Datasheet

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General Description

The MAX6622 precision multichannel temperature sen-

sor monitors its own temperature and the temperatures

of up to four external diode-connected transistors. All

temperature channels have programmable alert thresh-

olds. Channels 1 and 4 also have programmable

overtemperature thresholds. When the measured tem-

perature of a channel exceeds the respective thresh-

old, a status bit is set in one of the status registers. Two

open-drain outputs, OVERT and ALERT, assert corre-

sponding to these bits in the status register.

The 2-wire serial interface supports the standard system

management bus (SMBus™) protocols: write byte, read

byte, send byte, and receive byte for reading the tem-

perature data and programming the alarm thresholds.

The MAX6622 is specified for a -40°C to +125°C oper-

ating temperature range and is available in a 16-pin

TSSOP package.

Applications

Desktop Computers

Notebook Computers

Workstations

Servers

Features

♦ Four Thermal-Diode Inputs

♦ Local Temperature Sensor

♦ 1°C Remote Temperature Accuracy (+60°C to +100°C)

♦ Temperature Monitoring Begins at POR for Fail-

Safe System Protection

♦ ALERT and OVERT Outputs for Interrupts,

Throttling, and Shutdown

♦ STBY Input for Hardware Standby Mode

♦ Small, 16-Pin TSSOP Package

♦ 2-Wire SMBus Interface

♦ Penryn CPU-Compatible

♦ Pin- and Register-Compatible with MAX6602

MAX6622

5-Channel Precision Temperature Monitor

________________________________________________________________

Maxim Integrated Products

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

GND

SMBCLK

SMBDATA

DXN2

DXP2

DXN1

DXP1

N.C.

STBYDXN4

DXP4

DXN3

DXP3

MAX6622

ALERT

OVERT

2200pF

CPU

0.1μF

TO SYSTEM

SHUTDOWN

INTERRUPT

TO μP

DATA

CLK

4.7kΩ

EACH

+3.3V

Typical Application Circuit

19-3003; Rev 0; 12/07

PART

PIN-

PACKAGE

SLAVE

ADDRESS

PKG

CODE

MAX6622UE9A+ 16 TSSOP 1001 101 U16-1

SMBus is a trademark of Intel Corp.

Note: This device is specified over the -40°C to +125°C

temperature range.

Denotes lead-free package.

Pin Configuration appears at end of data sheet.

Summary of content (18 pages)

PAGE 1
9-3003; Rev 0; 12/07 5-Channel Precision Temperature Monitor The MAX6622 precision multichannel temperature sensor monitors its own temperature and the temperatures of up to four external diode-connected transistors. All temperature channels have programmable alert thresholds. Channels 1 and 4 also have programmable overtemperature thresholds. When the measured temperature of a channel exceeds the respective threshold, a status bit is set in one of the status registers.
PAGE 2
MAX6622 5-Channel Precision Temperature Monitor ABSOLUTE MAXIMUM RATINGS VCC, SMBCLK, SMBDATA, ALERT, OVERT, STBY to GND .......................................................-0.3V to +6V DXP_ to GND..............................................-0.3V to (VCC + 0.3V) DXN2, DXN3, DXN4 to GND .................................-0.3V to +0.8V SMBDATA, ALERT, OVERT Current....................-1mA to +50mA DXN Current .......................................................................
PAGE 3
5-Channel Precision Temperature Monitor (VCC = +3.0V to +5.5V, VSTBY = VCC, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.8 V SMBus INTERFACE (SCL, SDA), STBY Logic Input Low Voltage Logic Input High Voltage VIL VIH VCC = 3.0V 2.2 VCC = 5.0V 2.4 Input Leakage Current V -1 Output Low Voltage VOL Input Capacitance CIN +1 ISINK = 6mA 0.
PAGE 4
Typical Operating Characteristics (VCC = 3.3V, VSTBY = VCC, TA = +25°C, unless otherwise noted.) 7 6 5 4 350 345 340 335 330 3 2 1 320 4.3 4.8 3.8 4.3 4.8 5.3 5 MAX6622 toc04 MAX6622 toc03 75 2 1 0 -1 -2 100mVP-P 4 TEMPERATURE ERROR (°C) 3 3 2 1 0 -1 -2 -3 -3 -4 -4 -5 0 25 50 75 100 0.1 125 1 DIE TEMPERATURE (°C) FREQUENCY (MHz) LOCAL TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY REMOTE TEMPERATURE ERROR vs.
PAGE 5
-Channel Precision Temperature Monitor REMOTE TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY 0 3 2 1 0 -1 -2 -3 MAX6622 toc09 100mVP-P -0.5 TEMPERATURE ERROR (°C) TEMPERATURE ERROR (°C) 4 MAX6622 toc08 5 TEMPERATURE ERROR vs. DXP-DXN CAPACITANCE -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 -4 -4.5 -5 0.001 -5.0 0.01 0.
PAGE 6
5-Channel Precision Temperature Monitor MAX6622 Pin Description (continued) PIN NAME FUNCTION 7 DXP4 Combined Current Source and A/D Positive Input for Channel 4 Remote Diode. Connect to the anode of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to VCC if no remote diode is used. Place a 2200pF capacitor between DXP4 and DXN4 for noise filtering. 8 DXN4 Cathode Input for Channel 4 Remote Diode.
PAGE 7
5-Channel Precision Temperature Monitor MAX6622 VCC MAX6622 DXP1 10/100μA ADC ALARM ALU DXN1 OVERT AVERT DXP2 DXN2 COUNT INPUT BUFFER DXP3 REGISTER BANK COMMAND BYTE COUNTER REMOTE TEMPERATURES DXN3 LOCAL TEMPERATURES REF DXP4 ALERT THRESHOLD OVERT THRESHOLD DXN4 ALERT RESPONSE ADDRESS SMBus INTERFACE STBY SMBCLK SMBDATA Figure 1.
PAGE 8
MAX6622 5-Channel Precision Temperature Monitor 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 TO WHICH REGISTER YOU ARE WRITING 1 DATA BYTE: DATA GOES INTO THE REGISTER SET BY THE COMMAND BYTE (TO SET THRESHOLDS, CONFIGURATION MASKS, AND SAMPLING RATE) Read Byte Format S ADDRESS WR ACK 7 bits COMMAND ACK WR 7 bits RD DATA COMMAND BYTE: SELECTS FROM WHICH REGI
PAGE 9
5-Channel Precision Temperature Monitor B tLOW C D E F G H tHIGH I J K L MAX6622 A M SMBCLK SMBDATA tSU:STA tHD:STA tSU:STO 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 F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE tBUF I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE
PAGE 10
MAX6622 5-Channel Precision Temperature Monitor ALERT Response Address The SMBus alert response interrupt pointer provides quick fault identification for simple slave devices that lack the complex logic needed to be a bus master. Upon receiving an interrupt signal, the host master can broadcast a receive byte transmission to the alert response slave address (see the Slave Address section). Then, any slave device that generated an interrupt attempts to identify itself by putting its own address on the bus.
PAGE 11
5-Channel Precision Temperature Monitor MAX6622 Table 3.
PAGE 12
MAX6622 5-Channel Precision Temperature Monitor Table 4. Configuration 1 Register BIT NAME POR STATE 7 (MSB) STOP 0 Standby Mode Control Bit. If STOP is set to logic 1, the MAX6622 stops converting and enters standby mode. 6 POR 0 Reset Bit. Set to logic 1 to put the device into its power-on state. This bit is selfclearing. 5 TIMEOUT 0 Timeout Enable Bit. Set to logic 0 to enable SMBus timeout. 4 Fast remote 1 0 Channel 1 Fast Conversion Bit.
PAGE 13
5-Channel Precision Temperature Monitor BIT NAME POR STATE 7 (MSB) Reserved 0 — 6 Local ALERT 0 Local Channel High-Alert Bit. This bit is set to logic 1 when the local temperature exceeds the temperature threshold limit in the local ALERT highlimit register. 5 Reserved 0 — 4 Reserved 0 — 3 Remote 4 ALERT 0 Channel 4 Remote-Diode High-Alert Bit.
PAGE 14
MAX6622 5-Channel Precision Temperature Monitor Table 9. Status 3 Register NAME POR STATE 7 (MSB) Reserved 0 — 6 Reserved 0 Not Used. 0 at POR, then 1. 5 Reserved 0 Not Used. 0 at POR, then 1. 4 Diode fault 4 0 Channel 4 Remote-Diode Fault Bit. This bit is set to 1 when DXP4 and DXN4 are open circuit or when DXP4 is connected to VCC. 3 Diode fault 3 0 Channel 3 Remote-Diode Fault Bit. This bit is set to 1 when DXP3 and DXN3 are open circuit or when DXP3 is connected to VCC.
PAGE 15
5-Channel Precision Temperature Monitor Unused Diode Channels If one or more of the remote diode channels is not needed, the DXP and DXN inputs for that channel should either be unconnected, or the DXP input should be connected to VCC. The status register indicates a diode "fault" for this channel and the channel is ignored during the temperature-measurement sequence.
PAGE 16
MAX6622 5-Channel Precision Temperature Monitor Slave Address The slave address of the MAX6622 is 9Ah or 1001 101. PCB Layout Follow these guidelines to reduce the measurement error when measuring remote temperature: 1) Place the MAX6622 as close as is practical to the remote diode. In noisy environments, such as a computer motherboard, this distance can be 4in to 8in (typ). This length can be increased if the worst noise sources are avoided.
PAGE 17
5-Channel Precision Temperature Monitor Chip Information PROCESS: BiCMOS TOP VIEW + DXP1 1 16 GND DXN1 2 15 SMBCLK DXP2 3 MAX6622 14 SMBDATA DXN2 4 13 ALERT DXP3 5 12 VCC DXN3 6 11 OVERT DXP4 7 10 N.C.
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.) TSSOP4.40mm.EPS MAX6622 5-Channel Precision Temperature Monitor PACKAGE OUTLINE, TSSOP 4.40mm BODY 21-0066 I 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.