uses a strict 1-Wire communication protocol to insure data integrity. Several signal types are defined by this protocol: reset pulse, presence pulse, write 0, write 1, read 0, and read 1. The master applies all of these signals to bus, with the exception of the presence pulse. Timing parameters of the 1-Wire bus are shown in Table 8. Initialization All communication via 1-Wire bus begins with an initialization sequence. The initialization sequence consists of a reset pulse from the master followed by a presence pulse from the slave devices. The presence pulse indicates to the master that one or few slave devices are on the bus and ready to operate. The initialization timing diagrams is shown in Fig. 5 READ/WRITE time slots The bus master writes data to the IN18B20 during write time slots and reads data from the IN18B20 during read time slots. Time slot is the time interval of the 1-Wire communication protocol. One bit of data is transmitted per time slot. Read/write timing diagrams are shown in fig. 6-8 Table 8 Timing parameters Parameter, unit Temperature conversion time, ms Symbol Min Targets Max 9-bit resolution - 93,75 10-bit resolution - 187,5 11-bit resolution bit resolution Time interval of the 1-Wire communication protocol, μs t CONV t SLOT Write «1» low level duration, μs t LOW Write «0» low level duration, μs t LOW Read data valid, μs t RDV - 15 Recovery time,μs t REC 1 - Reset high level duration, μs t RSTH Reset low level duration, μs t RSTL 1) Note Presence pulse high level duration, μs t PDHIGH Presence pulse low level duration, μs t PDLOW Notes 1. Additional reset or communication sequence cannot start during reset high level. 2.Under with parasite power supply, if t RSTL > 960 μs, a power on reset may occur. 8

9 Driver Т Х «Reset pulse» Driver R Х «Presense pulse» t RSTH U PU U PU MIN U IH MIN U IL MAX 0 V t RSTL t PDH t PDL Resistor Driver IN18B20D 480 μs t RSTL < 480 μs t RSTН < (includes recovery time) 15 μs t PDH < 60 μs 60 μs t PDL < 240 μs Т X transmites R X - receives t RSTL duration has to be less than 960 μs always in order not to mask interruptions issued by another devices on bus. Fig. 5 Initialization timing diagram t SLOT t REC U PU U PU MIN U IH MIN U IL MAX 0 V 15 мкс IN18B20D sampling window 60 мкс t LOW0 Resistor Driver 60 μs t LOWO < t SLOT < 120 μs 1 μs t REC < Fig. 6 Write 0 timing diagram 9

10 t SLOT t REC U PU U PU MIN U IH MIN U IL MAX 0 V t LOW1 15 мкс IN18B20D sampling window 60 мкс Resistor Driver 60 μs t SLOT < 120 μs 1 μs t LOW1 < 15 μs 1 μs t REC < Fig. 7 Write 1 timing diagram t SLOT t REC U PU U PU MIN U IH MIN Driver sampling window U IL MAX 0 V t RDV Resistor Driver IN18B20D 60 μs t SLOT < 120 μs 1 μs t REC < t RDV = 15 μs Fig. 8 Data read timing diagram 10

11 SO- package (MS-012AA) outline drawing D 8 5 E1 H 1 4 hx45 C A1 c e b Mounting plane α L 0,25 (0,010) M C Note Dimensions D, E1 not include the value of fin, which should not exceed 0,25 (0.010) per side. Table 9 mm D E1 H b e α A A1 c L h min max inches min max

12 Contact pad layout Table 10 Contact pad coordinates Contact pad number Coordinates (left bottom corner), mm Contact pad size X Y 01 0,142 0,615 0,090х0, ,742 0,165 0,090х0, ,858 0,166 0,090х0, ,858 1,803 0,090х0, ,858 2,183 0,090х0, ,142 1,554 0,090х0, ,142 1,415 0,090х0, ,142 1,300 0,090х0, ,142 1,185 0,090х0, ,142 1,070 0,090х0,070 Note contact pad size and coordinates are indicated under Passivation layer 12