Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsDS28EA00U+

General Description

The DS28EA00 is a digital thermometer with 9-bit (0.5°C)

to 12-bit (1/16°C) resolution and alarm function with non-

volatile (NV), user-programmable upper and lower trigger

points. Each DS28EA00 has its own unique 64-bit regis-

tration number that is factory programmed into the chip.

Data is transferred serially through the 1-Wire

protocol,

which requires only one data line and a ground reference

for communication. The improved 1-Wire front-end with

hysteresis and glitch filter enables the DS28EA00 to per-

form reliably in large 1-Wire networks. Unlike other 1-Wire

thermometers, the DS28EA00 has two additional pins to

implement a sequence-detect function. This feature

allows the user to discover the registration numbers

according to the physical device location in a chain, e.g.,

to measure the temperature in a storage tower at different

height. If the sequence-detect function is not needed,

these pins can be used as general-purpose input or out-

put. The DS28EA00 can derive the power for its operation

directly from the data line (“parasite power”), eliminating

the need for an external power supply.

Applications

Data Communication Equipment

Process Temperature Monitoring

HVAC Systems

Features

♦ Digital Thermometer Measures Temperatures

from -40°C to +85°C

♦ Thermometer Resolution is User Selectable from

9 to 12 Bits

♦ Unique 1-Wire Interface Requires Only One Port

Pin for Communication

♦ Each Device Has a Unique 64-Bit, Factory-

Lasered Registration Number

♦ Multidrop Capability Simplifies Distributed

Temperature-Sensing Applications

♦ Improved 1-Wire Interface with Hysteresis and

Glitch Filter

♦ User-Definable NV Alarm Threshold Settings/User

Bytes

♦ Alarm Search Command to Quickly Identify

Devices Whose Temperature is Outside of

Programmed Limits

♦ Standard and Overdrive 1-Wire Speed

♦ Two General-Purpose Programmable IO (PIO) Pins

♦ Chain Function Sharing the PIO Pins to Detect

Physical Sequence of Devices in Network

♦ Operating Range: +3.0V to +5.5V, -40°C to +85°C

♦ Can Be Powered from Data Line

♦ 8-Pin µSOP Package

DS28EA00

1-Wire Digital Thermometer with

Sequence Detect and PIO

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

Ordering Information

DS28EA00

PIOB PIOA

GND

NOTE: SCHEMATIC SHOWS PIO PINS WIRED FOR SEQUENCE-DETECT FUNCTION.

1-Wire

MASTER

DS28EA00

PIOB

PX. Y

MICROCONTROLLER

PIOA

GND

DS28EA00

PIOB PIOA

GND

Typical Operating Circuit

Rev 2; 4/09

PART TEMP RANGE PIN-PACKAGE

DS28EA00U+ -40°C to +85° C 8 μSOP

DS28EA00U+T&R -40°C to +85°C 8 μSOP

Pin Configuration appears at end of data sheet.

Denotes a lead(Pb)-free/RoHS-compliant package.

T&R = Tape and reel.

1-Wire is a registered trademark of Maxim Integrated Products, Inc.

Summary of content (29 pages)

PAGE 1
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO General Description The DS28EA00 is a digital thermometer with 9-bit (0.5°C) to 12-bit (1/16°C) resolution and alarm function with nonvolatile (NV), user-programmable upper and lower trigger points. Each DS28EA00 has its own unique 64-bit registration number that is factory programmed into the chip. Data is transferred serially through the 1-Wire® protocol, which requires only one data line and a ground reference for communication.
PAGE 2
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO ABSOLUTE MAXIMUM RATINGS IO Voltage Range to GND ........................................-0.5V to +6V IO Sink Current....................................................................20mA Maximum PIOA or PIOB Pin Current...................................20mA Maximum Current Through GND Pin ..................................40mA Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................
PAGE 3
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO ELECTRICAL CHARACTERISTICS (continued) (TA = -40°C to +85°C.) (Note 1) PARAMETER SYMBOL Presence-Detect High Time t PDH Presence-Detect Fall Time (Notes 3, 15) tFPD Presence-Detect Low Time t PDL Presence-Detect Sample Time (Notes 2, 16) tMSP CONDITIONS MIN TYP MAX Standard speed 15 60 Overdrive speed 2 6 Standard speed 1.125 8.1 Overdrive speed 0 1.
PAGE 4
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO ELECTRICAL CHARACTERISTICS (continued) (TA = -40°C to +85°C.) (Note 1) Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: Note 10: Note 11: Note 12: Note 13: Note 14: Note 15: Note 16: Note 17: Note 18: Note 19: Note 20: Note 21: Note 22: Note 23: Note 24: Note 25: Note 26: Note 27: 4 Specifications at TA = -40°C are guaranteed by design and not production tested. System requirement.
PAGE 5
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Pin Description PIN NAME 1 IO FUNCTION 1-Wire Bus Interface and Parasitic Power Supply. Open-drain pin that requires external pullup resistor. 2, 3, 5 N.C. No Connection 4 GND Ground Supply 6 Open-Drain PIOA Channel and Chain Output. For sequence detection, PIOA must be connected to PIOA (DONE) PIOB of the next device in the chain; leave open or connect to GND for the last device in the chain.
PAGE 6
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Block Diagram INTERNAL VDD DS28EA00 POWER-SUPPLY SENSOR VDD (ON) 1-Wire ROM FUNCTION CONTROL IO RCO 64-BIT REGISTRATION NUMBER PIOB (EN) PIOA (DONE) DEVICE FUNCTION CONTROL 8-BIT CRC GENERATOR ALARM AND CONFIGURATION REGISTERS 64-BIT SCRATCHPAD TEMPERATURE SENSOR DS28EA00 COMMAND LEVEL: AVAILABLE COMMANDS: DATA FIELD AFFECTED: 1-Wire ROM FUNCTION COMMANDS (SEE FIGURE 11) READ ROM MATCH ROM SEARCH ROM CONDITIONAL SEARCH ROM COND
PAGE 7
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO MSB LSB 8-BIT CRC CODE 8-BIT FAMILY CODE (42h) 48-BIT SERIAL NUMBER MSB LSB LSB MSB LSB MSB Figure 2. 64-Bit Registration Number POLYNOMIAL = X8 + X5 + X4 + 1 1ST STAGE X0 2ND STAGE X1 3RD STAGE X2 4TH STAGE X3 5TH STAGE X4 6TH STAGE X5 7TH STAGE X6 8TH STAGE X7 X8 INPUT DATA Figure 3. 1-Wire CRC Generator Memory Description The memory map of the DS28EA00 is shown in Figure 4.
PAGE 8
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Register Detailed Descriptions Temperature Readout Register Bitmap ADDRRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0h 23 22 21 20 2-1 2-2 2-3 2-4 LS BYTE S 26 25 24 MS BYTE 1h S S S S Temperature Alarm Registers Bitmap ADDRRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 2h S 26 25 24 23 22 21 20 HIGH ALARM (TH) 3h S 26 25 24 23 22 21 20 LOW ALARM (TL) Table 1.
PAGE 9
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Configuration Register ADDRRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 4h 0 R1 R0 1 1 1 1 1 The functional assignments of the individual bits are explained in the table below. Bits [4:0] and bit 7 have BIT DESCRIPTION R1, R0: Temperature Converter Resolution no function and cannot be changed by the user. As a factory default, the device operates in 12-bit resolution.
PAGE 10
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO The power-on default chain state is OFF, where PIOA and PIOB are solely controlled through the PIO Access Read and Write commands. In the chain ON state, PIOA is pulled high to the device’s internal VDD supply through an approximately 40kΩ resistor, applying a logic 1 to the PIOB (EN) pin of the next device. Only in the ON state does a DS28EA00 respond to the Conditional Read ROM command, provided its EN is at logic 0.
PAGE 11
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO PIO Status Bit Assignment BIT 7 BIT 6 BIT 5 BIT 4 COMPLEMENT OF B3 TO B0 BIT 3 BIT 2 BIT 1 BIT 0 PIOB OUTPUT LATCH STATE PIOB PIN STATE PIOA OUTPUT LATCH STATE PIOA PIN STATE PIO Output Data Bit Assignment BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 X X X X X X PIOB PIOA PIO Access Read [F5h] PIO Access Write [A5h] This command reads the PIO logical status and reports it together with the state of the PIO out
PAGE 12
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO MOST SIGNIFICANT 2 BITS OF INVERTED PIO OUTPUT DATA BYTE LEAST SIGNIFICANT 2 BITS OF CONFIRMATION BYTE (AAh) IO VTH tREH + X PIO Figure 7. PIO Access Write Timing Diagram as the new PIO output state arrives in its true form at the PIO pin. To protect the transmission against data errors, the master must repeat the PIO output data byte in its inverted form. Only if the transmission was error-free can the PIO status change.
PAGE 13
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO FROM ROM FUNCTIONS FLOWCHART (FIGURE 11) BUS MASTER Tx CONTROL FUNCTION COMMAND 4Eh WRITE SCRATCHPAD? BEh READ SCRATCHPAD? N Y DS28EA00 SETS BYTE ADDRESS = 0 MASTER Tx DATA BYTE TO SCRATCHPAD MASTER Rx BYTE FROM SCRATCHPAD Y MASTER Tx RESET? Y Y COPY COMPLETED? TO FIGURE 9b N MASTER ACTIVATES STRONG PULLUP FOR tPROG DS28EA00 COPIES SCRATCHPAD DATA TO EEPROM Y N N N VDD POWERED? DS28EA00 STARTS COPY TO EEPROM N MASTER D
PAGE 14
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO 44h CONVERT TEMPERATURE FROM FIGURE 9a MASTER DECISION. THE MASTER NEEDS TO KNOW WHETHER VDD POWER IS AVAILABLE.
PAGE 15
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO FROM FIGURE 9b B8h RECALL EEPROM? N F5h PIO ACCESS READ? A5h PIO ACCESS WRITE? N Y Y Y DS28EA00 STARTS RECALL EEPROM TO SCRATCHPAD RECALL COMPLETED? TO FIGURE 9d N BUS MASTER Tx NEW PIO OUTPUT DATA BYTE BUS MASTER Tx INVERTED NEW PIO OUTPUT DATA BYTE Y N DS28EA00 SAMPLES PIO PIN * TRANSMISSION OK? MASTER Rx "0"s N Y DS28EA00 UPDATES PIO * MASTER Rx "1"s BUS MASTER Rx CONFIRMATION AAh BUS MASTER Rx PIO PIN STATUS BUS MAS
PAGE 16
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO FROM FIGURE 9c 99h CHAIN COMMAND? N Y MASTER Tx CHAIN CONTROL BYTE MASTER Tx RESET? N MASTER Tx INVERTED CHAIN CONTROL BYTE TRANSMISSION ERROR? Y ERROR DEFINED AS: REPEATED CONTROL BYTE NOT EQUAL TO INVERTED CONTROL BYTE MASTER Rx "1"s Y N CONTROL BYTE VALID? VALID CHAIN CONTROL BYTE CODES: 3Ch OFF 5Ah ON 96h DONE N Y DS28EA00 UPDATES CHAIN STATE MASTER Rx CONFIRMATION CODE AAh N MASTER Tx RESET? Y MASTER Rx INVERTED CHAIN
PAGE 17
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO 1-Wire Bus System 1-Wire physical interface enhancement to improve noise immunity. The value of the pullup resistor primarily depends on the network size and load conditions. The DS28EA00 requires a pullup resistor of 2.2kΩ (max) at any speed. The idle state for the 1-Wire bus is high. If for any reason a transaction needs to be suspended, the bus must be left in the idle state if the transaction is to resume.
PAGE 18
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO 1-Wire ROM Function Commands Once the bus master has detected a presence, it can issue one of the eight ROM function commands that the DS28EA00 supports. All ROM function commands are 8 bits long. A list of these commands follows (refer to the flowchart in Figure 11). Read ROM [33h] This command allows the bus master to read the DS28EA00’s 8-bit family code, unique 48-bit serial number, and 8-bit CRC.
PAGE 19
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Skip ROM [CCh] This command can save time in a single-drop bus system by allowing the bus master to access the control functions without providing the 64-bit ROM code. If more than one slave is present on the bus and, for example, a read command is issued following the Skip ROM command, data collision occurs on the bus as multiple slaves transmit simultaneously (open-drain pulldowns produce a wired-AND result).
PAGE 20
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO BUS MASTER Tx RESET PULSE FROM FIGURE 11b FROM CONTROL FUNCTIONS FLOWCHART (FIGURE 9) OD RESET PULSE? N OD = 0 Y BUS MASTER Tx ROM FUNCTION COMMAND 33h READ ROM COMMAND? DS28EA00 Tx PRESENCE PULSE N Y 55h MATCH ROM COMMAND? F0h SEARCH ROM COMMAND? N Y ECh CONDITIONAL SEARCH COMMAND? N Y N TO FIGURE 11b Y N TEMPERATURE ALARM? Y DS28EA00 Tx FAMILY CODE (1 BYTE) MASTER Tx BIT 0 BIT 0 MATCH? N N DS28EA00 Tx BIT 0 DS28EA
PAGE 21
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO TO FIGURE 11a FROM FIGURE 11a 0Fh CONDITIONAL READ ROM? N Y CHAIN = ON? CCh SKIP ROM COMMAND? 3Ch OVERDRIVESKIP ROM? N Y N 69h OVERDRIVEMATCH ROM? Y Y OD = 1 OD = 1 N N Y MASTER Tx BIT 0 EN = LOW? N MASTER Tx RESET? Y N Y BIT 0 MATCH? DS28EA00 Tx FAMILY CODE (1 BYTE) * OD = 0 Y MASTER Tx BIT 1 DS28EA00 Tx SERIAL NUMBER (6 BYTES) DS28EA00 Tx CRC BYTE N MASTER Tx RESET? N Y BIT 1 MATCH? N * OD = 0 Y MASTER Tx
PAGE 22
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO 1-Wire Signaling device is in overdrive mode and tRSTL is between 80µs and 480µs, the device resets, but the communication speed is undetermined. After the bus master has released the line, it goes into receive mode. Now the 1-Wire bus is pulled to VPUP through the pullup resistor, or in the case of a DS2482x00 or DS2480B driver, by active circuitry.
PAGE 23
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO WRITE-ONE TIME SLOT tW1L VPUP VIHMASTER VTH VTL VILMAX 0V ε tF tSLOT RESISTOR MASTER WRITE-ZERO TIME SLOT tW0L VPUP VIHMASTER VTH VTL VILMAX 0V ε tF tREC tSLOT RESISTOR MASTER READ-DATA TIME SLOT tMSR tRL VPUP VIHMASTER VTH MASTER SAMPLING WINDOW VTL VILMAX 0V δ tF tREC tSLOT RESISTOR MASTER DS28EA00 Figure 13.
PAGE 24
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Master-to-Slave For a write-one time slot, the voltage on the data line must have crossed the VTH threshold before the writeone low time tW1LMAX is expired. For a write-zero time slot, the voltage on the data line must stay below the VTH threshold until the write-zero low time tW0LMIN is expired. For the most reliable communication, the voltage on the data line should not exceed VILMAX during the entire tW0L or tW1L window.
PAGE 25
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO tREH tREH VPUP VTH VHY CASE A CASE B CASE C 0V tGL tGL Figure 14. Noise Suppression Scheme through RCO of the PIOA pin charges the PIOA/PIOB connections to logic 1 level at all devices except for the first device in the chain.
PAGE 26
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Command-Specific 1-Wire Communication Protocol—Legend SYMBOL RST DESCRIPTION 1-Wire reset pulse generated by master PD 1-Wire presence pulse generated by slave SELECT Command and data to satisfy the ROM function protocol SKIPR ROM function command: “Skip ROM” CDRR ROM function command: “Conditional Read ROM” WSP Command: “Write Scratchpad” RSP Command: “Read Scratchpad” CPSP Command: “Copy Scratchpad” CTEMP RPM Command: “Conve
PAGE 27
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO 1-Wire Communication Examples Write Scratchpad RST PD SELECT WSP <3 Bytes> RST PD Read Scratchpad RST PD SELECT RSP <8 Bytes> CRC FF Loop Copy Scratchpad (Parasite Powered) RST PD SELECT CPS Wait tPROGMAX FF Loop During the wait, the master should activate a low-impedance bypass to the 1-Wire pullup resistor.
PAGE 28
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO 1-Wire Communication Examples (continued) PIO Access Write (Invalid Data Byte) RST PD SELECT PIOW FF Loop The PIO Access Write command is ignored by the device while in chain ON or chain DONE state.
PAGE 29
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Revision History REVISION NUMBER REVISION DATE 0 1/07 Initial release. — 1 6/07 Changed the storage temperature range in the Absolute Maximum Ratings section from -40°C to +85°C to -55°C to +125°C. 2 2 4/09 Created newer template-style data sheet. DESCRIPTION PAGES CHANGED All Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.