Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsMAX6655MEE+

General Description

The MAX6655/MAX6656 are precise voltage and tem-

perature monitors. The digital thermometer reports the

temperature of two remote sensors and its own die tem-

perature. The remote sensors are diode-connected

transistors—typically a low-cost, easily mounted

2N3906 PNP type—that replace conventional thermis-

tors or thermocouples. Remote accuracy is ±1°C for

multiple transistor manufacturers with no calibration

necessary. The remote channels can also measure the

die temperature of other ICs, such as microprocessors,

that contain a substrate-connected PNP with its collec-

tor grounded and its base and emitter available for tem-

perature-sensing purposes. The temperature is

digitized with 11-bit resolution.

The MAX6655/MAX6656 also measure their own supply

voltage and three external voltages with 8-bit resolution.

Each voltage input’s sensitivity is set to give approxi-

mately 3/4-scale output code when the input voltage is

at its nominal value. The MAX6655 operates at +5V

supply and its second voltage monitor is 3.3V. The

MAX6656 operates on a +3.3V supply and its second

voltage monitor is 5V.

The 2-wire serial interface accepts standard SMBus™

Write Byte, Read Byte, Send Byte, and Receive Byte

commands to program the alarm thresholds and to read

data. The MAX6655/MAX6656 also provide SMBus alert

response and timeout functions. The MAX6655/MAX6656

measure automatically and autonomously, with the con-

version rate programmable. The adjustable rate allows

the user to control the supply current.

In addition to the SMBus ALERT output, the MAX6655/

MAX6656 feature an OVERT output, which is used as a

temperature reset that remains active only while the

temperature is above the maximum temperature limit.

The OVERT output is optimal for fan control or for sys-

tem shutdown.

Features

♦ Three Temperature Channels

Two Remote PN Junctions

One Local Sensor

♦ Four Voltage Channels

+12V, +5V, +3.3V, +2.5V

Three External Monitors

One Internal Supply Monitor

♦ 11-Bit, 0.125°C Resolution

♦ High Accuracy: ±1°C Over +60°C to +100°C

Temperature Range

♦ Programmable Under/Over-Threshold Alarms

♦ Programmable Power-Saving Mode

♦ No Calibration Required

♦ SMBus/I

C-Compatible Interface

♦ OVERT Output for Fan Control and System

Shutdown

MAX6655/MAX6656

Dual Remote/Local Temperature Sensors and

Four-Channel Voltage Monitors

________________________________________________________________ Maxim Integrated Products 1

STBY

SMBCLK

OVERT

SMBDATA

ALERT

IN2

IN1

IN3

TOP VIEW

MAX6655

MAX6656

QSOP

DXP1

DXN1

DXP2

ADD0

ADD1

DXN2

GND

Pin Configuration

Ordering Information

19-2117; Rev 1; 5/06

PART TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX6655MEE -55°C to +125°C

16 QSOP

E16-5

MAX6656MEE -55°C to +125°C

16 QSOP

E16-5

*P,

SMBus is a trademark of Intel Corp.

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.

Typical Application Circuit appears at end of data sheet.

Notebooks

Thin Clients

Servers

Workstations

Communication

Equipment

Desktop PC

Applications

Summary of content (18 pages)

PAGE 1
9-2117; Rev 1; 5/06 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Features The MAX6655/MAX6656 are precise voltage and temperature monitors. The digital thermometer reports the temperature of two remote sensors and its own die temperature. The remote sensors are diode-connected transistors—typically a low-cost, easily mounted 2N3906 PNP type—that replace conventional thermistors or thermocouples.
PAGE 2
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors ABSOLUTE MAXIMUM RATINGS VCC to GND ..............................................................-0.3V to +6V DXN_ to GND ........................................................-0.3V to +0.8V SMBCLK, SMBDATA, ALERT, STBY, OVERT to GND .....................................................-0.3V to +6V VIN1 to GND............................................................-0.3V to +16V VIN2 to GND........................
PAGE 3
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors (VCC = +3.0V to +3.6V for MAX6656, VCC = +4.5V to +5.5V for MAX6655, TA = -55°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V for MAX6656, VCC = +5.0V for MAX6655, TA = +25°C.
PAGE 4
Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) PATH = DXP TO VCC (5V) -10 3 2 1 0 -1 -2 20 MAX6655/MAX6656 toc03 RANDOM SAMPLE 2N3906 4 TEMPERATURE ERROR (°C) PATH = DXP TO GND 0 MAX6655/MAX6656 toc02 10 5 REMOTE TEMPERATURE ERROR (°C) MAX6655/MAX6656 toc01 REMOTE TEMPERATURE ERROR (°C) 20 TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY REMOTE TEMPERATURE ERROR vs. REMOTE-DIODE TEMPERATURE REMOTE TEMPERATURE ERROR vs.
PAGE 5
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors PIN NAME 1 VCC Supply Voltage. +5V for MAX6655; +3.3V for MAX6656. Bypass VCC to GND with a 0.1µF capacitor. FUNCTION 2 DXP1 External Diode 1 Positive Connection. DXP1 is the combined current source and ADC positive input for remote-diode 1. If a remote-sensing junction is not used, connect DXP1 to DXN1. 3 DXN1 External Diode 1 Negative Connection. DXN1 is the combined current sink and ADC negative input for remote-diode 1.
PAGE 6
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Write Byte Format S ADDRESS WR ACK COMMAND 7 bits 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 WR ADDRESS ACK 7 bits COMMAND ACK Slave Address: equ
PAGE 7
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors tLOW B C tHIGH D E F G I H J K L MAX6655/MAX6656 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 SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION F = ACKNOWLEDGE BIT CLOCKED INTO MAS
PAGE 8
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors the T HIGH or T LOW alarms at their POR settings. Similarly, if DXP_ is short circuited to V CC, the ADC reads -1°C for both remote channels, and the ALERT outputs are activated. +3V TO +5.5V Alert Interrupts VCC MAX6655 MAX6656 SMBCLK SMBus SERIAL INTERFACE (TO HOST) SMBDATA TO SYSTEM SHUTDOWN ALERT OVERT DXP2 ADD0 ADD1 DXN2 2N3906 GND 2200pF Figure 4.
PAGE 9
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Configuration Byte Functions Configuration Bytes 1 and 2 (Tables 7 and 8) are used to mask (disable) interrupts, disable temperature and voltage measurements, and put the device in software standby mode. The serial interface can read back the contents of these registers. Status Byte Functions The two Status Byte registers (Tables 9 and 10) indicate which (if any) temperature or voltage thresholds have been exceeded.
PAGE 10
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors places constraints on high-frequency noise rejection. Lay out the PC board carefully with proper external noise filtering for high-accuracy remote measurements in electrically noisy environments. Filter high-frequency electromagnetic interference (EMI) at DXP and DXN with an external 2200pF capacitor connected between the two inputs. This capacitor can be increased to about 3300pF (max), including cable capacitance.
PAGE 11
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Table 3. Extended Resolution Register DATA (RCRA, 04H) WAIT TIME BETWEEN CONVERSION SEQUENCES (s) FRACTIONAL TEMPERATURE (°C) DIGITAL OUTPUT 0 0000 0000 0.125 0010 0000 00h 0 0.250 0100 0000 01h 0.125 0.375 0110 0000 02h 0.250 0.500 1000 0000 03h 0.500 0.625 1010 0000 04h 1.000 0.750 1100 0000 05h 2.000 0.875 1110 0000 06h 4.000 07h 4.000 Table 2.
PAGE 12
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Table 4. Voltage Data Format ADC OUTPUT CODE INPUT VOLTAGE AT VIN1 (+12V) INPUT VOLTAGE AT VIN2 (+5V) OR VCC INPUT VOLTAGE AT VIN2 (+3.3V) OR VCC INPUT VOLTAGE AT VIN3 (+2.5V) LSB weight 57.1mV 23.8mV 15.7mV 11.9mV 64 (≈ 1/4 scale) 4.343V to 4.400V 1.810V to 1.833V 1.194V to 1.210V 0.905V to 0.917V 65 4.400V to 4.457V 1.833V to 1.857V 1.210V to 1.226V 0.917V to 0.929V 66 4.457V to 4.514V 1.
PAGE 13
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors REGISTER RLTS ADDRESS 00h POR STATE 0000 0000 RRTE 01h 0000 0000 MAX6655/MAX6656 Table 6.
PAGE 14
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Table 6.
PAGE 15
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors MAX6655/MAX6656 Table 8. Configuration Byte 2-Bit Assignments BIT NAME POR STATE 7 (MSB) Disable Remote Temperature 1 Measurement 0 If high, the remote temperature 1 measurement is disabled. 6 Disable Remote Temperature 2 Measurement 0 If high, the remote temperature 2 measurement is disabled. 5 Disable Internal Temperature Measurement 0 If high, the internal temperature measurement is disabled.
PAGE 16
MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors Table 10. Status Byte 2-Bit Assignments BIT NAME POR STATE FUNCTION 7(MSB) LO 0 Internal temperature has exceeded OVERT limit. Clear by falling below limit. 6 R1O 0 External temperature 1 has exceeded OVERT limit. Clear by falling below limit. 5 R2O 0 External temperature 2 has exceeded OVERT limit. Clear by falling below limit. 4 DODS2 0 A high indicates external diode 2 open or short.
PAGE 17
Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors 2.5V VCC CPU VCC DXP1 TO 12V TO 3.3V OR 5V TO 2.5V 0.
PAGE 18
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.) QSOP.EPS MAX6655/MAX6656 Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 F 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.