DS75 MAXIM | Alldatasheet

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Technical content

Features

  • Temperature Measurements Require No External Components
  • Measures Temperatures from -55°C to +125°C (-67°F to +257°F)
  • ±2°C Accuracy Over a -25°C to +100°C Range
  • Thermometer Resolution is User-Configurable from Nine (Default) to 12 Bits (0.5°C to 0.0625°C Resolution)
  • 9-Bit Conversion Time is 150ms (Max)
  • Thermostatic Settings are User-Definable
  • Data is Read/Written Via 2-Wire Serial (Interface (SDA and SCL Pins)
  • Multidrop Capability Simplifies Distributed Temperature-Sensing Applications
  • Wide Power-Supply Range (+2.7V to +5.5V).
  • Pin/software Compatible with the LM75
  • Available in 8-Pin µ MAX and SO Packages and as a 1.5mm x 1.3mm Flip Chip. See Table 1 for Ordering Information
  • Applications Include Personal Computers, Cellular Base Stations, Office Equipment, or Any Thermally Sensitive System 19-7848; Rev 1; 2/08 SDA Open-Drain Data I/O SCL Clock Input GND Ground O.S. Open-Drain Thermostat Output A0 Address Input A1 Address Input A2 Address Input VDD Power Supply VDD SDA SCL O.S. GND DS75 DS75S+ (8-Pin SO — 150mil) TOP VIEW VDD SDA SCL O.S. GND DS75 DS75U+ (µMAX) DS75 Digital Thermometer and Thermostat Pin Description Pin Configuration

Table 1. Ordering Information Table 2. Detailed Pin Description 1 SDA Data input/output pin for 2-wire serial communication port. Open drain. 2 SCL Clock input pin for 2-wire serial communication port. 3 O.S. Thermostat output. Open drain. 8 VDD Supply Voltage. +2.7V to +5.5V supply pin.

Figure 1. DS75 Functional Block Diagram

Voltage on any other pin, (-55°C to +125°C; 2.7V ≤ VDD ≤ 5.5V) PARAMETER SYMBOL CONDITION MIN MAX UNITS Supply Voltage VDD 2.7 5.5 V Thermometer Error TERR -25 to +100 (Note 2) ± 2.0 °C-55 to +125 (Note 2) ± 3.0 Input Logic High VIH (Note 1) 0.7 x VDD VDD + 0.5 V Input Logic Low VIL (Note 1) -0.5 0.3 x VDD V SDA Output Logic Low Voltage VOL1 3mA sink current (Note 1) 0 0.4 VVOL2 6mA sink current (Note 1) 0 0.6 O.S. Saturation Voltage VOL 4mA sink current (Notes 1, 2) 0.8 V Input current each I/O pin 0.4 < VI/O< 0.9 VDD -10 +10 µA I/O Capacitance CI/O 10 pF Standby Current IDD1 (Notes 3, 4) 1 µA Active Current IDD Active temp conversions (Notes 3, 4) 1000 µACommunication only (Notes 3, 4) 100 DS75 Digital Thermometer and Thermostat www.maximintegrated.com Maxim Integrated │ 4 Absolute Maximum Ratings *Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

(-55°C to +125°C; 2.7V ≤ VDD ≤ 5.5V) Note 1: All voltages are referenced to ground. rated current. Note 3: IDD specified with O.S. pin open. Note 4: IDD specified with VDD at 5.0V and SDA, VSCL = 5.0V, 0°C to 70°C. Note 5: See Timing Diagram in Figure 2. All timing is referenced to 0.9 x V DD and 0.1 x VDD. Note 6: After this period, the first clock pulse is generated. Note 7: For example, if CB = 300pF, then tR[min] = tF[min] = 50ns. PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS Resolution 9 12 bits Temperature Conversion Time tCONVT 9-bit conversions 150 ms10-bit conversions 300 11-bit conversions 600 12-bit conversions 1200 SCL Frequency fSCL 400 kHz Bus Free Time Between a STOP and START Condition tBUF (Note 5) 1.3 µs START and Repeated START Hold Time from Falling SCL tHD:STA (Notes 5, 6) 0.6 µs Low Period of SCL tLOW (Note 5) 1.3 µs High Period of SCL tHIGH (Note 5) 0.6 µs Repeated START Condition Setup Time to Rising SCL tSU:STA (Note 5) 0.6 µs Data-Out Hold Time from Falling SCL tHD:DAT (Note 5) 0 0.9 µs Data-In Setup Time to Rising SCL tSU:DAT (Note 5) 100 ns Rise Time of SDA and SCL tR (Notes 5, 7) 20 + 0.1CB 1000 ns Fall Time of SDA and SCL tF (Notes 5, 7) 20 + 0.1CB 300 ns STOP Setup Time to Rising SCL tSU:STO (Note 5) 0.6 µs Capacitive Load for Each Bus Line CB 400 pF Input Capacitance CI 5 pF DS75 Digital Thermometer and Thermostat www.maximintegrated.com Maxim Integrated │ 5

CONFIGURATION REGISTER section of this data sheet. perature register does not affect the operation in progress.

11 MSbs (bits 15 through 5) of the temperature register

will contain data, and all unused LSbs will contain 0s. data and the corresponding temperatures. Figure 2. Timing Diagram NOTE: THE DS75 DOES NOT DELAY THE SDA LINE INTERNALLY WITH RESPECT TO SCL FOR ANY LENGTH OF TIME.

on user-programmable trip-points (T OS and T HYST). erup, so standalone operation is not possible. the configuration and at power-up the fault tolerance is 1. values in the T OS and T HYST registers, and then O.S. registers can be used for general storage of system data. Figure 3. Temperature, TH, and TL Register Format Table 3. 12-Bit Resolution Temperature/Data Relationship

programmed to operate with any amount of hysteresis. tor mode operation with FT = 2 is illustrated in Figure 4. TOS, clear, THYST, clear, TOS, clear, THYST, clear, etc.). Figure 4. O.S. Output Operation Example

volatile, and thus powers up in its default state. Figure 5. Configuration Register Table 4. Configuration Register Bit Descriptions Table 5. Resolution Configuration Table 6. Fault Tolerance Configuration The master can write to this bit, but it will always read out as a 0. Sets the thermostat fault tolerance (see Table 6). Sets the thermostat fault tolerance (see Table 6). POL = 0 — O.S. is active low. POL = 1 — O.S. is active high. See the OPERATION–Thermostat section for a detailed description of these modes. SD = 0 — Active conversion and thermostat operation. See the SHUTDOWN MODE section for a detailed description of this mode.

0 R1 R0 F1 F0 POL TM SD

remain pointed at the same register until it is changed. register is being written to twice in a row. ately without resetting the pointer. pin. All communication is MSb first. erates the SCL signal and START and STOP conditions. DS75 always functions as a slave. Bus Idle or Not Busy: Both SDA and SCL remain high. (if the SCL output is open-drain). issued, the master releases the bus to its idle state. SDA line high during the ACK clock cycle. Table 7. Pointer Definition

General 2-Wire Information

  • All data is transmitted MSb first over the 2-wire bus.
  • One bit of data is transmitted on the 2-wire bus each SCL period.
  • A pullup resistor is required on the SDA line and, when the bus is idle, both SDA and SCL must remain in a logic-high state.
  • All bus communication must be initiated with a START condition and terminated with a STOP condition. During a START or STOP is the only time SDA is allowed to change states while SCL is high. At all other times, changes on the SDA line can only occur when SCL is low: SDA must remain stable when SCL is high.
  • After every 8-bit (1-byte) transfer, the receiving device must answer with an ACK (or NACK), which takes one SCL period. Therefore, nine clocks are required for every one-byte data transfer. Writing to the DS75 To write to the DS75, the master must generate a START followed by an address byte containing the DS75 bus address. The value of the R/ W bit must be a 0, which indicates that a write is about to take place. The DS75 will respond with an ACK after receiving the address byte. This must be followed by a pointer byte from the master, which tells the DS75 which register is being written to. The DS75 will again respond with an ACK after receiving the pointer byte. Following this ACK the master device must immediately begin transmitting data to the DS75. When writing to the configuration register, the master must send one byte of data (see Figure 9a), and when writing to the TOS or THYST registers the master must send two bytes of data (see Figure 9 b). After receiving each data byte, the DS75 will respond with an ACK, and the transaction is finished with a STOP from the master. Reading from the DS75 When reading from the DS75, if the pointer was already pointed to the desired register during a previous trans - action, the read can be performed immediately without changing the pointer setting. In this case the master sends a START followed by an address byte containing the DS75 bus address. The R/ W bit must be a 1, which tells the DS75 that a read is being performed. After the DS75 sends an ACK in response to the address byte, the DS75 will begin transmitting the requested data on the next clock cycle. When reading from the configura - tion register, the DS75 will transmit one byte of data, after which the master must respond with a NACK followed by a STOP (see Figure 9c). For two-byte reads (i.e., from the Temperature, TOS or THYST register), the DS75 will trans- mit two bytes of data, and the master must respond to the first data byte with an ACK and to the second byte with a NACK followed by a STOP (see Figure 9d). If only the most significant byte of data is needed, the master can issue a NACK followed by a STOP after reading the first data byte in which case the transaction will be the same as for a read from the configuration register. If the pointer is not already pointing to the desired register, the pointer must first be updated as shown in Figure 9e, which shows a pointer update followed by a single-byte read. The value of the R/ W bit in the initial address byte is a 0 (“write”) since the master is going to write a pointer byte to the DS75. After the DS75 to the address byte with an ACK, the master sends a pointer byte that corresponds to the desired register. The master must then perform a repeated start followed by a standard one or two byte read sequence (with R/ W =1) as described in the previ - ous paragraph. DS75 Digital Thermometer and Thermostat www.maximintegrated.com Maxim Integrated │ 12

Figure 9. 2-Wire Interface Timing

0 10/07 Initial release — 1 2/08 Deleted all references to flip-chip package and added registered trademark symbol to µMAX 1, 2 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. DS75 Digital Thermometer and Thermostat © 2008 Maxim Integrated Products, Inc. │ 14

Revision History

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