Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
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Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
MAX6655/MAX6656 precise voltage temperature monitors. digital thermometer reports temperature remote sensors temperature. remote sensors diode-connected transistors-typically low-cost, easily mounted 2N3906 type-that replace conventional thermistors thermocouples. Remote accuracy ±1°C multiple transistor manufacturers with calibration necessary. remote channels also measure temperature other ICs, such microprocessors, that contain substrate-connected with collector grounded base emitter available temperature-sensing purposes. temperature digitized with 11-bit resolution. MAX6655/MAX6656 also measure their supply voltage three external voltages with 8-bit resolution. Each voltage input's sensitivity give approximately 3/4-scale output code when input voltage nominal value. MAX6655 operates supply second voltage monitor 3.3V. MAX6656 operates +3.3V supply second voltage monitor 2-wire serial interface accepts standard SMBusWrite Byte, Read Byte, Send Byte, Receive Byte commands program alarm thresholds read data. MAX6655/MAX6656 also provide SMBus alert response timeout functions. MAX6655/MAX6656 measure automatically autonomously, with conversion rate programmable. adjustable rate allows user control supply current. addition SMBus ALERT output, MAX6655/ MAX6656 feature OVERT output, which used temperature reset that remains active only while temperature above maximum temperature limit. OVERT output optimal control system shutdown. Three Temperature Channels Remote Junctions Local Sensor Four Voltage Channels +12V, +5V, +3.3V, +2.5V Three External Monitors Internal Supply Monitor 11-Bit, 0.125°C Resolution High Accuracy: ±1°C Over +60°C +100°C Temperature Range Programmable Under/Over-Threshold Alarms Programmable Power-Saving Mode Calibration Required SMBus/I2C*-Compatible Interface OVERT Output Control System Shutdown
Features
MAX6655/MAX6656
Ordering Information
PART MAX6655MEE MAX6656MEE TEMP RANGE -55°C +125°C -55°C +125°C PINPACKAGE QSOP QSOP CODE E16-5 E16-5
Typical Application Circuit appears data sheet.
Configuration
VIEW
STBY SMBCLK OVERT DXP1 DXN1 ADD0 ADD1 DXP2 DXN2
Applications
Notebooks Thin Clients Servers Workstations Communication Equipment Desktop
SMBus trademark Intel Corp. *Purchase components from Maxim Integrated Products, Inc., sublicensed Associate Companies, conveys license under Philips Patent Rights these components system, provided that system conforms Standard Specification defined Philips.
MAX6655 MAX6656
SMBDATA ALERT VIN2 VIN1 VIN3
QSOP
Maxim Integrated Products
pricing, delivery, ordering information, please contact Maxim/Dallas Direct! 1-888-629-4642, visit Maxim's website www.maxim-ic.com.
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
ABSOLUTE MAXIMUM RATINGS
.-0.3V DXN_ .-0.3V +0.8V SMBCLK, SMBDATA, ALERT, STBY, OVERT .-0.3V VIN1 GND.-0.3V +16V VIN2 GND.-0.3V VIN3 GND.-0.3V Other Pins GND.-0.3V (VCC 0.3V) SMBDATA, ALERT, OVERT Current.-1mA +50mA DXN_ Current.±1mA Protection (all pins, Human Body Model) .2000V Continuous Power Dissipation +70°C) 16-Pin QSOP (derate 8.30mW/°C above +70°C).667mW Operating Temperature Range .-55°C +125°C Junction Temperature .+150°C Storage Temperature Range .-65°C +150°C Lead Temperature (soldering, 10s) .+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC +3.0V +3.6V MAX6656, +4.5V +5.5V MAX6655, -55°C +125°C, unless otherwise noted. Typical values +3.3V MAX6656, +5.0V MAX6655, +25°C.)
PARAMETER Supply Range Accuracy (Local Sensor) Accuracy (Remote Sensor) Temperature Measurement Resolution Input Impedance Total Error Resolution Undervoltage Lockout Threshold Undervoltage Lockout Hysteresis Power-On Reset (POR) Threshold Threshold Hysteresis Standby Current Leakage Current Average Operating Current Conversion Time Single Temperature Measurement Monitoring Cycle Time tCON tMONI SMBus static, STBY standby mode Continuous temperature mode From stop conversion completed Total temperature plus voltage measurements VCC, falling edge UVLO input, disables conversion, falling edge 2.50 VIN1, VIN2, VIN3 input resistance VIN1, VIN2, VIN3 between 120% nominal 2.70 1000 2.90 ±1.5 SYMBOL +60°C +100°C +125°C +60°C +100°C +120°C 0.125 CONDITIONS ±1.5 UNITS Bits Bits
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
ELECTRICAL CHARACTERISTICS (continued)
(VCC +3.0V +3.6V MAX6656, +4.5V +5.5V MAX6655, -55°C +125°C, unless otherwise noted. Typical values +3.3V MAX6656, +5.0V MAX6655, +25°C.)
PARAMETER Remote Junction Current (DXP, DXN) Logic Input Voltage Logic Input High Voltage Input Leakage Current Output Sink Current Input Capacitance SMBus Timeout ALERT, OVERT Output Sink Current Output High Leakage Current SMBus TIMING Serial Clock Frequency Free Time Between STOP START Condition START Condition Setup Time Repeat START Condition Setup Time START Condition Hold Time STOP Condition Setup Time Clock Period Clock High Period Data Setup Time Data Hold Time Receive SMBCLK/SMBDATA Rise Time Receive SMBCLK/SMBDATA Fall Time Pulse Width Spike Suppressed tSU:STA tHD:STA tSU:STO tLOW tHIGH tSU:DAT tHD:DAT SMBDATA SMBCLK SMBCLK SMBDATA SMBDATA SMBCLK (Note fSCL tBUF +0.6V +5.5V ILEAK SMBCLK SMBDATA time reset SYMBOL High level level +3.0V +5.5V +3.0V +5.5V +0.6V CONDITIONS UNITS
MAX6655/MAX6656
SMBus INTERFACE (SMBCLK, SMBDATA, STBY)
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Typical Operating Characteristics
+25°C, unless otherwise noted.)
TEMPERATURE ERROR POWER-SUPPLY NOISE FREQUENCY
MAX6655/MAX6656 toc02
REMOTE TEMPERATURE ERROR BOARD RESISTANCE
MAX6655/MAX6656 toc01
REMOTE TEMPERATURE ERROR REMOTE-DIODE TEMPERATURE
REMOTE TEMPERATURE ERROR (°C) RANDOM SAMPLE 2N3906
REMOTE TEMPERATURE ERROR (°C)
TEMPERATURE ERROR (°C)
PATH PATH (5V)
SQUARE WAVE APPLIED WITH BYPASS CAPACITOR 250mVp-p REMOTE DIODE
LEAKAGE RESISTANCE
TEMPERATURE (°C)
FREQUENCY (MHz)
REMOTE TEMPERATURE ERROR COMMON-MODE NOISE FREQUENCY
REMOTE TEMPERATURE ERROR (°C) 200mVp-p 100mVp-p FREQUENCY (MHz)
MAX6655/MAX6656 toc04
REMOTE TEMPERATURE ERROR DXP-DXN CAPACITANCE
MAX6655/MAX6656 toc05
STANDBY SUPPLY CURRENT CLOCK FREQUENCY
SUPPLY CURRENT (µA) SMBCLK DRIVEN RAIL-TO-RAIL
MAX6655/MAX6656 toc06
REMOTE TEMPERATURE ERROR (°C)
SQUARE WAVE AC-COUPLED
DXP-DXN CAPACITANCE (nF)
1000 SMBCLK FREQUENCY (kHz)
STANDBY SUPPLY CURRENT SUPPLY VOLTAGE
MAX6655/MAX6656 toc07
RESPONSE THERMAL SHOCK
TEMPERATURE (°C)
MAX6655/MAX6656 toc08
VOLTAGE ACCURACY TEMPERATURE
VIN2 VIN3 INPUT VOLTAGES NOMINAL VIN1
MAX6655/MAX6656 toc09
SUPPLY CURRENT (µA) ADD0, ADD1 HIGH-Z SUPPLY VOLTAGE ADD0, ADD1
REMOTE DIODE IMMERSED +115°C FLUORINERT BATH
OUTPUT VOLTAGE
TIME
TEMPERATURE (°C)
MAX6655/MAX6656 toc03
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
Description
NAME DXP1 DXN1 ADD0 ADD1 DXP2 DXN2 VIN3 VIN1 VIN2 ALERT SMBDATA OVERT SMBCLK STBY FUNCTION Supply Voltage. MAX6655; +3.3V MAX6656. Bypass with 0.1µF capacitor. External Diode Positive Connection. DXP1 combined current source positive input remote-diode remote-sensing junction used, connect DXP1 DXN1. External Diode Negative Connection. DXN1 combined current sink negative input remote-diode DXN1 normally biased diode voltage above ground. SMBus Slave Address Select Input. ADD0 ADD1 sampled upon power-up. Table truth table. SMBus Slave Address Select Input. ADD0 ADD1 sampled upon power-up. External Diode Positive Connection. DXP2 combined current source positive input remote-diode remote-sensing junction used, connect DXP2 DXN2. External Diode Negative Connection. DXN2 combined current sink negative input remote-diode DXN2 normally biased diode voltage above ground. Ground External Voltage Monitor VIN3 typically used monitor +2.5V supplies. External Voltage Monitor VIN1 typically used monitor +12V supplies. External Voltage Monitor VIN2 typically used monitor voltage supplies +3.3V MAX6655 +5.0V MAX6656. SMBus Alert (Interrupt) Output, Open-Drain SMBus Serial-Data Input/Output, Open-Drain Overtemperature Alarm Output, Open-Drain. OVERT unlatched alarm output that responds programmed maximum temperature limit temperature channels. SMBus Serial-Clock Input Hardware Standby Input. Drive STBY low-power standby mode. Drive STBY high normal operating mode. Temperature comparison threshold data retained standby mode.
MAX6655/MAX6656
Detailed Description
MAX6655/MAX6656 voltage temperature monitors that communicate through SMBus-compatible interface with microprocessor microcontroller thermal management applications. Essentially 11-bit serial with sophisticated front end, MAX6655/MAX6656 contain switched-current source, multiplexer, ADC, SMBus interface, associated control logic. Temperature data from loaded into data register, where automatically compared with data previously stored over/undertemperature alarm threshold registers. Temperature data read time with bits resolution. MAX6655/MAX6656 monitor external supply voltages typically 12V, 2.5V, 3.3V MAX6655 5.0V MAX6656, well their supply voltage. voltage inputs converted 8-bit code using ADC. Each input voltage scaled down
on-chip resistive-divider that output, nominal input voltage, approximately ADC's full-scale range, decimal count 198.
averaging integrates over 40ms period (typ) with excellent noise rejection. converts temperature measurement 125ms (typ) voltage measurement 62.5ms (typ). temperature measurements, multiplexer automatically steers bias currents through remote diode, then forward voltage measured temperature computed. input biased diode drop above ground internal diode inputs differential measurement. worst-case DXP-DXN differential input voltage range +0.25V +0.95V. Excess resistance series with remote diode causes about +1/2°C error/. 200µV offset voltage DXP-DXN causes about -1°C error.
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Write Byte Format ADDRESS bits Slave Address: equivalent chip-select line 3-wire interface Read Byte Format ADDRESS bits Slave Address: equivalent chip-select line COMMAND bits Command Byte: selects which register reading from ADDRESS bits Slave Address: repeated change dataflow direction Receive Byte Format COMMAND bits Data Byte: writes data register commanded last read byte write byte transmission Start condition Stop condition Shaded Slave transmission acknowledged ADDRESS bits DATA bits Data Byte: reads data from register commanded last read byte write byte transmission; also used SMBus alert response return address DATA bits Data Byte: reads from register command byte COMMAND bits Command Byte: selects which register writing DATA bits Data Byte: data goes into register byte thresholds, configuration masks, sampling rate)
Send Byte Format ADDRESS bits
Figure SMBus/I2C Protocols
Conversion Sequence
Each time conversion begins, channels converted, results measurements available after conversion. BUSY status Status Byte shows that device actually performing conversion; however, even busy, results previous conversion always available. conversion sequence MAX6655 (MAX6656) External Diode External Diode Internal Diode, VIN3, VIN2 (VCC), VIN1, (VIN2). always converts maximum speed, time between sequence conversions adjustable. Conversion Rate Control Byte (Table shows possible delays between conversions. Disabling voltage temperature measurements with Configuration Byte makes complete conversion sequence faster.
Configuration Byte register. Hardware software standby modes behave identically; data retained memory, SMBus interface alive listening reads writes. Standby mode shutdown mode. Activity SMBus draws extra supply current (see Typical Operating Characteristics). Enter hardware standby mode forcing STBY low. notebook computer, this line connected system SUSTAT# suspend-state signal. STBY state overrides software conversion command. hardware software standby command received while conversion progress, conversion cycle truncated, data from that conversion latched into Temperature Reading register. previous data changed remains available. Supply current during 125ms conversion typically 550µA. Between conversions, instantaneous supply current about 25µA, current consumed conversion-rate timer. With very supply voltages (under threshold), supply current higher address input bias currents.
Low-Power Standby Mode
Standby mode disables reduces supply current drain (typ). Enter standby mode forcing STBY through RUN/STOP
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
tLOW tHIGH
SMBCLK
SMBDATA
tSU:STA
tHD:STA
tSU:DAT
tHD:DAT
tSU:STO tBUF
START CONDITION ADDRESS CLOCKED INTO SLAVE ADDRESS CLOCKED INTO SLAVE CLOCKED INTO SLAVE SLAVE PULLS SMBDATA LINE
ACKNOWLEDGE CLOCKED INTO MASTER DATA CLOCKED INTO SLAVE DATA CLOCKED INTO SLAVE MASTER PULLS DATA LINE
ACKNOWLEDGE CLOCKED INTO SLAVE ACKNOWLEDGE CLOCK PULSE STOP CONDITION START CONDITION
Figure SMBus/I2C Write Timing Diagram
tLOW
tHIGH
SMBCLK
SMBDATA
tSU:STA
tHD:STA
tSU:DAT
tHD:DAT
tSU:STO tBUF
START CONDITION ADDRESS CLOCKED INTO SLAVE ADDRESS CLOCKED INTO SLAVE CLOCKED INTO SLAVE SLAVE PULLS SMBDATA LINE
ACKNOWLEDGE CLOCKED INTO MASTER DATA CLOCKED INTO MASTER DATA CLOCKED INTO MASTER MASTER PULLS DATA LINE
ACKNOWLEDGE CLOCKED INTO SLAVE ACKNOWLEDGE CLOCK PULSE STOP CONDITION START CONDITION
Figure SMBus/I2C Read Timing Diagram
SMBus Digital Interface
From software perspective, MAX6655/MAX6656 appear byte-wide registers that contain temperature data, voltage data, alarm threshold values, control bits. standard SMBus 2-wire serial interface read temperature data write control bits alarm threshold data.
MAX6655/MAX6656 employ four standard SMBus protocols: Write Byte, Read Byte, Send Byte, Receive Byte (Figures shorter protocols (Receive Send) allow quicker transfers, provided that correct data register previously selected Write Read Byte instruction. caution with shorter protocols multimaster systems, since second master could overwrite Command Byte without informing first master.
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
+5.5V
HIGH alarms their settings. Similarly, DXP_ short circuited reads -1°C both remote channels, ALERT outputs activated.
MAX6655 MAX6656 SMBCLK SMBDATA ALERT OVERT DXP2 ADD0 ADD1 DXN2 SYSTEM SHUTDOWN
Alert Interrupts
Normally, ALERT interrupt output signal latched cleared either responding Alert Response Address reading Status register. Interrupts generated response HIGH TLOW, VHIGH VLOW comparisons, when remote diode faulted. interrupt does halt automatic conversions; temperature data continues available over SMBus interface after ALERT asserted. interrupt output open-drain multiple devices share common interrupt line. interface responds SMBus Alert Response address, interrupt pointer return-address feature (see Alert Response Address section). Before taking corrective action, always check ensure that interrupt valid reading current temperature. alert activates only once crossing given temperature threshold prevent reentrant interrupts. enable interrupt, rewrite value violated temperature threshold.
SMBus SERIAL INTERFACE HOST)
2N3906
2200pF
Figure System Shutdown Application
temperature data stored internal registers RRTE, RRT2, RLTS bits sign two's complement form with each representing 1°C. Additionally, 3MSBs Extended Temperature register contain fractional temperature data with +0.125°C resolution (Tables voltage data stored RV0, RV1, RV2, bits binary form (Table
Alert Response Address
SMBus Alert Response interrupt pointer provides quick fault identification simple slave devices that lack complex, expensive logic needed master. Upon receiving ALERT interrupt signal, host master broadcast Receive Byte transmission Alert Response slave address (0001100). slave device that generated interrupt then attempts identify itself putting address (Table Alert Response activate several different slave devices simultaneously, similar General Call. more than slave attempts respond, arbitration rules apply, device with lower address code wins. losing device does generate acknowledgment continues hold ALERT line until serviced (implies that host interrupt input level sensitive). alert cleared after slave address returned host.
OVERT Output
OVERT output unlatched open-drain output that behaves thermostat control system shutdown (Figure This output responds current temperature. current temperature above THIGH, OVERT activates does inactive until temperature drops below THIGH.
Diode Fault Alarm
continuity fault detector detects whether remote diode open-circuit condition, short-circuit GND, short-circuit DXP-to-DXN condition. beginning each conversion, diode fault checked, Status Byte updated. This fault detector simple voltage detector; rises above (typ) below VDXN 50mV (typ), fault detected. Note that diode fault isn't checked until conversion initiated, immediately after POR, status byte indicates fault present, even diode path broken. remote channel shorted (DXP GND), reads 1111 1111 trip either
Command Byte Functions
8-bit Command Byte register (Table master index that points other registers within MAX6655/MAX6656. register's state 0000 0000, Receive Byte transmission protocol that lacks Command Byte) that occurs immediately after returns current internal temperature data.
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
Alarm Threshold Registers
Seventeen registers store ALARM OVERT threshold data. MAX6655/MAX6656 contain three registers high-temperature HIGH three lowtemperature (TLOW), four high-voltage (VHIGH), four low-voltage (VLOW) thresholds, three more registers store OVERT data. measured temperature voltage exceeds corresponding alarm threshold value, ALARM interrupt asserted. OVERT asserts when temperature exceeds corresponding alarm threshold value. state THIGH register full scale (0111 1111 +127°C). state TLOW register 1100 1001 -55°C. temperature. base resistance less than 100. Tight specification forward-current gain (+50 +150, example) indicates that manufacturer good process controls that devices have consistent characteristics. power transistors.
MAX6655/MAX6656
Self-Heating
Thermal mass significantly affect time required temperature sensor respond sudden change temperature. thermal time constant 16-pin QSOP package about 140s still air. When measuring local temperature, senses temperature board which soldered. leads provide good thermal path between board traces MAX6655/MAX6656 die. Thermal conductivity between MAX6655/MAX6656 ambient poor comparison. Because thermal mass board greater than that MAX6655/MAX6656, device follows temperature changes board with little perceivable delay. When measuring temperature with discrete remote sensors, smaller packages, such SOT23, yields best thermal response time. Take care account thermal gradients between heat source sensor, ensure that stray currents across sensor package interfere with measurement accuracy. When measuring temperature other with on-chip sense junction, thermal mass virtually effect; measured temperature junction tracks actual temperature within conversion cycle. Self-heating does significantly affect measurement accuracy. Remote-sensor self-heating diode current source negligible. local diode, worst-case error occurs when autoconverting fastest rate simultaneously sinking maximum current ALERT output. example, minimum delay between conversions, with ALERT sinking 1mA, typical power dissipation 550µA 0.4V 1mA. Package about 150°C/W, with copper board heat sinking, resulting temperature rise 3.1mW 150°C/W +0.46°C Even with these contrived circumstances, difficult introduce significant self-heating errors.
Configuration Byte Functions
Configuration Bytes (Tables used mask (disable) interrupts, disable temperature voltage measurements, device software standby mode. serial interface read back contents these registers.
Status Byte Functions
Status Byte registers (Tables indicate which any) temperature voltage thresholds have been exceeded. Status Byte also indicates whether converting whether there fault remote-diode DXP-DXN path. After POR, normal state flag bits zero, except MSB, assuming none alarm conditions present. toggles between indicating whether converting not. Status Byte cleared successful read that Status Byte. Note that ALERT interrupt latch clears when status flag read, immediately asserts after next conversion fault condition persists. High alarm conditions exist same time Status Byte because MAX6655/MAX6656 correctly reporting environmental changes.
Applications Information
Remote-Diode Selection
Remote temperature accuracy depends having good-quality, diode-connected transistor. Table appropriate discrete transistors. MAX6655/ MAX6656 directly measure temperature CPUs other with on-board temperature-sensing transistors. transistor must small-signal type with relatively high forward voltage. This ensures that input voltage within input voltage range. forward voltage must greater than 0.25V 10µA highest expected temperature. forward voltage must less than 0.95V 100µA lowest expect-
Noise Filtering
integrating inherently good noise rejection, especially low-frequency signals such 60Hz/120Hz power-supply hum. Micropower operation
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
places constraints high-frequency noise rejection. board carefully with proper external noise filtering high-accuracy remote measurements electrically noisy environments. Filter high-frequency electromagnetic interference (EMI) with external 2200pF capacitor connected between inputs. This capacitor increased about 3300pF (max), including cable capacitance. capacitance higher than 3300pF introduces errors rise time switched-current source. necessary, bypass VIN_ pins with appropriatevalue capacitor greater noise performance. resistance series with inputs. Series resistance degrades voltage measurements.
10MILS 10MILS MINIMUM 10MILS 10MILS
Board Layout
Place MAX6655/MAX6656 close practical remote diode. noisy environment, such computer motherboard, this distance (typ) more, long worst noise sources (such CRTs, clock generators, memory buses, ISA/PCI buses) avoided. route DXP-DXN lines next deflection coils CRT. Also, route traces across fast memory bus, which easily introduce +30°C error, even with good filtering. Otherwise, most noise sources fairly benign. Route traces parallel close each other, away from high-voltage traces such +12VDC. Avoid leakage currents from board contamination. leakage path from ground causes approximately +1°C error. Connect guard traces either side DXP-DXN traces when possible (Figure With guard traces place, routing near high-voltage traces longer issue. Route vias crossunders possible minimize copper/solder thermocouple effects. When introducing thermocouple, make sure that both paths have matching thermocouples. general, board-induced thermocouples serious problem. copper-solder thermocouple exhibits 3µV/°C, takes approximately 200µV voltage error DXP-DXN cause measurement error, most parasitic thermocouple errors swamped out. wide traces. Narrow traces more inductive tend pick radiated noise. 10-mil widths spacings recommended Figure absolutely necessary they offer only minor
Figure Recommended DXP/DXN Traces
improvement leakage noise), them where practical. Note that copper cannot used shield. Placing copper ground plane between DXPDXN traces traces carrying high-frequency noise signals does help reduce EMI.
Twisted Pair Shielded Cables
remote-sensor distances longer than 8in, particularly noisy environments, twisted pair recommended. practical length 12ft (typ) before noise becomes problem, tested noisy electronics laboratory. longer distances, best solution shielded twisted pair like that used audio microphones. example, Belden #8451 works well distances 100ft noisy environment. Connect twisted pair shield GND, leave shield's remote unterminated. Excess capacitance limits practical remote-sensor distances (see Typical Operating Characteristics). very long cable runs, cable's parasitic capacitance often provides noise filtering, recommended 2200pF capacitor often removed reduced value. Cable resistance also affects remote-sensor accuracy. series resistance introduces about +1/2°C error.
Chip Information
TRANSISTOR COUNT: 26,783 PROCESS: BiCMOS
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Table Conversion Rate Control Byte
DATA (RCRA, 04H) WAIT TIME BETWEEN CONVERSION SEQUENCES 0.125 0.250 0.500 1.000 2.000 4.000 4.000
Table Extended Resolution Register
FRACTIONAL TEMPERATURE (°C) 0.125 0.250 0.375 0.500 0.625 0.750 0.875 DIGITAL OUTPUT 0000 0000 0010 0000 0100 0000 0110 0000 1000 0000 1010 0000 1100 0000 1110 0000
Table Temperature Data Format
TEMP (°C) 130.00 127.00 126.00 25.25 0.50 -0.625 Diode Fault (Short Open) ROUNDED TEMP (°C) +127 +127 +126 DIGITAL OUTPUT 1111 1111 1111 1001 0001 0000 1111 1111 1111 1111
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Table Voltage Data Format
OUTPUT CODE weight scale) scale) scale) scale) INPUT VOLTAGE VIN1 (+12V) 57.1mV 4.343V 4.400V 4.400V 4.457V 4.457V 4.514V 8.000V 8.057V 12.000V 12.057V 12.686V 12.743V 12.743V 12.800V 14.228V 14.285V INPUT VOLTAGE VIN2 (+5V) 23.8mV 1.810V 1.833V 1.833V 1.857V 1.857V 1.881V 3.333V 3.357V 5.000V 5.024V 5.286V 5.310V 5.310V 5.333V 5.929V 5.952V INPUT VOLTAGE VIN2 (+3.3V) 15.7mV 1.194V 1.210V 1.210V 1.226V 1.226V 1.242V 2.200V 2.216V 3.300V 3.3157V 3.486V 3.504V 3.504V 3.521V 3.913V 3.929V INPUT VOLTAGE VIN3 (+2.5V) 11.9mV 0.905V 0.917V 0.917V 0.929V 0.929V 0.941V 1.250V 1.262V 2.500V 2.512V 2.643V 2.655V 2.655V 2.667V 2.964V 2.976V
Table Address (ADD[1:0])
ADD0 High-Z High-Z High-Z ADD1 High-Z High-Z High-Z ADDRESS 0011 0000 0011 0010 0011 0100 0101 0010 0101 0100 0101 0110 1001 1000 1001 1010 1001 1100
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
Table Command Byte Register
REGISTER RLTS RRTE RCRA RLHN RLLI RRHI RRLS WCRW WLHO WLLM WRHA WRLN RRET1 RRET2 RLET RRT2 RRHL2 RRLL2 RLOL RLOL1 RLOL2 WLOL WROL1 WROL2 WRH2 WRL2 WV0HL WV0LL WV1HL WV1LL WV2HL WV2LL WV3HL WV3LL RV0HL RV0LL ADDRESS STATE 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0111 1111 1100 1001 0111 1111 1100 1001 0000 0000 0000 0000 0000 0000 0000 0000 0111 1111 1100 1001 0111 1111 0111 1111 0111 1111 1101 0011 1010 1101 FUNCTION Read Internal Temperature Read External Temperature Read Status Byte; Note Read Configuration Byte Read Conversion Rate Byte Read Internal ALERT High Limit Read Internal ALERT Limit Read External Temperature ALERT High Limit Read External Temperature ALERT Limit Write Configuration Byte Write Conversion Rate Control Byte Write Internal ALERT High Limit Write Internal ALERT Limit Write External Temperature ALERT High Limit Write External Temperature ALERT Limit Read External Extended Temperature Read External Extended Temperature Read Internal Extended Temperature Read External Temperature Read External Temperature ALERT High Limit Read External Temperature ALERT Limit Read Internal OVERT Limit Read External OVERT Limit Read External OVERT Limit Write Internal OVERT Limit Write External OVERT Limit Write External OVERT Limit Write External Temperature ALERT High Limit Write External Temperature ALERT Limit Write (VIN2) ALERT High Limit MAX6655 (MAX6656) Write (VIN2) ALERT Limit MAX6655 (MAX6656) Write VIN1 ALERT High Limit Write VIN1 ALERT Limit Write VIN2 (VCC) ALERT High Limit MAX6655 (MAX6656) Write VIN2 (VCC) ALERT Limit MAX6655 (MAX6656) Write VIN3 ALERT High Limit Write VIN3 ALERT Limit Read (VIN2) ALERT High Limit MAX6655 (MAX6656) Read (VIN2) ALERT Limit MAX6655 (MAX6656)
MAX6655/MAX6656
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Table Command Byte Register (continued)
REGISTER RV1HL RV1LL RV2HL RV2LL RV3HL RV3LL RSL2 RCL2 WCA2 RDID RDRV ADDRESS STATE 1101 0011 1010 1101 1101 0011 1010 1101 1101 0011 1010 1101 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 1010 0100 1101 FUNCTION Read VIN1 ALERT High Limit Read VIN1 ALERT Limit Read VIN2 (VCC) ALERT High Limit MAX6655 (MAX6656) Read VIN2 (VCC) ALERT Limit MAX6655 (MAX6656) Read VIN3 ALERT High Limit Read VIN3 ALERT Limit Read (VIN2) MAX6655 (MAX6656) Read VIN1 Read VIN2 (VCC) MAX6655 (MAX6656) Read VIN3 Read Status Byte Read Configuration Byte Write Configuration Byte Read Device Read Manufacture
Note Upon application power, begins converting. Status Byte register indicates conversion progress. Status Byte value during conversions value between conversions. Therefore, power-on, Status Byte alternates between 80h.
Table Configuration Byte Assignments
(MSB) NAME Mask RUN/STOP Mask Remote Temperature Mask Remote Temperature Mask VIN3 Mask VIN2 Mask VIN1 Mask STATE FUNCTION Masks ALERT interrupts high. Standby mode control bit; high, device immediately stops converting enters standby mode. low, device enters normal conversion mode. High masks OVERT ALERT interrupts remote-diode High masks OVERT ALERT interrupts remote-diode High masks ALERT interrupts VIN3. High masks ALERT interrupts VIN2 (VCC) MAX6655 (MAX6656). High masks ALERT interrupts VIN1. High masks ALERT interrupts (VIN2) MAX6655 (MAX6656).
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Table Configuration Byte 2-Bit Assignments
NAME Disable Remote Temperature Measurement Disable Remote Temperature Measurement Disable Internal Temperature Measurement Disable VIN3 Measurement Disable VIN2 Measurement Disable VIN1 Measurement Disable Measurement Reserved STATE FUNCTION
(MSB)
high, remote temperature measurement disabled.
high, remote temperature measurement disabled.
high, internal temperature measurement disabled.
high, input voltage VIN3 measurement disabled. high, input voltage VIN2 (VCC) measurement disabled MAX6655 (MAX6656). high, input voltage VIN1 measurement disabled. high, input voltage (VIN2) measurement disabled MAX6655 (MAX6656). Reserved future use.
Table Status Byte 1-Bit Assignments
(MSB) NAME BUSY LHIGH LLOW RHIGH RLOW DODS1 R2HIGH R2LOW STATE FUNCTION busy converting when high. Internal high-temperature ALERT tripped when high; cleared readout entire Status Byte. Internal low-temperature ALERT tripped when high; cleared readout entire Status Byte. External high-temperature ALERT tripped when high; cleared readout entire Status Byte. External low-temperature ALERT tripped when high; cleared readout entire Status Byte. high indicates external diode open/short. External high-temperature ALERT tripped when high; cleared readout entire Status Byte. External low-temperature ALERT tripped when high; cleared readout entire Status Byte.
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Table Status Byte 2-Bit Assignments
7(MSB) NAME DODS2 VCCA STATE FUNCTION Internal temperature exceeded OVERT limit. Clear falling below limit. External temperature exceeded OVERT limit. Clear falling below limit. External temperature exceeded OVERT limit. Clear falling below limit. high indicates external diode open short. VIN3 window ALERT tripped when high; cleared reading Status Byte. VIN2 window ALERT tripped when high; cleared reading Status Byte. VIN1 window ALERT tripped when high; cleared reading Status Byte. window ALERT tripped when high; cleared reading Status Byte.
Table Remote-Sensor Transistor Manufacturers
MANUFACTURER Central Semiconductor (USA) Fairchild Semiconductor (USA) Infineon (Germany) Semiconductor (USA) Rohm Semiconductor (Japan) Zetex (England) MODEL NUMBER CMPT3906 MMBT3906 SMBT3906 MMBT3906 SST3906 FMMT3906CT-ND
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors
Typical Application Circuit
MAX6655/MAX6656
2.5V DXP1 DXN1 3.3V 2.5V VIN1 VIN2 VIN3 DXP2 MAX6655 MAX6656 SMBCLK SMBDATA ALERT OVERT ADD0 ADD1 DXN2 2N3906 2200pF SYSTEM SHUTDOWN 0.1µF SMBus/I2C CONTROLLER
Functional Diagram
MAX6655/MAX6656
VIN1 VIN2 VIN3 INPUT VOLTAGE SCALING MULTIPLEXER DATA CONTROL LOGIC
DXP1 DXN1
TEMPERATURE SENSOR
VOLTAGE REFERENCE
SMBus/I2CCOMPATIBLE INTERFACE
SMBDATA SMBCLK ALERT OVERT
DXP2 DXN2
ADD0 ADD1
Dual Remote/Local Temperature Sensors Four-Channel Voltage Monitors MAX6655/MAX6656
Package Information
(The package drawing(s) this data sheet reflect most current specifications. latest package outline information www.maxim-ic.com/packages.)
QSOP.EPS
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
21-0055
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
_Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 408-737-7600 2006 Maxim Integrated Products Printed registered trademark Maxim Integrated Products, Inc.
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