19-2047; Rev 1; 7/01 12-Bit + Sign Digital Temperature Sensors with Serial Interface The MAX6629–MAX6632 are local digital temperature sensors with an SPI™-compatible serial interface. The temperature is converted to a 12-bit + sign word with a resolution of 0.0625°C/LSB. An extended temperature range provides useful readings up to +150°C. These sensors are 3-wire serial interface SPI compatible, allowing the MAX6629–MAX6632 to be readily connected to a variety of microcontrollers (µCs). The MAX6629–MAX6632 are read-only devices, simplifying their use in systems where only temperature data is required. All four digital temperature sensors require very little supply current, making them ideal for portable systems. The MAX6631/MAX6632 perform a temperature-to-digital conversion once every 8s and require minimal average supply current, 32µA (typ). The MAX6629/ MAX6630 perform a conversion once every 0.5s and require only 200µA (typ) supply current. Any of these temperature sensors can perform conversions more often—up to approximately four conversions per second by reading the conversion results more often. Features ♦ Low Power Consumption 32µA typ (MAX6631/MAX6632) 200µA typ (MAX6629/MAX6630) ♦ 12-Bit + Sign Resolution with 0.0625°C/LSB ♦ Accuracy ±1°C (max) from 0°C to +70°C ±2.3°C (max) from -20°C to +100°C ±3.2°C (max) from -40°C to +125°C ±6.5°C (max) at +150°C ♦ +150°C Extended Temperature Range ♦ SPI-Compatible Serial Interface ♦ +3.0V to +5.5V Supply Range ♦ 6-Pin SOT23 Package Ordering Information Applications Cellular Automotive Hard Disk Drive Industrial Control Systems HVAC SPI is a trademark of Motorola, Inc. PART TEMP. RANGE PINPACKAGE TOP MARK MAX6629MUT-T -55°C to +150°C 6 SOT23-6 AAPM MAX6630MUT-T -55°C to +150°C 6 SOT23-6 AAPN MAX6631MUT-T -55°C to +150°C 6 SOT23-6 AAPO MAX6632MUT-T -55°C to +150°C 6 SOT23-6 AAPP Typical Application Circuit +3V TO +5.5V VCC Pin Configurations MAX6629 MAX6630 MAX6631 MAX6632 0.1µF TOP VIEW SO N.C. 1 µC CS GND SCK GND 2 MAX6629 MAX6631 VCC 3 SOT23 6 SO GND 1 5 CS N.C. 2 4 SCK VCC 3 MAX6630 MAX6632 6 SO 5 CS 4 SCK SOT23 ________________________________________________________________ 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 MAX6629–MAX6632 General Description MAX6629–MAX6632 12-Bit + Sign Digital Temperature Sensors with Serial Interface ABSOLUTE MAXIMUM RATINGS All Voltages Referenced to GND VCC ...........................................................................-0.3V, +6.0V SO, SCK, CS ....................................................-0.3V, VCC + 0.3V SO .......................................................................-1mA to +50mA Current into Any Pin ............................................................10mA Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 9.10mW/°C above +70°C)..........727mW Junction Temperature ......................................................+150°C Operating Temperature Range (Note 1) ...........-55°C to +150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature .............................................................Note 2 Note 1: It is not recommended to operate the device above +125°C for extended periods of time. Note 2: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board-level solder attach and rework. This limit permits only the use of the solder profiles recommended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection Reflow. Preheating is required. Hand or wave soldering is not allowed. 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 at VCC = +3.3V and TA = +25°C.) (Notes 3 and 4) PARAMETER SYMBOL CONDITIONS MIN TYP MAX TA = room temp, VCC = +3.3V -0.8 ±0.2 +0.8 0°C ≤ TA ≤ +70°C, VCC = +3.3V -1.0 ±0.2 +1.0 -20°C ≤ TA ≤ +85°C, VCC = +3.3V -1.6 +0.3 +1.6 -20°C ≤ TA ≤ +100°C, VCC = +3.3V -2.3 +0.5 +2.3 UNITS TEMPERATURE Accuracy Power-Supply Sensitivity -40°C ≤ TA ≤ +125°C, VCC = +3.3V -3.2 +0.8 +3.2 TA ≥ -55°C, VCC = +3.3V -1.0 +1.5 +3.5 TA = +150°C, VCC = +3.3V -5.0 +1.5 +6.5 0.2 0.6 PSS Resolution Time Between Conversion Starts Conversion Time 0.0625 tSAMPLE °C °C/V °C MAX6629, MAX6630, CS high 0.37 0.5 0.65 MAX6631, MAX6632, CS high 5.9 8 10.5 180 250 320 ms 5.5 V tCONV s POWER SUPPLY Supply Voltage Range VCC ISD Supply Current, SCK Idle Average Operating Current Power-On Reset (POR) Threshold 2 3.0 Shutdown (Note 4), VCC = +0.8V IIDLE ADC idle (Figure 2), CS = low ICONV ICC 5 6 20 ADC converting (Figure 2) 360 650 MAX6629, MAX6630 200 400 MAX6631, MAX6632 32 50 VCC falling 1.6 _______________________________________________________________________________________ µA µA V 12-Bit + Sign Digital Temperature Sensors with Serial Interface (VCC = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Notes 3 and 4) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.3 x VCC V LOGIC INPUTS (CS, SCK) Logic Input Low Voltage VIL Logic Input High Voltage VIH Input Leakage Current ILEAK 0.7 x VCC V ±1 VIN = GND or +5.5V ±5 µA 0.4 V LOGIC OUTPUTS (SO) Output Low Voltage VOL ISINK = 1.6mA Output High Voltage VOH ISOURCE = 1.6mA VCC - 0.4 V TIMING CHARACTERISTICS (Notes 5 and 6) Serial Clock Frequency fSCL SCK Pulse Width High tCH 100 5 ns SCK Pulse Width Low tCL 100 ns CS Fall to SCK Rise tCSS CLOAD = 10pF CS Fall to Output Enable tDV CLOAD = 10pF 80 ns CS Rise to Output Disable tTR CLOAD = 10pF 50 ns SCK Fall to Output Data Valid tDO CLOAD = 10pF 80 ns 80 MHz ns Note 3: Tested at a single temperature. Specifications over temperature are guaranteed by design. Note 4: MAX6629–MAX6632 are not specifically equipped with a shutdown function. Their low supply current permits powering them from the output of a logic gate. This specification is given to ensure that the MAX6629–MAX6632 do not draw excessive currents at low supply voltages, ensuring reliable operation from a gate output. Note 5: Timing characteristics are guaranteed by design and are not production tested. Note 6: CLOAD = total capacitance of one bus line in picofarads. _______________________________________________________________________________________ 3 MAX6629–MAX6632 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) POWER-ON RESET (POR) THRESHOLD vs.TEMPERATURE VCC = +5.0V 2.4 300 VCC = +3.3V 250 VCC = +3.6V VCC = +3.0V 200 150 3 2.2 2 TEMPERATURE ERROR (°C) 350 2.6 MAX6629-32 toc02 VCC = +4.5V POWER-ON RESET THRESHOLD (V) VCC = +5.5V MAX6629-32 toc01 400 TEMPERATURE ERROR vs. TEMPERATURE 2.0 1.8 1.6 1.4 1.2 -55 -30 -5 20 45 70 95 -5 20 45 70 95 120 145 MAX6629 -55 -30 -5 45 70 95 120 145 TEMPERATURE (°C) MAX6629-32 toc05 MAX6629-32 toc04 VIN = SQUARE WAVE APPLIED TO VCC WITH NO 0.1µF CAPACITOR 20 RESPONSE TO THERMAL SHOCK 125 100 8 TEMPERATURE (°C) TEMPERATURE ERROR (°C) -2 TEMPERATURE (°C) TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY 10 -1 -4 -55 -30 120 145 TEMPERATURE (°C) 12 0 -3 0.6 100 1 1.0 0.8 MAX6629 MAX6629-32 toc03 OPERATING SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT (µA) MAX6629–MAX6632 12-Bit + Sign Digital Temperature Sensors with Serial Interface 6 VIN = 250mVp-p 4 75 50 25 2 0 0 10 100 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) -2 0 2 4 6 8 10 12 14 TIME (s) Pin Description PIN 4 NAME FUNCTION MAX6629 MAX6631 MAX6630 MAX6632 1 2 N.C. No Connect. Connect to ground plane for better thermal performance to the PC board. 2 1 GND Ground 3 3 VCC Supply Voltage Input. Bypass VCC to GND with a 0.1µF capacitor. VCC can also be powered from a logic output as long as the voltage level is greater than 3.0V and the logic output is not noisy. Setting the logic output low provides a hardware shutdown mode. 4 4 SCK Serial Clock Input 5 5 CS Chip-Select Input. Enables the interface. A rising edge off CS initiates the next conversion. Pulling CS low initiates an idle state. 6 6 SO Serial Data Output _______________________________________________________________________________________ 12-Bit + Sign Digital Temperature Sensors with Serial Interface The MAX6629–MAX6632 are local digital temperature sensors with a serial bus. The MAX6629–MAX6632 are typically interfaced to a µC in temperature sensing and control applications. The MAX6629–MAX6632 convert temperature to a 12-bit + sign word with a 0.0625°C LSB. The data is communicated through a simple serial interface with a CS (Chip Select) line, SO (Data) line, and SCK (Clock) line. This interface can be directly connected to, and is fully compatible with, SPI interfaces. This interface can also be connected to virtually any processor, which has at least three general-purpose input/output (GPIO) lines available to implement software “bit banging.” The high resolution of the MAX6629–MAX6632 makes them especially useful in thermal control loops, HVAC systems, or in any system where quick anticipation of temperature trends is useful. The MAX6629–MAX6632 can produce temperature data in excess of +150°C, although they are specified for a maximum operating temperature of +150°C. This extended temperature range especially makes it useful in automotive underhood applications. The low power consumption is also ideal in battery-operated and portable applications. The MAX6631/MAX6632 are optimized for minimum power consumption with their 8s conversions. The MAX6629/MAX6630 provide faster conversions, 0.5s, at the expense of power consumption. The low quiescent supply current enables the device to be powered from a logic line or the output of a gate where the high level exceeds 3V, as shown in Figure 1. While the MAX6629–MAX6632 are not specifically equipped with a software shutdown mode, the hardware shutdown can easily be implemented by setting the gate output to low. Pulling CS low without a clock also puts the device in idle mode. Take care to ensure that the logic output MAX6629 MAX6630 0.25s ADC CONVERSION TIME LOGIC LINE WHERE VLOGIC > 3V VCC MAX6629 MAX6630 MAX6631 MAX6632 SO SCK CS GND Figure 1. Powering the Sensor from a Logic Gate is not noisy, as excessive noise on VCC can affect temperature measurement accuracy. ADC Conversion Sequence The MAX6629–MAX6632 continuously convert temperature to digital data. Setting CS low stops any conversion in progress, places the device in idle mode, and makes data available for reading. Setting CS high starts a new conversion. CS must remain high for at least 0.3s to allow for the conversion to be completed. Figure 2 shows the timing relationship between conversion time and conversion rate. SPI Digital Interface The MAX6629–MAX6632 are compatible with SPI serial-interface standards (Figure 3) and are designed to be read-only devices. CS’s rising edge always starts a new conversion and resets the interface. CS must stay high for a minimum of 300ms to allow the conversion to MAX6629 MAX6630 CONVERSION PERIOD 0.5s MAX6631 MAX6632 0.25s ADC CONVERSION TIME MAX6631 MAX6632 CONVERSION PERIOD 8s Figure 2. Conversion Time and Rate Relationships _______________________________________________________________________________________ 5 MAX6629–MAX6632 Detailed Description MAX6629–MAX6632 12-Bit + Sign Digital Temperature Sensors with Serial Interface tCSS CS SCK tDV tDO tTR SO D15 D3 D2 D1 D0 Figure 3. SPI Timing Diagram Table 1. Data Output Format D15 D14 Sign MSB Data D13 D12 D11 D10 D9 D8 Table 2. Temperature Data Format (Two’s Complement) TEMPERATURE (°C) DIGITAL OUTPUT (BINARY) D15–D3 D2 D1, D0 150 0,1001,0110,0000 0 XX 125 0,0111,1101,0000 0 XX 25 0,0001,1001,0000 0 XX 0.0625 0,0000,0000,0001 0 XX 0 0,0000,0000,0000 0 XX -0.0625 1,1111,1111,1111 0 XX -25 1,1110,0111,0000 0 XX -55 1,1100,1001,0000 0 XX D7 D6 D5 D4 D3 D2 D1 D0 LSB Data Low High-Z High-Z undefined and are always in high-impedance mode (Table 1). The power-up state for SO is high impedance. Figure 3 shows the detailed serial timing specifications for the SPI port. The temperature data format is in two's complement format (Table 2). Power Shutdown Mode The MAX6629–MAX6632 do not have a built-in power software shutdown mode. However, a power shutdown mode is easily implemented utilizing an unused logic gate. A typical CMOS or TTL logic output has enough drive capability to serve as the power source if its output voltage level exceeds 3V, as shown in Figure 1. Drive the logic output low to provide a hardware shutdown mode. Idle Mode finish. CS’s falling edge stops any conversion in progress, and data is latched into the shift register. Then the data clocks out at SO on SCK’s falling edge with the sign bit (D15) first, followed by the MSB. Data is sent in one 16-bit word, and CS must remain low until all 16 bits are transferred. If CS goes high in the middle of a transmission, it is necessary to wait the conversion time (less than 300ms) before attempting a new read. The serial data is composed of 12 + 1 data bits (D15–D3) and 3 trailing bits (D2–D0). D2 is always low, serving as the confirmation bit that the device has been communicated with. The last 2 bits, D0 and D1, are 6 The MAX6629–MAX6632 can be put into idle mode by pulling CS low. Data can be clocked out when the device is in idle mode. Power-On Reset (POR) The POR supply voltage of the MAX6629–MAX6632 is typically 1.6V. Below this supply voltage the interface is inactive and the data register is set to the POR state, 0°C. When power is first applied and VCC rises above 1.6V (typ), the device starts to convert, although temperature reading is not recommended at VCC levels below 3.0V. _______________________________________________________________________________________ 12-Bit + Sign Digital Temperature Sensors with Serial Interface Functional Block Diagram Thermal Considerations The key to accurate temperature monitoring is good thermal contact between the MAX6629–MAX6632 package and the object being monitored. In some applications, the 6-pin SOT23 package is small enough to fit underneath a socketed µP, allowing the device to monitor the µP’s temperature directly. Accurate temperature monitoring depends on the thermal resistance between the object being monitored and the MAX6629–MAX6632 die. Heat flows in and out of plastic packages primarily through the leads. If the sensor is intended to measure the temperature of a heat-generating component on the circuit board, it should be mounted as close as possible to that component and should share supply and ground traces (if they are not noisy) with that component where possible. This maximizes the heat transfer from the component to the sensor. The MAX6629/MAX6630 supply current is typically 200µA, and the MAX6631/MAX6632 supply current is typically 32µA. When used to drive high-impedance loads, the device dissipates negligible power. Therefore, the die temperature is essentially the same as the package temperature. VOLTAGE REFERENCE MAX6629 MAX6630 MAX6631 MAX6632 TEMPERATURE SENSOR 12-BIT + SIGN ∑∆ ADC SPI-COMPATIBLE INTERFACE CS SCK SO Chip Information TRANSISTOR COUNT: 6475 PROCESS: BiCMOS 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 MAX6629–MAX6632, and θJA is the package’s thermal resistance. The typical thermal resistance is +110°C/W for the 6-pin SOT23 package. To limit the effects of self-heating, minimize the output currents. For example, if the MAX6629–MAX6632 sink 1mA, the output voltage is guaranteed to be less than 0.4V. Therefore, an additional 0.4mW of power is dissipated within the IC. This corresponds to a 0.044°C shift in the die temperature in the 6-pin SOT23. _______________________________________________________________________________________ 7 MAX6629–MAX6632 Applications Information MAX6629–MAX6632 12-Bit + Sign Digital Temperature Sensors with Serial Interface 6LSOT.EPS 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. 8 _____________________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.