19-2120; Rev 0; 8/01 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface The MAX6633/MAX6634/MAX6635 combine a temperature sensor, a programmable overtemperature alarm, and an SMBus™/I2C™-compatible serial interface into a single package. They convert their die temperatures into digital values using internal analog-to-digital converters (ADCs). The result of the conversion is then held in a temperature register as a 12-bit + sign value, allowing 0.0625°C resolution, readable at any time through the serial interface. The devices are capable of reading temperatures up to +150°C. The MAX6633/MAX6634/MAX6635 feature a shutdown mode that saves power by turning off everything except the power-on reset (POR) and the serial interface. The devices can be configured to separate addresses, allowing multiple devices to be used on the same bus. The MAX6633 has four address pins, allowing up to 16 devices to be connected to a single bus. The MAX6634 has three address pins, allowing up to eight devices to be connected to a single bus. The MAX6635 has two address pins, allowing up to four devices to be connected to a single bus. The MAX6633/MAX6634/MAX6635 make temperature data available for transfer over the serial interface. The MAX6634 incorporates a dual-mode ALERT output (open drain) and can serve as an upgraded alternative to the LM75. The MAX6635 includes an ALERT output and an OVERT output (both open drain) and can function as an upgraded replacement for the LM76 in most applications. The MAX6634/MAX6635 feature user-programmable temperature thresholds. All three devices come in an 8-pin SO package. Applications Features ♦ +3V to +5.5V Supply Range ♦ Accuracy ±1°C max (0°C to +50°C) ±1.5°C max (-20°C to +85°C) ±2.5°C max (-40°C to +125°C) ±2.5°C typ (+150°C) ♦ User-Programmable Temperature Thresholds (MAX6634/MAX6635) ♦ User-Configurable Alarm Output(s) (MAX6634/MAX6635) ♦ Ability to Respond to SMBus/I2C-Compatible Alert Response Address (MAX6634/MAX6635) ♦ OVERT Output for System Shutdown (MAX6635) ♦ Multiple Devices per Bus 16 devices (MAX6633) 8 devices (MAX6634) 4 devices (MAX6635) Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX6633MSA -55°C to +150°C 8 SO MAX6634MSA -55°C to +150°C 8 SO MAX6635MSA -55°C to +150°C 8 SO Typical Operating Circuit VCC 0.1µF +3.0V TO +5.5V 8 VCC 10kΩ 1kΩ 1kΩ 10kΩ Battery Temperature Alarms PC Temperature Control ALERT Automotive Equipment 5 MAX6635 SDA 1 Pin Configurations appear at end of data sheet. SCL OVERT SMBus is a trademark of Intel Corp. I2C is a trademark of Philips Corp. 2 3 TO INTERRUPT CONTROLLER TO SMBus/I2C MASTER TO SYSTEM SHUTDOWN A0 A1 GND 7 6 4 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX6633/MAX6634/MAX6635 General Description MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface ABSOLUTE MAXIMUM RATINGS VCC, SDA, SCL ......................................................-0.3V to +6.0V All Other Pins ................................................-0.3V to VCC +0.3V SDA, ALERT, OVERT Current .............................-1mA to +50mA ESD Protection (Human Body Model)................................2000V Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 5.88mW/°C above +70°C)................471mW Junction Temperature ......................................................+150°C Operating Temperature Range .........................-55°C to +150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) ................................+300°C 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. ELECTRICAL CHARACTERISTICS (VCC = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are VCC = +3.3V, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS Supply Range VCC Accuracy (Note 1) 3.0 0°C ≤ TA = ≤ +50°C, VCC = +3.3V -1.0 ±0.4 +1.0 -20°C ≤ TA = ≤ +85°C, VCC = +3.3V -1.5 ±0.6 +1.5 -40°C ≤ TA = ≤ 125°C, VCC = +3.3V -2.5 ±1.0 +2.5 TA = -55°C, VCC = +3.3V -2.8 ±1.5 +2.8 ±2.5 TA = +150°C, VCC = +3.3V Power-Supply Rejection Ratio PSRR 0.2 POR Threshold Hysteresis 0.5 90 Supply Current in Shutdown Average Operating Current Peak Operating Current (Note 2) °C °C/V mV VCC = +3.0V, SMBus inactive 12 20 VCC = +5.5V, SMBus inactive 20 30 VCC = +3.0V, SMBus inactive 150 VCC = +5.5V, SMBus inactive 200 VCC = +3.0V, SMBus inactive 270 350 VCC = +5.5V, SMBus inactive 350 700 2 2.4 Hz 0.65 V Conversion Rate 1.4 µA µA µA DIGITAL INTERFACE Logic Input Low Voltage Logic Input High Voltage Input Leakage Current VIL VIH II_LEAK VCC = +3.0V to +5.5V VCC = +3V 2.2 VCC = +5.5V 2.4 Output Low Sink Current IOL Output Leakage Current IO_LEAK ALERT, OVERT at VCC 2 CIN ±1 VIN = GND or VCC VOL = 0.6V (SMBDATA, ALERT, OVERT) Input Capacitance V 6 µA mA ±1 5 _______________________________________________________________________________________ µA pF 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface (VCC = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are VCC = +3.3V, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 100 kHz SMBus TIMING (Note 3, Figures 1, 2, and 3) Serial Clock Frequency fSCL 10 Bus Free Time Between STOP and START Condition tBUF 4.7 µs 4.7 µs 4.7 µs START Condition Setup Time Repeat START Condition Setup Time tSU:STA 90% to 90% START Condition Hold Time tHD:STA 10% of SMBDATA to 90% of SMBCLK 4 µs STOP Condition Setup Time tSU:STO 90% of SMBCLK to 10% of SMBDATA 4 µs Data Setup Time tSU:DAT 90% of SMBDATA to 10% of SMBCLK 250 ns Data Hold Time (Note 4) tHD:DAT 300 ns Receive SCL/SDA Rise Time tR 1 µs SCL/SDA Fall Time (Note 4) tF 300 ns Clock Low Period tLOW 10% to 10% 4.7 µs Clock High Period tHIGH 90% to 90% 4 µs SMBus Timeout Note 1: Note 2: Note 3: Note 4: 25 48 ms Guaranteed by design and characterization. Peak operating current measured during conversion. See Figure 4. Guaranteed by design, not production tested. A master device must provide a hold time of at least 300ns for the SDA signal in order to bridge the undefined region of SCL’s falling edge. _______________________________________________________________________________________ 3 MAX6633/MAX6634/MAX6635 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) 20 10 300 VCC = +5.5V 200 100 VCC = +3.3V 3 VIN = 200mVp-p 2 1 VIN = 200mVp-p 0 VCC = +3.3V 0 -55 0 -1 0 110 55 165 -55 0 TEMPERATURE (°C) 55 110 60 50 40 30 VCC = +5.5V DEVICE IMMERSED IN +85°C FLUORINERT BATH MAX6633/4/5 toc05 70 3 TEMPERATURE ERROR (°C) TEMPERATURE (°C) 80 10M TEMPERATURE ERROR vs. TEMPERATURE MAX6633/4/5 toc04 90 10k SUPPLY NOISE FREQUENCY (Hz) RESPONSE TO THERMAL SHOCK 10 10 165 TEMPERATURE (°C) 100 20 VIN = SQUARE WAVE APPLIED TO VCC WITH NO BYPASS CAPACITOR 4 TEMPERATURE ERROR (°C) VCC = +5.5V 5 MAX6633/4/5 toc02 40 400 AVERAGE SUPPLY CURRENT (µA) MAX6633/4/5 toc01 50 30 TEMPERATURE ERROR vs. SUPPLY NOISE FREQUENCY AVERAGE SUPPLY CURRENT vs. TEMPERATURE 2 VCC = +3.3V 0 VCC = +5.5V -2 0 0 5 10 TIME (s) 15 20 -3 -40 0 40 80 120 TEMPERATURE (°C) 4 MAX6633/4/5 toc03 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE SHUTDOWN SUPPLY CURRENT (µA) MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface _______________________________________________________________________________________ 160 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface PIN MAX6633 MAX6634 MAX6635 NAME FUNCTION 1 1 1 SDA Serial Data Input/Output. Open drain. 2 2 2 SCL Serial Clock Input 3 — — A3 4 4 4 GND 5 5 — A2 Address Pin 6 6 6 A1 Address Pin 7 7 7 A0 Address Pin 8 8 8 VCC — 3 5 ALERT ALERT Output. Open drain. — — 3 OVERT OVERT Output. Open drain. Detailed Description The MAX6633/MAX6634/MAX6635 continuously convert their die temperatures into digital values using their integrated ADCs. The resulting data is readable at any time through the SMBus/I2C-compatible serial interface. The device functions as a slave on the SMBus interface, supporting Write Byte, Write Word, Read Byte, and Read Word commands. Separate addresses can be configured using the individual address pins. Figures 5, 6, and 7 show the functional diagrams of the MAX6633/MAX6634/MAX6635, respectively. SMBus/I2C-Compatible Operation The MAX6633/MAX6634/MAX6635 are readable and programmable through their SMBus/I 2C-compatible serial interface. Figures 1, 2, and 3 show the timing details of the clock (SCL) and data (SDA) signals. The devices function as slaves on the SMBus and support Write Byte, Write Word, Read Byte, and Read Word commands. Figure 8 is the MAX6633/MAX6634/ MAX6635 programmer’s model. Addressing Separate addresses can be configured using the individual address pins. The address of each device is selected by connecting the address (A_) pins to one of two potentials: GND or VCC. The MAX6635 makes two address pins available (A0, A1), allowing up to four devices to be connected to a single bus line. The MAX6634 makes three address pins available (A0, A1, A2), allowing up to eight devices to be connected to a single bus line. The MAX6633 makes four address pins available (A0, A1, A2, A3), allowing as many as 16 Address Pin Ground Supply Voltage Input. +3.0V to +5.5V. Bypass VCC to GND with a 0.1µF capacitor. devices to be connected to a single bus line. Table 1 shows the full SMBus/I2C address for each device type. Control Registers (MAX6633) Three registers control the operation of the MAX6633 (Figure 5 and Tables 2 through 6). The Pointer register is the first addressed and determines which of the other two registers is acted upon. The other two are the Temperature and Configuration registers. The temperature value is stored as 12 bits plus a sign bit, read only, and contains the latest temperature data. The true register length is 16 bits, with the lower 3 unused in this part. The digital temperature data contained in the temperature register is in °C, using a two’s-complement format with 1LSB corresponding to 0.0625°C. The Configuration register is 8 bits, read/write, and contains the SMBus timeout disable bit, fault queue enable bit, and the shutdown bit. Control Registers (MAX6634) Six registers control the operation of the MAX6634 (Figure 6 and Tables 2 through 7). The pointer register is the first addressed and determines which of the other five registers is acted upon. The other five are the Temperature, Configuration, High-Temperature (T HIGH ), Low-Temperature (T LOW ), and Hysteresis (THYST) registers. The temperature value is stored as 12 bits plus a sign bit, read only, and contains the latest temperature data. The true register length is 16 bits, with the lowest 2 used as status bits, and the third bit (D2) is unused. The digital temperature data contained in the temperature register is in °C, using a two’s-complement format with 1LSB corresponding to 0.0625°C. _______________________________________________________________________________________ 5 MAX6633/MAX6634/MAX6635 Pin Description MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface Write Byte Format S ADDRESS WR 7 bits Slave Address: equivalent to chip-select line of a 3wire interface Write Word Format S ADDRESS ACK COMMAND ACK 8 bits Command Byte: selects register you are writing to ACK WR COMMAND 7 bits ACK 8 bits Slave Address: equivalent to chip-select line of a 3-wire interface Command Byte: selects register you are writing to DATA ACK P 8 bits Data Byte: data goes into the register set by the command byte DATA ACK DATA 8 bits 8 bits (MSB) (LSB) Data Bytes: data goes into the register set by the command byte ACK P Read Byte Format S ADDRESS WR ACK 7 bits Slave Address: equivalent to chip-select line Read Word Format S ADDRESS WR 7 bits ACK Slave Address: equivalent to chipselect line S = Start condition P = Stop condition COMMAND ACK 8 bits Command Byte: selects register you are reading from S ADDRESS RD ACK 7 bits Slave Address: repeated due to change in data-flow direction COMMAND 8 bits S ADDRESS 7 bits ACK Command Byte: selects register you are reading from RD ACK Slave Address: repeated due to change in data-flow direction DATA /// P 8 bits Data Byte: reads from the register set by the command byte DATA ACK DATA /// 8 bits 8 bits (MSB) (LSB) Data Bytes: reads from the register set by the command byte P Shaded = Slave transmission /// = Not acknowledged Figure 1. SMBus Protocols A tLOW B tHIGH C D E F G H I J K L M SMBCLK SMBDATA tSU:STA tHD:STA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW tSU:DAT tHD:DAT F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE I = SLAVE PULLS SMBDATA LINE LOW tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO MASTER K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION Figure 2. SMBus Write Timing Diagram 6 _______________________________________________________________________________________ 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface B tLOW C D E F G tHIGH H I J K L MAX6633/MAX6634/MAX6635 A M SMBCLK SMBDATA tSU:STA tHD:STA tSU:STO tSU:DAT A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO MASTER H = LSB OF DATA CLOCKED INTO MASTER I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLEAR PULSE tBUF L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION Figure 3. SMBus Read Timing Diagram CONVERSION PERIOD 0.5s MAX6633/MAX6634/MAX6635 0.25s ADC CONVERSION TIME MAX6633/MAX6634/MAX6635 Figure 4. ADC Conversion Timing Diagram The Configuration register is 8 bits, read/write, and contains the SMBus timeout disable bit, fault queue enable bit, the temperature alarm output polarity select bits, the interrupt mode select bit, and the shutdown bit. Registers THIGH and TLOW are 16 bits, read/write, and contain the values that trigger ALERT. Register THYST is 16 bits, read/write, and contains the values by which the temperature must rise or fall beyond THIGH or TLOW, before ALERT deasserts. Control Registers (MAX6635) Seven registers control the operation of the MAX6635 (Figure 7 and Tables 2 through 7). The Pointer register is the first addressed and determines which of the other six registers is acted upon. The other six are the Temperature, Configuration, High-Temperature (T HIGH ), Low-Temperature (T LOW ), Maximum Temperature (TMAX), and Hysteresis (THYST) registers. The temperature value is stored as 12 bits plus a sign bit, read only, and contains the latest temperature data. The true register length is 16 bits, with the lower three used as status bits. The digital temperature data contained in the temperature register is in °C, using a two’s-complement format with 1LSB corresponding to 0.0625°C. The Configuration register is 8 bits, read/write, and contains the SMBus timeout disable bit, fault queue enable bit, the temperature alarm output polarity select bits, the interrupt mode select bit, and the shutdown VCC 12 BIT + SIGN ADC CONFIGURATION TEMPERATURE SMBus INTERFACE SDA SCL A0 A1 A2 A3 Figure 5. MAX6633 Functional Diagram _______________________________________________________________________________________ 7 MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface VCC CMP ALERT 12 BIT + SIGN ADC CONFIGURATION CMP TEMPERATURE TLOW THIGH SDA SCL A0 A1 A2 SMBus INTERFACE Figure 6. MAX6634 Functional Diagram VCC CMP OVERT CMP ALERT 12 BIT + SIGN ADC CONFIGURATION TEMPERATURE CMP TMAX SMBus INTERFACE TLOW THIGH SDA SCL A0 A1 Figure 7. MAX6635 Functional Diagram 8 _______________________________________________________________________________________ 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface MAX6633/MAX6634/MAX6635 SDA INTERFACE SCL DATA ADDRESS POINTER REGISTER (SELECTS REGISTER FOR COMMUNICATION) TEMPERATURE (READ ONLY) POINTER = 00h CONFIGURATION (READ/WRITE, SETS OPERATING MODES) POINTER = 01h THYST SET POINT (READ/WRITE) POINTER = 02h (MAX6634/MAX6635 ONLY) TMAX SET POINT (READ/WRITE) POINTER = 03h (MAX6635 ONLY) TLOW SET POINT (READ/WRITE) POINTER = 04h (MAX6634/MAX6635 ONLY) THIGH SET POINT (READ/WRITE) POINTER = 05h (MAX6634/MAX6635 ONLY) Figure 8. MAX6633/MAX6634/MAX6635 Programmer’s Model _______________________________________________________________________________________ 9 MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface TMAX TMAX - THYST THIGH THIGH - THYST TLOW + THYST TLOW ALERT COMPARATOR MODE ALERT INTERRUPT MODE OVERT COMPARATOR MODE ONLY * * * * * *IN INTERRUPT MODE, READING THE DEVICE CLEARS ALERT. OTHERWISE, IT WOULD REMAIN LOW INDEFINITELY UNTIL CLEARED. Figure 9. Alarm Output and Reset Diagram bit. Registers THIGH and TLOW are 16 bits, read/write, and contain values that trigger ALERT and OVERT. Register THYST is 16 bits, read/write, and contains the values by which the temperature must rise or fall beyond T HIGH , T LOW , or T MAX , before ALERT or OVERT deassert. Temperature Conversion An on-chip bandgap reference produces a signal proportional to absolute temperature (PTAT), as well as the temperature-stable reference voltage necessary for the analog-to-digital conversion. The PTAT signal is digitized by the on-board ADC to a resolution of 0.0625°C. The resulting digital value is placed in the Temperature register. The temperature conversion runs continuously and asynchronously from the serial interface at a rate of 500ms per conversion. When the Temperature register is read, the conversion in progress is aborted. The bus transaction is completed by a stop condition. 10 Fault Queue (MAX6634/MAX6635) A programmable fault queue on the MAX6634/ MAX6635 eliminates spurious alarm activity in noisy environments. The queue sets the number of consecutive out-of-tolerance temperature readings that must occur before the ALERT or OVERT alarm outputs are toggled. An out-of-tolerance reading is above THIGH or TMAX or below TLOW. The fault queue depth defaults to 1 at power-up and may be programmed—through the Configuration register—to four consecutive conversions. Any time the conversion result is in tolerance, and the particular alarm output is not asserted, the queue is cleared, even if it contains some out-of-tolerance counts. Additionally, the fault queue automatically clears at power-up and in shutdown. Whenever the fault queue is cleared, the alarm outputs are deasserted. Figure 9 is the alarm output and reset diagram. ______________________________________________________________________________________ 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface VCC +3V TO +5.5V +12V HEATER FAN 8 10kΩ 3 8 4kΩ RELAY 5VDC, 20mA 125VAC, 1A OVERT MAX6634 ALERT 12V 300mA MOTOR LOGIC-LEVEL MOSFET MAX6635 3 2N3904 HEATER SUPPLY 4 4 Figure 10. Simple Thermostat Figure 11. Fan Controller Temperature Alert (MAX6634/MAX6635) ALERT has programmable polarity and two modes: comparator and interrupt. Polarity and mode are selected through the Configuration register (Table 4). The ALERT output is open drain. Interrupt Mode With ALERT in interrupt mode, the MAX6634/MAX6635 look for a THIGH or a TLOW fault. The ALERT pin asserts an alarm for an undertemperature fault, as well as for an overtemperature fault. Once either fault has occurred, it remains active until deasserted by a read of any register. The device then begins to look for a temperature change crossing the hysteresis level. The activation of ALERT is subject to the depth of the fault queue. For example: If THIGH is set to 100°C, THYST is set to 20°C, and the fault queue depth is set to 4, ALERT does not assert until four consecutive conversions exceed 100°C. If the temperature is then read through the I2C-compatible interface, ALERT deasserts. ALERT asserts again when four consecutive conversions are less than 80°C. Comparator Mode In comparator mode, ALERT is asserted when the number of consecutive conversions exceeding the value in the THIGH register, or lower than the value in the TLOW register, is equal to the depth of the fault queue. ALERT deasserts when the number of consecutive conversions less than THIGH - THYST or greater than TLOW + THYST is equal to the depth of the fault queue. For example: If THIGH is set to 100°C, TLOW is set to 80°C, and the fault queue depth is set to four, ALERT does not assert until four consecutive conversions exceed 100°C, or are below 80°C. ALERT only deasserts if four consecutive conversions are less than THIGH - THYST or greater than TLOW + THYST. Comparator mode allows autonomous clearing of an ALERT fault without the intervention of a master and is ideal to use for driving a thermostat (Figure 10). Overtemperature Alarm (MAX6635) The MAX6635 also includes an overtemperature output that is always in comparator mode. Whenever the temperature exceeds a value in the programmable TMAX register, OVERT is asserted. OVERT only deasserts after the temperature drops below TMAX - THYST. When the fault queue is activated, OVERT is subject to that queue, which sets the number of faults that must occur before OVERT asserts or deasserts. This helps prevent spurious alarms in noisy environments. Comparator mode also allows autonomous clearing of an OVERT fault without the intervention of a master and thus is ideal to use for driving a cooling fan (Figure 11). In this application, the polarity of OVERT is active high. Shutdown The MAX6633/MAX6634/MAX6635 feature a shutdown mode, accessible through the serial interface that saves power by turning off everything except the POR ______________________________________________________________________________________ 11 MAX6633/MAX6634/MAX6635 VCC +3V TO +5.5V MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface and the serial interface. Enter shutdown by programming the shutdown bit of the Configuration register high. While in shutdown, the Temperature register retains the last conversion result and can be read at any time. The ADC is turned off, reducing the device current draw to 30µA (max). The outputs of ALERT and OVERT are latched upon entering shutdown, and the fault queue is held in reset. After coming out of shutdown, the Temperature register continues to read the last converted temperature, until the next conversion result is available. Thermal Considerations The MAX6633/MAX6634/MAX6635 supply current is typically 200µA when the serial interface is inactive. When used to drive high-impedance loads, the devices dissipate negligible power; therefore, the die temperature is essentially the same as the package temperature. The key to accurate temperature monitoring is good thermal contact between the MAX6633/MAX6634/ MAX6635 package and the monitored device or circuit. Heat flows in and out of plastic packages primarily through the leads. Short, wide copper traces leading to the temperature monitor ensure that heat transfers quickly and reliably. The rise in die temperature due to self-heating is given by the following formula: ∆TJ = PDISSIPATION x θJA where P DISSIPATION is the power dissipated by the MAX6633/MAX6634/MAX6635, and θJA is the package’s thermal resistance. The typical thermal resistance is 170°C/W for the 8-pin SO package. To limit the effects of self-heating, minimize the output currents. For example, if the MAX6634/MAX6635 sink 4mA with the maximum ALERT VL specification of 0.8V, an additional 3.2mW of power is dissipated within the IC. This corresponds to a 0.54°C rise in the die temperature. Applications Information Figure 10 shows the MAX6634 used as a simple thermostat to control a heating element. Figure 11 shows the MAX6635 used as a temperature-triggered fan controller. Table 1. Address Selection MAX6633 A3 A2 A1 A0 GND GND GND GND 1000 000 GND GND GND VCC 1000 001 GND GND VCC GND 1000 010 GND GND VCC VCC 1000 011 GND VCC GND GND 1000 100 GND VCC GND VCC 1000 101 GND VCC VCC GND 1000 110 GND VCC VCC VCC 1000 111 VCC GND GND GND 1001 000 VCC GND GND VCC 1001 001 VCC GND VCC GND 1001 010 VCC GND VCC VCC 1001 011 VCC VCC GND GND 1001 100 VCC VCC GND VCC 1001 101 VCC VCC VCC GND 1001 110 VCC VCC VCC VCC 1001 111 MAX6634 A2 A1 A0 ADDRESS GND GND GND 1001 000 GND GND VCC 1001 001 GND VCC GND 1001 010 GND VCC VCC 1001 011 VCC GND GND 1001 100 VCC GND VCC 1001 101 VCC VCC GND 1001 110 VCC VCC 1001 111 A1 A0 ADDRESS GND GND 1001 000 GND VCC 1001 001 VCC GND 1001 010 VCC VCC 1001 011 VCC MAX6635 Chip Information TRANSISTOR COUNT: 12,085 PROCESS: BiCMOS 12 ADDRESS ______________________________________________________________________________________ 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface ADDRESS DESCRIPTION POR STATE 00h Temperature register (READ only) 0000h 01h Configuration-Byte register 00h 02h THYST register 0100h 03h TMAX register 2800h 04h TLOW register 0500h 05h THIGH register 2000h Table 3. Temperature Register D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 MSB (Sign) Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 TMAX THIGH TLOW D15: MSB is the first sign bit. D2, D1, D0: Flag bits for TMAX, THIGH, TLOW. 1LSB = 0.0625°C. Temperature is stored in two’s complement format. Table 4. Configuration Register D7 D6 D5 D4 D3 D2 D1 D0 0 0 SMB Timeout Disable Fault Queue Enable ALERT Polarity OVERT Polarity Comparator or Interrupt Shutdown Power-on default = 0h. D0: 0 = normal operation; 1 = shutdown. D1: 0 = comparator mode; 1 = interrupt mode. D2 to D3: 0 = active low; 1 = active high. D5: 0 = normal SMBus operation; 1 = full I2C compatibility. D7 to D6: Reserved locations, always write zeros. ______________________________________________________________________________________ 13 MAX6633/MAX6634/MAX6635 Table 2. Pointer Register Bit Assignments MAX6633/MAX6634/MAX6635 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface Table 5. Fault Queue Depth D4 NO. OF FAULTS 0 1 (DEFAULT) 1 4 Table 6. Output Code vs. Temperature DIGITAL OUTPUT CODE TEMP. (°C) HEX BINARY MSB LSB +150.0000 0100 1011 0000 0XXX 4B00 +125.0000 0011 1110 1000 0XXX 3E80 +25.0000 0000 1100 1000 0XXX 0C80 +0.0625 0000 0000 0000 1XXX 0008 0.0000 0000 0000 0000 0XXX 0000 -0.0625 1111 1111 1111 1XXX FFF8 -25.0000 1111 0011 0111 0XXX F370 -55.0000 1110 0100 0111 0XXX E470 Table 7. THIGH, TLOW, TMAX, and THYST Registers D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 MSB (Sign) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB 0 0 0 0 0 0 0 D6 to D0: Reads all zeros, cannot be written. 1LSB = 1°C. Power-On Default: THIGH = +64°C (2000h), TLOW = +10°C (0500h), TMAX = +80°C (2008h), THYST = 2°C (0100h). 14 ______________________________________________________________________________________ 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface TOP VIEW SDA 1 SCL 2 8 VCC SDA 1 7 A0 SCL 2 3 6 A1 GND 4 5 A2 SO VCC SDA 1 7 A0 SCL 2 8 VCC 7 A0 3 6 A1 GND 4 5 ALERT MAX6634 MAX6633 A3 8 MAX6635 3 6 A1 GND 4 5 A2 ALERT SO OVERT SO ______________________________________________________________________________________ 15 MAX6633/MAX6634/MAX6635 Pin Configurations 12-Bit Plus Sign Temperature Sensors with SMBus/I2C-Compatible Serial Interface SOICN.EPS MAX6633/MAX6634/MAX6635 Package Information Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.