19-2121; Rev 0; 7/01 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface Features ♦ 12-Bit + Sign, 0.0625°C Resolution ♦ Accuracy ±1°C max (+30°C to +50°C) ±1.6°C max (0°C to +70°C) ±2.5°C max (-20°C to +85°C) ±2.5 typ (+150°C) ♦ Extended Temperature Measurement Range -55°C to +150°C ♦ Low Average Supply Current, 125µA (typ) ♦ Shutdown Mode to Minimize Power Consumption in Portable Applications ♦ Two Programmable Temperature Fault Outputs ♦ Switchable Fault Queue to Eliminate False Tripping in Noisy Environments Ordering Information Applications HVAC Refrigeration PART TEMP. RANGE PIN-PACKAGE MAX6662MSA -55°C to +150°C 8 SO Automotive Test Equipment Pin Configuration Typical Operating Circuit VCC = +3V TO +5.5V TOP VIEW 0.1µF 10kΩ 10kΩ VCC MAX6662 SIO SCLK 8 VCC CS 2 7 NC 3 6 ALERT GND 4 5 OT SIO SYSTEM CONTROLLER ALERT 1 MAX6662 OT HEAT SOURCES SCLK SO CS SPI is a trademark of Motorola, Inc. ________________________________________________________________ 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 MAX6662 General Description The MAX6662 is a 12-bit + sign temperature sensor combined with a programmable overtemperature alarm and a 3-wire (SPI™-compatible) serial interface in a single package. It converts its die temperature into digital values using an internal analog-to-digital converter (ADC). The temperature data is stored in a temperature register as a 13-bit word, which allows 0.0625°C resolution. The temperature data is readable at any time through the serial interface. The operating temperature range is -55°C to +150°C. The MAX6662 provides two programmable watchdog interrupt outputs. ALERT is used for lower temperature warning functions, while OT is used for higher temperature-critical functions, such as power-supply shutdown. The MAX6662 features a shutdown mode that saves power by disabling everything except the serial interface. The temperature sensor is available in an 8-pin SO package. MAX6662 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface ABSOLUTE MAXIMUM RATINGS All Voltages Are Referenced to GND VCC ...........................................................................-0.3V to +6V ALERT, OT................................................................-0.3V to +6V SIO, SCLK, CS............................................-0.3V to (VCC + 0.3V) SIO Current .......................................................-10mA to +50mA Continuous Current into Any Pin (except NC)….................10mA Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW Operating Temperature Range (Note 1) ..........-55°C to +150°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Note 1: The MAX6662 is not recommended to operate above +125°C for an extended period of time. 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 = +3V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C and VCC = +3.3V.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX +30°C ≤ TA ≤ +50°C, VCC = +3.3V -1.0 ±0.4 +1.0 0°C ≤ TA ≤ +70°C, VCC = +3.3V -1.6 ±0.7 +1.6 -20°C ≤ TA ≤ +85°C, VCC = +3.3V -2.5 ±1.0 +2.5 -40°C ≤ TA ≤ +100°C, VCC = +3.3V -3.0 ±1.2 +3.0 -55°C ≤ TA ≤ +125°C, VCC = +3.3V -4.0 ±1.5 +4.0 UNITS TEMPERATURE TO DIGITAL-CONVERTER CHARACTERISTICS Accuracy TA ≤ +150°C, VCC = +3.3V Power-Supply Rejection Ratio ±2.5 PSRR 0.2 Resolution Supply Voltage Range Average Operating Current Peak Operating Current (Note 2) Shutdown Supply Current Power-On-Reset Threshold 3.0 VCC = +5.5V 150 125 °C/V °C 5.5 VCC = +3.0V V µA VCC = +5.5V 300 600 VCC = +3.0V 300 500 VCC = +5.5V 8 22 VCC = +3.0V 4 15 2.0 2.5 µA µA VPOR Power-On-Reset Threshold Hysteresis Conversion Time 0.5 0.0625 VCC °C 90 tCONV Temperature Update Frequency V mV 0.25 s 2 Hz SERIAL INTERFACE (SIO, SCLK, CS, ALERT, OT) Input Low Voltage VIL Input High Voltage VIH Input/Output Leakage Current 2 ILEAK 0.8 V +5 µA 0.7 VCC VIN = GND or VCC -5 3 Input Capacitance Cin Output Low Sink Current IOL ALERT, OT, VOL = 0.6V Output High Voltage VOH ISIO = 1.6mA source Output Low Voltage VOL ISIO = 1.6mA sink V 5 pF mA VCC - 0.4 _______________________________________________________________________________________ V 0.4 V 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface (VCC = +3V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C and VCC = +3.3V.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 2.5 MHz SERIAL INTERFACE TIMING Serial Clock Frequency fSCLK SCLK High Pulse Width tCH 200 ns SCLK Low Pulse Width tCL 200 ns CS High Pulse Width tCSW SCLK Fall to Output Data Valid tDO CS Fall to SCLK Rise tCSS CS Rise to Output Disable 200 100 ns 100 tTR CS to SCLK Hold Time ns CLOAD = 100pF ns CLOAD = 100pF 100 ns tCSH 0 ns SIO to SCLK Setup Time tDS 100 ns SIO to SCLK Hold Time tDH 0 Output Fall Time ns tF 10 ns Note 2: Peak operating current measured during conversion. Typical Operating Characteristics (VCC = +3V, TA = +25°C, unless otherwise noted.) VCC = +3.0V 0 -1 VCC = +5.0V VCC = +3.3V 70 NOTE: DEVICES TRIMMED AT TA = +30°C 200 SAMPLES TA = +30°C 60 50 40 30 20 MAX6662 toc02 80 200 AVERAGE OVER 2 180 SUPPLY CURRENT (µA) 1 90 PERCENTAGE OF SAMPLES (%) 2 SUPPLY CURRENT VS. TEMPERATURE TEMPERATURE ERROR DISTRIBTUTION MAX6662 toc01 TEMPERATURE ERROR (°C) 3 VCC = +5.0V 160 140 VCC = +3.3V 120 -2 VCC = +3.0V 10 -3 MAX6662 toc03 TEMPERATURE ERROR VS. TEMPERATURE 100 0 -50 -30 -10 10 30 50 70 90 110 130 150 -0.45-0.35 -0.25 -0.15 0.05 0.15 0.25 0.35 0.45 TEMPERATURE (°C) TEMPERATURE ERROR (°C) -50 0 50 100 150 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX6662 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VCC = +3V, TA = +25°C, unless otherwise noted.) SHUTDOWN CURRENT VS. TEMPERATURE MAX6662 toc04 12 10 SHUTDOWN CURRENT (µA) MAX6662 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface VCC = +5.0V 8 6 VCC = +3.3V 4 2 VCC = +3.0V 0 -50 0 50 100 150 TEMPERATURE (°C) Pin Description PIN NAME FUNCTION 1 SCLK 2 CS Chip Select Input. Set low to enable the serial interface for data input/output. 3 SIO Serial-Data Input/Output. Bidirectional data input and output for serial interface. 4 GND 5 OT 6 ALERT Serial-Clock Input Ground Overtemperature Output. Open-drain output requires a pullup resistor to VCC. Alert Output. Open-drain output requires a pullup resistor to VCC. 7 NC No Connection. Do not make a connection to this pin. 8 VCC Supply Voltage Input. Bypass to GND with a 0.1µF capacitor as close to VCC as possible. Detailed Description The MAX6662 continuously converts its die temperature into a digital value using its integrated ADC. Temperature data is updated twice a second. The resulting data is readable at any time through the SPIcompatible serial interface. Figure 1 shows the simplified functional diagram of the MAX6662. Its internal current sources force 100µA and 10µA currents through a diode (diode-connected transistor), while the integrating ADC measures the voltage difference. The difference in voltage corresponds to the die temperature. The result is stored in the Temperature register. The control logic unit compares the temperature and the temperature limit settings stored in the registers to determine whether a fault condition has occurred. 4 Temperature Fault Alert The ALERT is an open-drain active-low (default, also programmable active-high) output used to alert the system to temperature faults. ALERT can be programmed to operate in either one of two modes: comparator or interrupt mode. Interrupt Mode In the interrupt mode, the MAX6662 ALERT pin asserts an alarm for an undertemperature (TLOW) fault, as well as for an overtemperature (THIGH) fault. Once either fault has occurred, it remains active indefinitely, regardless of condition. ALERT is unconditionally deasserted (even if Temperature is still out of limits) by reading the temperature register. ALERT only asserts again if the temperature crosses the hysteresis, thereby corresponding to the fault (TLOW or THIGH) that initially set the ALERT. _______________________________________________________________________________________ 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface MAX6662 VCC OT 12 -BIT + SIGN ADC ALERT TEMPERATURE TLOW THIGH TMAX THYST CONFIGURATION SIO SCLK SERIAL INTERFACE CS Figure 1. MAX6662 Simplified Functional Diagram For example: If THIGH is set to 100°C and THYST is set to 20°C, ALERT does not assert until temperature exceeds 100°C. If the temperature is then read through the serial interface, ALERT deasserts. ALERT asserts again when temperature is less than 80°C (Figure 2). Comparator Mode In the comparator mode, ALERT is asserted when temperature exceeds the value in the THIGH register, or is lower than the value in the T LOW register. ALERT deasserts when temperature is less than THIGH - THYST or greater than TLOW + THYST. Reading the registers does not deassert ALERT. For example: If THIGH is set to 100°C and TLOW is set to 80°C, ALERT does not assert until temperature exceeds 100°C, or is below 80°C. Then, ALERT only deasserts if temperature is less than THIGH - THYST or greater than TLOW + THYST. Overtemperature Alert OT operates only in comparator mode. The OT pin is asserted when the temperature exceeds TMAX, and deasserted when the temperature drops below TMAX - THYST. A read operation does not reset OT. OT is an open-drain active-low (default) output, but can be programmed to active-high. THIGH THIGH - THYST TEMPERATURE TLOW + THYST TLOW ALERT * TEMPERATURE READ * * * LAST INTERRUPT MISSED, BUT THRESHOLD STILL CHANGES TO THIGH. Figure 2. Example of ALERT Operation in Interrupt Mode _______________________________________________________________________________________ 5 MAX6662 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface Temperature Fault Queue Serial Interface Protocol The activation of ALERT and OT is subject to the depth of the fault queue. If the Fault Queue bit in the Configuration register is enabled, ALERT or OT does not assert until four consecutive temperature conversions are at fault. For example: If THIGH is set to 100°C, THYST is set to 20°C, ALERT is set to interrupt mode, and fault queue is enabled, ALERT does not assert until four consecutive conversions exceed 100°C. If the temperature is then read through the serial interface, ALERT deasserts. ALERT asserts again when four consecutive conversions are less than 80°C. The serial interface consists of three signal lines: chip select (CS), bidirectional data line (SIO), and serial clock (SCLK). Only the master (external) drives CS and SCLK. Both the master and the MAX6662 drive SIO. When CS is high, the MAX6662 does not respond to any activity on clock and data lines. When CS goes low, a transaction begins. A valid transaction has 24 clock cycles provided from SCLK after CS goes low—no more and no fewer. Any communication with more or fewer than exactly 24 clocks is ignored. Data is clocked in to the MAX6662 at the rising edge of SCLK when the master is writing. Data is clocked out at the falling edge of SCLK when the master is reading. Both the command byte and data word are clocked in (or out) with the most-significant bit (MSB) bit first. The first eight clock cycles are dedicated to the command byte (1 bit per cycle). This command byte is input to the MAX6662 through the SIO. Sixteen cycles of data follow. The 16 cycles of data are either driven by the master or by the MAX6662, depending on the command byte. If the MAX6662 is driving the SIO, it starts driving at the falling edge of the eighth clock up until the rising edge of CS. Data is available on the falling edge of the eighth clock cycle. Figure 3 depicts a valid serial interface transaction and Figure 4 is the serial interface timing diagram. Shutdown Mode The MAX6662 features a programmable shutdown mode. Set the Shutdown bit in the Configuration register to 1 to shut down. In the shutdown mode, everything is disabled except the power-on reset (POR) and the serial interface. In the shutdown mode, information stored in all registers is retained. The Temperature register retains the temperature from the last conversion result. CS 1 2 3 4 5 6 7 8 9 10 23 24 tCSW SCLK CS SIO COMMAND BYTE (8 BITS) DATA WORD (16 BITS) tCSH tCSS SCLK tCH SIO tCL tTR tDS Figure 3. MAX6662 Serial Interface Operation tDO tF tDH Figure 4. Detailed Serial Interface Timing Diagram Table 1. Bit Descriptions of the Configuration Register BIT 6 POR DESCRIPTION 15 to 13 0 Reserved. Writing to these bits is ignored. 12 0 Fault Queue bit. Set to 1 to enable queue. 11 0 ALERT polarity bit. Set to 1 for active-high ALERT output. Default is 0 for the ALERT output active-low. 10 0 OT polarity bit. Set to 1 for active-high OT output. Default is 0 for the OT output active-low. 9 0 Interrupt Mode bit. Set to 1 to enable the interrupt mode. Default is 0 for the comparator mode. 8 0 Shutdown bit. Set to 1 to shut down the MAX6662. 7 to 0 0 Reserved. Writing to these bits is ignored. _______________________________________________________________________________________ 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface COMMAND DESCRIPTION C1h Temperature register read C3h Configuration register read C5h THYST register read C7h TMAX register read C9h TLOW register read MAX6662 Registers CBh THIGH register read The MAX6662 has six registers: Temperature, Configuration, THYST, TMAX, TLOW, and THIGH registers. They are all 16 bits (Figure 5). The Temperature register is read only; all other registers can be read from or written to. 83h Configuration register write 85h THYST register write 87h TMAX register write 89h TLOW register write 8Bh THIGH register write Temperature Register The MSB of the Temperature register is the sign bit. The next 12 bits are temperature data. The digital temperature data for the most recent temperature conversion is TEMPERATURE REGISTER (COMMAND = C1H) 14 Data MSB 13 12 11 10 9 8 7 6 5 4 Label 15 Sign Bit POR State 0 0 0 0 0 0 0 0 0 0 0 0 Label POR State 1 0 3 2 Data TOVER THIGH TLOW LSB Flag Flag Flag 0 0 0 CONFIGURATION REGISTER (COMMAND = C3H FOR READING; COMMAND = 83H FOR WRITING) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 * * * Fault ALERT OT Interrupt Shutdown * * * * * * Queue Polarity Polarity Mode Mode 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 * 0 * 0 0 TEMPERATURE LIMIT REGISTERS (THYST, TMAX, TLOW, THIGH) (TABLE 2) Label 15 Sign 14 Data MSB 13 12 11 POR State 10 9 8 7 Data LSB 6 * 5 * 4 * 3 * 2 * 1 * 0 * ** * Reserved (not used). Writing to this bit is ignored. ** THYST register: 0000 0001 0000 0000b (2°C) ** TMAX register: 0010 1000 0000 0000b (+80°C) ** TLOW register: 0000 0101 0000 0000b (+10°C) ** THIGH register: 0010 0000 0000 0000b (+64°C) Figure 5. Bit Assignment for the MAX6662 Registers _______________________________________________________________________________________ 7 MAX6662 The first bit of the command byte is always high to signify a Start, and the second bit is an R/W bit, high for read and low for write. There are a total of 11 valid commands. The temperature conversion runs continuously and asynchronously from the serial interface. When the Temperature register is read, any conversion in progress is aborted and the data output is from the previous conversion. A new conversion is started each time the serial interface is accessed. Table 2. Command Codes for the Temperature Limit Registers MAX6662 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface Table 3. Output Code vs. Temperature TEMPERATURE (°C) BINARY CODE +150.0000 0100 1011 0000 0xxx +125.0000 0011 1110 1000 0xxx +25.0000 0000 1100 1000 0xxx +0.0625 0000 0000 0000 1xxx 0.0000 0000 0000 0000 0xxx -0.0625 1111 1111 1111 1xxx -25.0000 1111 0011 0111 0xxx -55.0000 1111 1100 0111 0xxx stored in the Temperature register and is in °C, using a two’s-complement format with 1LSB corresponding to 0.0625°C (Table 3). The three least-significant bits (LSBs) are temperature status (flag) bits. The Temperature register is read only. Set the command byte to C1h for reading the Temperature register. Configuration Register The Configuration register uses only 5 bits, bits 8 to 12. Table 1 describes its function. Bit 8 is the shutdown bit and should be set to 1 to shut down the entire MAX6662 except the serial interface and POR. Bit 12 is the fault queue bit. When the Fault Queue bit is 1, the ALERT and OT outputs are asserted if four consecutive temperature faults occurred. The Configuration register can be read or written to. Writing to unused bits is ignored. Set the command byte to C3h for reading from this register; set the command byte to 83h for writing to this register. The MAX6662 supply current is typically 125µA when the serial interface is active. When driving 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 MAX6662 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 MAX6662, 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 MAX6662 sinks 4mA with the maximum ALERT voltage 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. Chip Information TRANSISTOR COUNT: Bipolar: 182 MOS: 10177 PROCESS: BiCMOS Temperature-Limit Registers The High-Temperature (T HIGH ), Low-Temperature (TLOW), and the Hysteresis (THYST) registers set the temperature limit for triggering the ALERT (Figure 1). The Maximum-Temperature (TMAX) and Hysteresis registers set the temperature threshold for the OT output. These temperature-limit registers use the 9MSB bits (8 bits + sign) for setting temperature values in two’s complement format with 1°C resolution. The 7LSBs are ignored. These registers can be read or written to. Table 2 shows the command bytes for reading and writing to these registers. Applications Information 8 _______________________________________________________________________________________ 12-Bit + Sign Temperature Sensor with SPI-Compatible Serial Interface SOICN.EPS 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX6662 Package Information