19-2226; Rev 1; 7/04 KIT ATION EVALU E L B AVAILA Temperature Sensor and System Monitor in a 10-Pin µMAX The MAX6683 system supervisor monitors multiple power-supply voltages, including its own, and also features an on-board temperature sensor. The MAX6683 converts voltages to an 8-bit code and temperatures to an 11-bit (10-bit-plus-sign) code using an analog-todigital converter (ADC). A multiplexer automatically sequences through the voltage and temperature measurements. The digitized signals are then stored in registers and compared to the over/underthreshold limits programmed over the SMBus™/I 2C™-compatible 2wire serial interface. When a temperature measurement exceeds the programmed threshold, or when an input voltage falls outside the programmed voltage limits, the MAX6683 generates a latched interrupt output ALERT. Three interrupt modes are available for temperature excursions. These are default mode, one-time interrupt mode, and comparator mode. The ALERT output is cleared, except for temperature interrupts generated in comparator mode, by reading the Interrupt Status register (Table 5). The ALERT output can also be masked by writing to the appropriate bits in the Interrupt Mask register (Table 6) or by setting bit 1 of the Configuration register (Table 4) to zero. The MAX6683 SMBus/I2Ccompatible interface also responds to the SMB alert response address. Applications Features ♦ Monitors Local Temperature ♦ Monitors Three External Voltages (1.8V, 2.5V, 5V Nominal) ♦ Monitors VCC (3.3V Nominal) ♦ User-Programmable Voltage and Temperature Thresholds ♦ Alert Function with Ability to Respond to SMB Alert Response Address ♦ +2.7V to +5.5V Supply Range ♦ -40°C to +125°C Temperature Range ♦ 60Hz or 50Hz Line-Frequency Rejection ♦ Tiny 10-Pin µMAX Package ♦ MAX6683EVKIT Available Ordering Information PART TEMP RANGE MAX6683AUB PIN-PACKAGE -40°C to +125°C 10 µMAX Workstations Servers Networking Telecommunications Typical Application Circuit 1.8V Pin Configuration TOP VIEW VCC = +3.3V CPU 1.8VIN 1 0.1μF 2.5VIN 10kΩ TO 1.8V TO 2.5V TO 5V 1.8VIN 2.5VIN 5VIN VCC SCL SDA N.C. ADD GND ALERT I2C/SMBus CONTROLLER 10 VCC 2 MAX6683 9 SCL 5VIN 3 8 SDA N.C. 4 7 ADD GND 5 6 ALERT SMBus is a trademark of Intel Corp. I2C is a trademark of Philips Corp. ________________________________________________________________ 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 MAX6683 General Description MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX ABSOLUTE MAXIMUM RATINGS All Voltages Referenced to GND All Pins...................................................................-0.3V to +6.0V SDA, ALERT Current ...........................................-1mA to +50mA Continuous Power Dissipation (TA = +70°C) 10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW Junction Temperature ......................................................+150°C Operating Temperature Range .........................-40°C to +125°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 (TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V 200 500 POWER SUPPLY Supply Voltage Supply Current VCC 2.7 ICC Operating ISD Shutdown mode, interface inactive Power-On Reset (POR) Voltage 10 VCC, rising or falling edge 2 µA V TEMPERATURE TA = +25°C, VCC = +3.3V Accuracy Resolution Supply Sensitivity ±3 0°C ≤ TA ≤ +125°C, VCC = +3.3V ±4 -40°C ≤ TA ≤ +125°C, VCC = +3.3V ±6 Read word mode 0.125 PSS 0.7 °C °C ±1.5 °C/V ±1.5 % ADC CHARACTERISTICS Total Unadjusted Error TUE VIN > 10LSBs Differential Nonlinearity DNL VIN > 10LSBs Supply Sensitivity PSS Input Resistance RIN Total Monitoring Cycle Time tc ±1 ±1 1.8VIN, 2.5VIN, 5VIN 100 (Note 1) LSB LSB/V 150 200 kΩ 200 300 ms 0.8 V SCL, SDA, ADD Logic Input Low Voltage VIL Logic Input High Voltage VIH Input Leakage Current Output Low Voltage VCC ≤ 3.6V 2.0 VCC > 3.6V 2.6 V ILEAK VIN = 0 or 5V ±1 µA VOL ISINK = 3mA 400 mV ISINK = 1.2mA, VCC > 2.7V 0.3 ISINK = 3.2mA, VCC > 4.5V 0.4 ALERT Output Low Voltage 2 VOLA _______________________________________________________________________________________ V Temperature Sensor and System Monitor in a 10-Pin µMAX (TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 400 kHz TIMING (Figures 3 and 4) Serial Clock Frequency fSCL 0 Bus Free Time Between Stop and Start TBUF 1.3 µs Start Condition Hold Time tHD:STA 0.6 µs Stop Condition Hold Time tSU:STO 0.6 µs Clock Low Time TLOW 1.3 µs Clock High Time THIGH 0.6 µs Data Setup Time tSU:DAT 100 ns Data Hold Time tHD:DAT (Note 2) 0 0.9 µs (Note 3) 20 + 0.1Cb ns tR (Note 3) 300 ns Receive SCL/SDA Minimum Fall Time tF (Note 3) 20 + 0.1Cb ns Receive SCL/SDA Maximum Fall Time tF (Note 3) 300 ns Transmit SDA Fall Time tF Cb = 400pF, ISINK = 3mA Pulse Width of Spike Suppressed tSP (Note 4) Receive SCL/SDA Minimum Rise Time tR Receive SCL/SDA Maximum Rise Time 20 + 0.1Cb 300 50 ns ns Note 1: Total monitoring time includes temperature conversion and four analog input voltage conversions. Note 2: A master device must provide at least a 300ns hold time for the SDA signal, referred to VIL of the SCL signal, to bridge the undefined region of SCL’s falling edge. Note 3: Cb = total capacitance of one bus line in pF. Rise and fall times are measured between 0.3 ✕ VCC to 0.7 ✕ VCC. Note 4: Input filters on SDA, SCL, and ADD suppress noise spikes <50ns. _______________________________________________________________________________________ 3 MAX6683 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = +3.3V, ADD = GND, TA = +25°C, unless otherwise noted.) C 200 D E 150 A: TA = +125°C B: TA = +85°C C: TA = +25°C D: TA = 0°C E: TA = -40°C 100 50 0 2.5 3.0 3.5 400 375 350 325 300 3 275 4.5 5.0 100 10 -2 TA = -40°C 3.0 4 3 2 1 MAX6683 toc05 5 MAX6683 toc04 VCC = +5V BYPASS CAP REMOVED 200mVp-p 3.5 4 3 2 1 0 -1 -2 -3 -4 0 -5 1 10 100 1k SUPPLY NOISE FREQUENCY (Hz) 4 10k -50 -25 4.0 4.5 SUPPLY VOLTAGE (V) TEMPERATURE ERROR vs. TEMPERATURE TEMPERATURE ERROR (°C) TEMPERATURE ERROR (°C) -1 2.5 1000 TEMPERATURE ERROR vs. SUPPLY NOISE FREQUENCY 5 TA = 0°C 0 CLOCK FREQUENCY (kHz) SUPPLY VOLTAGE (V) 6 TA = +85°C 1 -4 1 5.5 2 -3 250 4.0 MAX6683 toc03 425 SUPPLY CURRENT (μA) A B VCC = +5V SCL = 3Vp-p TEMPERATURE ERROR (°C) 300 4 MAX6683 toc02 INTERFACE INACTIVE 250 450 MAX6683 toc01 350 TEMPERATURE ERROR vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. SCL CLOCK FREQUENCY SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (μA) MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX 0 25 50 75 100 125 TEMPERATURE (°C) _______________________________________________________________________________________ 5.0 5.5 Temperature Sensor and System Monitor in a 10-Pin µMAX PIN NAME FUNCTION 1 1.8VIN Analog Input. Monitors 1.8V nominal supply. 2 2.5VIN Analog Input. Monitors 2.5V nominal supply. 3 5VIN Analog Input. Monitors 5V nominal supply. 4 N.C. No Connect. Not internally connected. Connect to GND to improve thermal conductivity. 5 GND Ground 6 ALERT 7 ADD SMBus/I2C-Compatible Address Select Input. ADD is sampled at the beginning of each SMBus/I2C transaction, and the 2LSBs of the Slave Address register are detemined by ADD’s connection to GND, SDA, SCL, or VCC. 8 SDA SMBus/I2C-Compatible Serial Data Interface 9 SCL SMBus/I2C-Compatible Clock Input 10 VCC Supply Voltage Input, +2.7V to +5.5V. Also serves as a voltage monitor input. Bypass VCC to GND with a 0.1µF capacitor. SMBus Alert (Interrupt) Output, Open Drain. Alerts the master that a temperature or voltage limit has been violated. Detailed Description The MAX6683 is a voltage and temperature monitor designed to communicate through an SMBus/I2C interface with an external microcontroller (µC). A µC with no built-in I2C or SMBus capabilities can generate SMBus serial commands by “bit-banging” general-purpose input-output (GPIO) pins. The MAX6683 can monitor external supply voltages of typically 1.8V, 2.5V, 5V, as well as its own supply voltage and temperature. This makes it ideal for supervisor and thermal management applications in telecommunications, desktop and notebook computers, workstations, and networking equipment. Voltage inputs are converted to an 8-bit code and temperature is converted to an 11-bit code. The high-order 8 bits of the temperature conversion can be read using a read byte operation through the I2C interface. The full 11-bit temperature conversion is read using a read word operation and disregarding the lower 5 bits of the low byte. By setting bit 5 of the Configuration Register to 1, the temperature conversion can be reduced to 9 bits with a four-fold reduction in conversion time. In this case, the lower 7 bits of the low byte should be disregarded; 8bit temperature data has a resolution of 1°C/LSB, while 11-bit temperature data has a resolution of 0.125°C/ LSB. Setting bit 5 of the Configuration Register to 1 reduces the monitoring cycle time by a factor of 4. In this case, a read word operation for temperature data yields a 9-bit code in which the lower 7 bits of the low byte should be disregarded. The LSB of the 9-bit temperature data has a value of 0.5°C. Each input voltage is scaled down by an on-chip resistive voltage-divider so that its output, at the nominal input voltage, is 3/4 of the ADC’s full-scale range, or a decimal count of 192 (Table 3). Input voltages other than the nominal values may be used; ensure that they fall within the usable ranges of pins to which they are applied. Attenuate voltages greater than 6V with an external resistive voltage-divider. Writing a 1 to bit 0 of the Configuration Register starts the monitoring function. The device performs a sequential sampling of all the inputs, starting with the internal temperature sensor and continuing with 2.5VIN, 1.8VIN, 5VIN, and VCC. If the master terminates the conversion, the sequential sampling does not stop until the sampling cycle is completed and the results are stored. When it starts again, it always starts with the temperature measurement. An interrupt signal is generated when a temperature measurement goes above the hot limit or when a voltage measurement is either above the high limit or below the low limit. This causes the open-drain output ALERT to go to the active-low state and set each corresponding interrupt status bit (bits 0 through 4) to 1 (Table 5). The interrupt is cleared by reading the Interrupt Status Register except for temperature interrupts generated in comparator mode. Reading the Interrupt Status Register also clears the register itself, except for temperature interrupt bits set in comparator mode. _______________________________________________________________________________________ 5 MAX6683 Pin Description MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX Table 1. Register Map ADDRESS READ/WRITE POWER-ON DEFAULT 20h R — 21h R — Data register for 1.8VIN measurement 22h R — Data register for 5VIN measurement 23h R — Data register for VCC measurement Data register for temperature measurement 27h R — 2Bh R/W 1101 0011 (1.1 × 2.5V) High limit for 2.5VIN 2Ch R/W 1010 1101 (0.9 × 2.5V) Low limit for 2.5VIN 2Dh R/W 1101 0011 (1.1 × 1.8V) High limit for 1.8VIN 2Eh R/W 1010 1101 (0.9 × 1.8V) Low limit for 1.8VIN 2Fh R/W 1101 0011 (1.1 × 5V) High limit for 5VIN 30h R/W 1010 1101 (0.9 × 5V) Low limit for 5VIN 31h R/W 1101 0011 (1.1 × 3.3V) High limit for VCC 32h R/W 1010 1101 (0.9 × 3.3V) Low limit for VCC 39h R/W 0101 0000 (+80°C) Hot temperature limit 3Ah R/W 0100 0001 (+65°C) Hot temperature hysteresis 40h R/W 0000 1000 Configuration Register 41h R 0000 0000 Interrupt Status Register 43h R/W 0000 0000 Interrupt Mask Register 48h R/W 0010 1XXY Device Address Register. The values of XX are dependent on the status of the ADD pin. Power-On Default ADD Connection 0010 100Y To GND 0010 101Y To VCC 0010 110Y To SDA 0010 111Y To SCL Y (bit 0) is the SMBus read/write bit. When the 7-bit chip address is read back from the Serial Address Register, an 8-bit word is presented with a zero in bit 0 (Y). 4Bh R/W 0000 0000 Temperature Configuration Register Unless the fault is removed, the ALERT output only remains cleared until the end of the next conversion cycle where it is again asserted. The ALERT output can also be masked by writing to the appropriate bits in the Interrupt Mask Register (Table 6) or by setting bit 1 of the Configuration Register (Table 4) to zero. The 2-wire serial interface accepts both I2C and standard SMBus Write Byte, Read Byte, Read Word, Send Byte, and Receive Byte commands to program the alarm thresholds and to read voltage and temperature data. Voltage data is scaled so that when the nominal voltage is present at an input (e.g., 1.8V for the 1.8VIN input), the conversion result is equal to 3/4 of the ADC full-scale range or a decimal count of 192 (Table 1). 6 DESCRIPTION Data register for 2.5 VIN measurement When using the Read Byte command, the temperature data format is 7 bits plus sign with the LSB equal to 1°C, in two's complement format. When using the Read Word command, the temperature data format is 10 bits plus sign, with the LSB equal to 0.125°C, in two’s complement format. See Table 2 for the temperature data format. The MAX6683 has only one address input, ADD. Connect ADD to GND, VCC , SDA, or SCL to select one of four different address codes. Whenever an SMBus/I 2C transaction is initiated, the 2LSBs of the Slave Address Register are determined by connection, setting the chip address to one of four possible values. In addition, an address code can also be directly writ- _______________________________________________________________________________________ Temperature Sensor and System Monitor in a 10-Pin µMAX HIGH BYTE TEMPERATURE (°C) DIGITAL OUTPUT (BINARY) DIGITAL OUTPUT (HEX) +125 0111 1101 7D +25 0001 1001 19 Low-Power Shutdown Mode +1 0000 0001 01 Setting bit 0 in the Configuration Register to zero stops the monitoring loop and puts the MAX6683 into lowpower shutdown mode. In this mode, the SMBus/I2C interface remains active, and the supply current drops to 10µA or less. 0 0000 0000 00 -1 1111 1111 FF -25 1110 0111 E7 -40 1101 1000 D8 Power-On Reset LOW BYTE 0.875 1110 0000 D0 0.125 0010 0000 20 The MAX6683 POR supply voltage is typically 2V. Below this supply voltage, all registers are reset, the device is put into shutdown mode, and the SMBus/I2C interface is inactive. Alarm Threshold Registers ten to the Serial Address Register. This code overwrites the code set by connection of the ADD pin, until the MAX6683 is taken through a POR cycle. Two registers, a hot temperature limit (THOT) at 39h and a hot temperature hysteresis (T HYST ) at 3Ah, store alarm threshold data (Table 1). If a measured temperature exceeds the value of THOT, an ALERT is asserted. Alerts are cleared and reasserted depending on the interrupt mode selected in the Temperature Configuration Register (see ALERT Interrupts). ADC and Multiplexer The ADC integrates over a 66ms period, an integral multiple of the line period with excellent noise rejection. The internal oscillator is trimmed to produce a 66ms conversion time for temperature and 33ms for each Table 3. Voltage Data Format ADC OUTPUT CODE INPUT VOLTAGE AT 1.8VIN INPUT VOLTAGE AT 2.5VIN INPUT VOLTAGE AT 5VIN VCC = +3.3V LSB weight 9.375mV (1.8V/192) 13mV (2.5V/192) 26mV (5V/192) 17.2mV (3.3V/192) 0 < 9.375mV < 13mV < 26mV — 1 9.375mV to 18.75mV 13mV to 26mV 26mV to 52mV — 2 18.75mV to 28.125mV 26mV to 39mV 52mV to 78mV — — — — — — 64 (1/4 scale) 600mV to 609.4mV 833mV to 846mV 1.664V to 1.692V — — — — — — 128 (1/2 scale) 1.2V to 1.2094V 1.667V to 1.680V 3.330V to 3.560V — — — — — — 192 (3/4 scale) 1.8V to 1.737V 2.5V to 2.513V 5V to 5.026V 3.3V to 3.317V — — — — — 253 2.372V to 2.381V 3.294V to 3.307V 6.566V to 6.640V 4.348V to 4.366V 254 2.381V to 2.391V 3.572V to 3.586V 6.615V to 6.640V 4.366V to 4.383V 255 = 2.391V = 3.586V = 6.640V = 4.383V _______________________________________________________________________________________ 7 MAX6683 voltage. This is equivalent to 4 and 2 cycles of 60Hz, respectively, and provides protection against noise pickup from the main supply. The internal oscillator frequency can be changed to provide the same protection against 50Hz by setting bit 7 in the Configuration Register to 1 (Table 4). The multiplexer automatically sequences through the inputs, measuring voltages and temperature. Table 2. Temperature Data Format (Two's Complement) MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX Table 4. Configuration Register (Address 40h, Power-On Default = 08h) BIT NAME READ/WRITE DESCRIPTION 0 Start/Stop R/W This bit controls the monitoring loop. Setting the bit to zero stops the monitoring loop and puts the device into shutdown mode. The I2C/SMBus interface is still active during the shutdown mode. Setting the bit to 1 starts the monitoring cycle. All high/low limits should be set before setting this bit to 1. 1 ALERT Enable R/W This bit is used to enable or disable the ALERT output. Setting the bit to 1 enables the ALERT output; setting the bit to 0 disables the ALERT output. 2 Reserved — — 3 ALERT Clear R/W This bit is used to clear the ALERT output when it is set to high. It does not affect the Interrupt Status Register. The monitoring loop does not start until the bit is set to zero. 4 Line Frequency Select R/W This bit controls the internal clock frequency. Setting the bit to 1 changes the clock frequency to 51.2kHz from 61.4kHz. This can improve the measurement accuracy when the power-line frequency is at 50Hz. 5 Short Cycle R/W This bit reduces the conversion time by a factor of 4 when it is set to 1. 6 Reserved — 7 Reset R/W — This bit is used as a reset signal for the register initialization. The 1 of this bit resets all the register values into the power-up default mode, including bit 7 itself. Table 5. Interrupt Status Register (Address 41h, Power-Up Default = 00h) BIT NAME READ/WRITE DESCRIPTION 0 2.5VIN-Error R A 1 indicates either a high or low limit has been exceeded at the 2.5VIN input. 1 1.8VIN-Error R A 1 indicates either a high or low limit has been exceeded at the 1.8VIN input. 2 5VIN-Error R A 1 indicates either a high or low limit has been exceeded at the 5VIN input. 3 VCC-Error R A 1 indicates either a high or low limit has been exceeded at the VCC input. 4 Temp-Error R A 1 indicates either a high or low limit has been exceeded at the internal temperature sensor. The conditions that generate and clear this bit depend on the temperature interrupt mode selected by bits 0 and 1 in the Temperature Configuration Register. 5, 6, 7 Reserved — — The POR state of the THOT register is 0101 0000 or +80°C. The POR state of the THYST register is 0100 0001 or +65°C. High and low limits for the voltage inputs are stored in registers 2Bh through 32h. If a measured voltage is less than VLOW or greater than VHIGH, an ALERT is asserted. The POR states of the high and low voltage limits are 1.1 and 0.9 times the nominal voltage for each input. 8 Interrupt Status Byte Functions The Interrupt Status Register records temperature or voltage fault conditions whenever a limit is exceeded (Table 5). Bits 0 through 3 correspond to the 2.5V, 1.8V, 5V, and VCC voltage inputs and bit 4 corresponds to the temperature. If a threshold has been crossed, the appropriate bit contains a 1. In the default and one-time interrupt modes, reading the status register clears the register until a new out-of-range condition is detected. _______________________________________________________________________________________ Temperature Sensor and System Monitor in a 10-Pin µMAX MAX6683 Table 6. Interrupt Mask Register (Address 43h, Power-Up Default = 00h) BIT NAME READ/WRITE DESCRIPTION 0 2.5V R/W Setting the bit to 1 disables the Interrupt Status Register bit (bit 0) and the ALERT output for the 2.5VIN input. 1 1.8V R/W Setting the bit to 1 disables the Interrupt Status Register bit (bit 1) and the ALERT output for the 1.8VIN input. 2 5V R/W Setting the bit to 1 disables the Interrupt Status Register bit (bit 2) and the ALERT output for the 5VIN input. 3 3.3V R/W Setting the bit to 1 disables the Interrupt Status Register bit (bit 3) and the ALERT output for the VCC input. 4 Temp. R/W Setting the bit to 1 disables the Interrupt Status Register bit (bit 4) and the ALERT output for temperature. 5, 6, 7 Reserved — — Table 7. Temperature Configuration Register (Address 4Bh, Power-Up Default = 00h) BIT 0, 1 2−7 NAME Hot Temperature Interrupt Select Reserved READ/WRITE R/W DESCRIPTION Bit 1, bit 0 = 00: Default mode Bit 1, bit 0 = 01: One-time interrupt mode Bit 1, bit 0 = 10: Comparator mode Bit 1, bit 0 = 11: Default mode — ALERT Interrupts An out-of-range voltage or temperature causes the ALERT output signal to be asserted. However, if the assertion is caused by an out-of-range temperature, the ALERT output can operate in one of three different modes: default, one-time interrupt, or comparator mode. In the default and one-time interrupt modes, the ALERT signal and Interrupt Status Register are cleared by reading the Interrupt Status Register (Table 5). In comparator mode, ALERT is only cleared when the fault condition is removed. Reading the Interrupt Status Register clears all but bit 4 of the Status Register if the fault condition is not removed. Reading the Interrupt Status Register with the fault condition removed clears the entire register. Unless the fault is removed, ALERT is reasserted after the next conversion cycle. The ALERT output can also be masked by writing to the appropriate bits in the Interrupt Mask Register (Table 6) or by setting bit 1 of the Configuration Register (Table 4) to zero. The interrupt does not halt conversions. New temperature and voltage data continue to be available over the SMBus interface after ALERT is asserted. The three temperature ALERT modes are shown in Figure 1 and — are selected through the Temperature Configuration Register (Table 7). The ALERT output pin is open drain, so the device can share a common interrupt line. Default Mode An interrupt is initiated when temperature exceeds THOT (address 39h). The interrupt is cleared only by reading the Interrupt Status Register. An interrupt continues to be generated on subsequent measurements until the temperature goes below THYST (address 3Ah). One-Time Interrupt Mode An interrupt is initiated when temperature exceeds THOT (address 39h). The interrupt is cleared only by reading the Interrupt Status Register. The next interrupt is then initiated when temperature falls below the THYST (address 3Ah). Comparator Mode An interrupt is initiated when temperature exceeds THOT (address 39h). The ALERT output remains asserted low until the temperature goes below THOT. Reading the Interrupt Status Register does not clear the ALERT output or interrupt status bit in the register. The interrupt continues to be generated on subsequent measurements until the temperature falls below THOT. _______________________________________________________________________________________ 9 MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX TEMPERATURE MONITORING CYCLE INTERRUPT STATUS READ THOT THYST ALERT DEFAULT MODE ALERT ONE-TIME INTERRUPT MODE ALERT COMPARATOR MODE Figure 1. Alert Response to Temperature Interrupts Write Byte Format S ADDRESS W/R 7 bits 0 ACK COMMAND ACK DATA 8 bits Slave Address: equivalent to chip-select line of a 3-wire interface ACK P 8 bits Command Byte: selects which register you are writing to Data Byte: data goes into the register set by the co mma nd byte ( to se t thresholds, configuration masks, and sampling rate) Read Byte Format S ADDRESS W/R 7 bits 0 ACK COMMAND ACK S 8 bits Slave Address: equivalent to chip-select line of a 3-wire interface Command Byte: selects which register you are reading from Send Byte Format S ADDRESS W/R 7 bits 1 ACK Slave Address: repeated due to change in dataflow direction W/R 7 bits 0 ACK COMMAND ACK P S ADDRESS 8 bits 7 bits W/R Data Byte: reads from the register set by the command byte ADDRESS W/R 7 bits 0 ACK COMMAND ACK 8 bits S ACK DATA A P 8 bits 1 Data Byte: reads data from the register commanded by the last Read Byte or Write Byte transmission; also used for SMBus alert Response return address Read Word Format ADDRESS 7 bits W/R ACK 1 DATA_LOW_byte 8 bits ACK DATA_HIGH_byte 8 bits Shaded = Slave transmission A = Not acknowledged Figure 2. SMBus Protocols 10 P Receive Byte Format ADDRESS S = Start condition P = Stop condition A 8 bits Data Byte: writes data to the register commanded by the last Read Byte or Write Byte transmission S DATA ______________________________________________________________________________________ A P Temperature Sensor and System Monitor in a 10-Pin µMAX tLOW B tHIGH C D E F G H I J K L MAX6683 A M SMBCLK SMBDATA tHD:STA tSU:STA 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 tHD:DAT tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO MASTER K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION 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 Figure 3. SMBus Write Timing Diagram 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 tSU:DAT tSU:STO tBUF 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 CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION Figure 4. SMBus Read Timing Diagram SMBus/I2C-Compatible Digital Interface From a software prospective, the MAX6683 appears as a set of byte-wide registers that contain voltage and temperature data, alarm threshold values, or control bits. The device employs five standard SMBus protocols: write byte, read byte, read word, send byte, and receive byte (Figures 2, 3, 4). Slave Address The device address can be set to one of four different values by pin strapping ADD to GND, SDA, SCL, or VCC, so more than one MAX6683 can reside on the same bus without address conflicts (Table 1). The address pin state is checked at the beginning of each SMBus/I2C transaction and is insensitive to glitches on V CC . Any address code can also be written to the Serial Address Register and overwrites the code set by connecting the ADD pin until the MAX6683 is taken through a POR cycle. The MAX6683 also responds to the SMBus alert response address (see Alert Response Address). ______________________________________________________________________________________ 11 MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX UPPER BYTE D10 D9 D8 D7 D6 LOWER BYTE D5 D4 D3 D2 D1 D0 X X X X X X X X 11-BIT READ FORMAT UPPER BYTE D8 D7 D6 D5 D4 LOWER BYTE D3 D2 D1 D0 X X X 9-BIT READ FORMAT X X = DON'T CARE Figure 5. Read Temperature Format Alert Response Address The SMBus alert response interrupt pointer provides quick fault identification for simple slave devices that lack the complex, expensive logic needed to be a bus master. Usually the ALERT outputs of several slave devices are wire-ORed to the same interrupt input of the host master. Upon receiving an interrupt signal, the host master can broadcast a receive byte transmission (Figure 2) with the alert response address (0001 100). A read operation is denoted by a 1 in the eighth address bit. Then, any slave device that generated an interrupt attempts to identify itself by putting its own address on the bus. The alert response can activate several different slave devices simultaneously, similar to the I2C general call. If more than one slave attempts to respond, bus arbitration rules apply, and the device with the lower address code wins. The losing device does not generate an acknowledge signal and continues to hold the interrupt line low until serviced. The MAX6683 does not automatically clear its ALERT when it responds to an alert response address. The host master must then clear or mask the ALERT by reading the Interrupt Status Register, writing to the Interrupt Mask Register, or setting bit 1 of the Configuration Register to zero before it can identify other slaves generating an interrupt. Command Byte Functions The 8-bit Command Byte Register (Table 1) is the master index that points to the other data, configuration, limits, and address registers within the MAX6683. The functions of those other registers are described below. Configuration Byte Functions The Configuration Register (Table 4) is a read-write register with several functions: 12 • Bit 0 puts the MAX6683 into software standby mode (STOP) or autoconvert (START) mode. The 2-wire interface is still active in the standby mode. All voltage and temperature limits should be set before setting this bit to 1. • Bit 1 enables and disables the ALERT output. Setting this bit to 1 enables the ALERT output. • Bit 2 is reserved. • Bit 3 clears the ALERT output and stops the monitoring loop when set to 1. Clearing the output does not affect the contents of the Interrupt Status Registers. • Bit 4 sets the analog-to-digital conversion speed to minimize interference from power-line frequencies. Setting this bit to 1 can improve accuracy when the power-line frequency is 50Hz. When the power-line frequency is 60Hz, bit 4 should be zero. • Bit 5 reduces the oversampling ratio in the ADC from 8 to 2. This reduces the monitoring cycle time by a factor of 4 to typically 50ms at the cost of reduced noise rejection. • Bit 6 is reserved. • Bit 7 resets all register values to their power-up default values. To reset all registers, set bit 7 to 1. This also resets bit 7 to its power-up value of zero. Read Temperature The MAX6683 reads out temperature in an 8-, 9-, or 11-bit two's complement format. To obtain the 8-bit temperature data (7 bits plus sign), execute a Read Byte command to the Temperature Data Register (address 27h). To obtain the 11-bit temperature data (10 bits plus sign), execute a Read Word command to the Temperature Data Register (address 27h). When per- ______________________________________________________________________________________ Temperature Sensor and System Monitor in a 10-Pin µMAX Sensing Circuit Board and Component Temperatures VCC 1.8VIN 2.5VIN 5.0VIN Applications Information INPUT VOLTAGE SCALING AND MULTIPLEXER ADC DATA AND CONTROL LOGIC TEMPERATURE SENSOR VOLTAGE REFERENCE I2C/SMBusCOMPATIBLE INTERFACE SDA SCL ALERT ADD forming a Read Word operation, the MAX6683 writes the 11 bits of data to the bus in two 8-bit words. The upper byte contains the MSBs, while the lower byte contains the 3LSBs (Figure 5). D9–D3 of the upper byte represent the whole decimal number of the temperature conversion and D10 is sign. D2–D0 of the lower byte represent 1/2, 1/4, 1/8 of a degree, respectively, and the remaining bits are disregarded. Nine-bit temperature data (8 bits plus sign) is obtained by setting bit 5 of the Configuration Register (address 40h) to 1, reducing the conversion time by a factor of four, and executing a Read Word command to the Temperature Data Register (address 27h). The upper byte contains the MSBs, while the lower byte contains the LSB (Figure 5). D7–D1 of the upper byte represent the whole decimal number of the temperature conversion and D0 is sign. D0 of the lower byte represents 1/2 of a degree, and the remaining bits are disregarded. Temperature sensor ICs like the MAX6683 that sense their own die temperatures must be mounted on or close to the object whose temperature they are intended to measure. Because there is a good thermal path between the 10-pin µMAX package’s metal leads and the IC die, the MAX6683 can accurately measure the temperature of the circuit board to which it is soldered. 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 thermal path between the plastic package and the die is not as good as the path through the leads, so the MAX6683, like all temperature sensors in plastic packages, is less sensitive to the temperature of the surrounding air than to the temperature of the leads. Wiring and circuits must be kept insulated and dry to avoid leakage and corrosion, especially if they operate at cold temperatures where condensation can occur. Chip Information TRANSISTOR COUNT: 13,446 PROCESS: BiCMOS ______________________________________________________________________________________ 13 MAX6683 Functional Diagram Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) e 10LUMAX.EPS MAX6683 Temperature Sensor and System Monitor in a 10-Pin µMAX 4X S 10 10 INCHES H Ø0.50±0.1 0.6±0.1 1 1 0.6±0.1 BOTTOM VIEW TOP VIEW D2 MILLIMETERS MAX DIM MIN 0.043 A 0.006 A1 0.002 A2 0.030 0.037 0.120 D1 0.116 0.118 0.114 D2 0.116 0.120 E1 0.118 E2 0.114 0.199 H 0.187 L 0.0157 0.0275 L1 0.037 REF b 0.007 0.0106 e 0.0197 BSC c 0.0035 0.0078 0.0196 REF S α 0° 6° MAX MIN 1.10 0.15 0.05 0.75 0.95 3.05 2.95 3.00 2.89 3.05 2.95 2.89 3.00 4.75 5.05 0.40 0.70 0.940 REF 0.177 0.270 0.500 BSC 0.090 0.200 0.498 REF 0° 6° E2 GAGE PLANE A2 c A b A1 α E1 L D1 L1 FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 10L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0061 REV. 1 1 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. 14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.