Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsDS75S+

1 of 14 022108

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 μMAX

and SO

Packages. See Table 1 for Ordering

Information

 Applications Include Personal Computers,

Cellular Base Stations, Office Equipment, or

Any Thermally Sensitive System

PIN ASSIGNMENT

PIN DESCRIPTION

SDA – Open-Drain Data I/O

SCL – Clock Input

GND – Ground

O.S. – Open-Drain Thermostat Output

– Address Input

– Power Supply

DESCRIPTION

The DS75 digital thermometer and thermostat provides 9, 10, 11, or 12-bit digital temperature readings

over a -55°C to +125°C range with ±2°C accuracy over a -25°C to +100°C range. At power-up, the

DS75 defaults to 9-bit resolution for software compatibility with the LM75. Communication with the

DS75 is achieved via a simple 2–wire serial interface. Three address pins allow up to eight DS75 devices

to operate on the same 2–wire bus, which greatly simplifies distributed temperature sensing applications.

The DS75 thermostat has a dedicated open–drain output (O.S.) and programmable fault tolerance, which

allows the user to define the number of consecutive error conditions that must occur before O.S is

activated. There are two thermostatic operating modes that control thermostat operation based on user-

defined trip-points (T

and T

HYST

A block diagram of the DS75 is shown in Figure 1 and detailed pin descriptions are given in Table 2.

DS75

Digital Thermometer and Thermostat

www.maxim-ic.com

DS75U+ (

MAX)

GND

O.S.

DS75

DS75S+ (8-Pin SO — 150mil)

GND

O.S.

DS75

µMAX is a registered trademark of Maxim Integrated Products, Inc.

Summary of content (14 pages)

PAGE 1
DS75 Digital Thermometer and Thermostat www.maxim-ic.com FEATURES 1 SCL 2 O.S. 3 GND 4 8 VDD 7 A0 6 A1 5 A2 DS75S+ (8-Pin SO — 150mil) SDA 1 SCL 2 O.S. GND 3 4 DS75 SDA DS75 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 UserConfigurable from Nine (Default) to 12 Bits (0.5°C to 0.
PAGE 2
DS75 Table 1.
PAGE 3
DS75 Figure 1. DS75 FUNCTIONAL BLOCK DIAGRAM PRECISION REFERENCE OVERSAMPLING MODULATOR DIGITAL DECIMATOR VDD SCL SDA A0 A1 A2 CONFIGURATION REGISTER ADDRESS AND I/O CONTROL TEMPERATURE REGISTER RP O.S.
PAGE 4
DS75 ABSOLUTE MAXIMUM RATINGS* Voltage on VDD, Relative to Ground Voltage on any other pin, Relative to Ground Operating Temperature Storage Temperature Soldering Temperature –0.3V to +7.0V –0.3V to (V DD + 0.3V) –55°C to +125°C –55°C to +125°C +260°C for 10 seconds * These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied.
PAGE 5
DS75 AC ELECTRICAL CHARACTERISTICS PARAMETER Resolution Temperature Conversion Time SCL Frequency Bus Free Time Between a STOP and START Condition START and Repeated START Hold Time from Falling SCL Low Period of SCL High Period of SCL Repeated START Condition Setup Time to Rising SCL Data-Out Hold Time from Falling SCL Data-In Setup Time to Rising SCL Rise Time of SDA and SCL Fall Time of SDA and SCL STOP Setup Time to Rising SCL Capacitive Load for Each Bus Line Input Capacitance SYMBOL tCONVT fSCL tB
PAGE 6
DS75 Figure 2. TIMING DIAGRAM Note: The DS75 does not delay the SDA line internally with respect to SCL for any length of time. OPERATION–MEASURING TEMPERATURE The DS75 measures temperature using a bandgap temperature sensing architecture. An on-board deltasigma analog-to-digital converter (ADC) converts the measured temperature to a digital value that is calibrated in degrees centigrade; for Fahrenheit applications a lookup table or conversion routine must be used.
PAGE 7
DS75 Figure 3. TEMPERATURE, TH, and TL REGISTER FORMAT bit 15 MS Byte LS Byte bit 14 6 S 2 bit 7 bit 6 2 -1 2 -2 bit 13 2 5 bit 5 2 -3 bit 12 2 4 bit 4 2 -4 bit 11 2 3 bit 10 2 2 bit 9 2 1 bit 8 20 bit 3 bit 2 bit 1 bit 0 0 0 0 0 Table 3. 12-BIT RESOLUTION TEMPERATURE/DATA RELATIONSHIP TEMPERATURE (°C) +125 +25.0625 +10.125 +0.5 0 -0.5 -10.125 -25.
PAGE 8
DS75 compared to the values in the TOS and THYST registers, and then O.S. is updated based on the result of the comparison and the operating mode. The number of TOS and THYST bits used during the thermostat comparison is equal to the conversion resolution set by the R1 and R0 bits in the configuration register. For example, it the resolution is 9 bits, only the 9 MSbs of TOS and THYST will be used by the thermostat comparator. The active state of the O.S.
PAGE 9
DS75 CONFIGURATION REGISTER The configuration register allows the user to program various DS75 options such as conversion resolution, thermostat fault tolerance, thermostat polarity, thermostat operating mode, and shutdown mode. The configuration register is arranged as shown in Figure 5 and detailed descriptions of each bit are provided in Table 4. The user has read/write access to all bits in the configuration register except the MSb, which is a reserved read-only bit.
PAGE 10
DS75 Table 6. Fault Tolerance Configuration F1 F0 0 0 1 1 0 1 0 1 CONSECUTIVE OUT-OF-LIMITS CONVERSIONS TO TRIGGER O.S. 1 2 4 6 REGISTER POINTER The four DS75 registers each have a unique two-bit pointer designation, which is defined in Table 7. When reading from or writing to the DS75, the user must “point” the DS75 to the register that is to be accessed. When reading from the DS75, once the pointer is set, it will remain pointed at the same register until it is changed.
PAGE 11
DS75 START Condition: Signal generated by the master to indicate the beginning of a data transfer on the bus. The master generates a START condition by pulling SDA from high to low while SCL is high (see Figure 6). A “repeated” START is sometimes used at the end of a data transfer (instead of a STOP) to indicate that the master will perform another operation. STOP Condition: Signal generated by the master to indicate the end of a data transfer on the bus.
PAGE 12
DS75 0 0 0 0 0 0 P1 P0 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.
PAGE 13
S 1 0 1 A ACK (DS75) A2 A1 A0 W Address Byte 0 S 1 0 1 A ACK (DS75) A2 A1 A0 W Address Byte 0 0 0 0 0 0 0 0 0 0 0 Pointer Byte 0 Pointer Byte 0 A ACK (DS75) SCL 13 of 14 1 START S 0 1 A2 A1 A0 Address Byte 0 A Data Byte (from DS75) P NACK STOP (Master) D7 D6 D5 D4 D3 D2 D1 D0 N ACK (DS75) R 1 START S 0 1 A2 A1 A0 Address Byte 0 A SCL SDA 1 START S 0 1 A ACK (DS75) A2 A1 A0 W Address Byte 0 0 0 0 0 Pointer Byte 0 0 MS Data Byte (from DS7
PAGE 14
DS75 REVISION HISTORY REVISION DATE 022108 DESCRIPTION Deleted all references to flip-chip package. Added registered trademark symbol to µMAX.