19-3003; 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. Two
open-drain outputs, OVERT and ALERT, assert corresponding 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 temperature data and programming the alarm thresholds.
The MAX6622 is specified for a -40°C to +125°C operating temperature range and is available in a 16-pin
TSSOP package.
Features
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
Four Thermal-Diode Inputs
Local Temperature Sensor
1°C Remote Temperature Accuracy (+60°C to +100°C)
Temperature Monitoring Begins at POR for FailSafe 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
Ordering Information
Notebook Computers
PINSLAVE
PKG
PACKAGE
ADDRESS
CODE
MAX6622UE9A+ 16 TSSOP
1001 101
U16-1
Note: This device is specified over the -40°C to +125°C
temperature range.
Workstations
+Denotes lead-free package.
Applications
Desktop Computers
PART
Servers
SMBus is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.
Typical Application Circuit
+3.3V
CPU
1
DXP1
GND 16
4.7kΩ
EACH
2
DXN1
SMBCLK 15
CLK
3
DXP2
MAX6622 SMBDATA 14
4
DXN2
ALERT 13
5
DXP3
VCC 12
6
DXN3
OVERT 11
7
DXP4
N.C. 10
8
DXN4
2200pF
DATA
2200pF
INTERRUPT
TO μP
0.1μF
2200pF
TO SYSTEM
SHUTDOWN
2200pF
STBY
9
________________________________________________________________ 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.
1
MAX6622
General Description
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 .......................................................................±1mA
Continuous Power Dissipation (TA = +70°C)
16-Pin TSSOP
(derate 11.1mW/°C above +70°C)..............................888.9mW
Junction-to-Case Thermal Resistance (θJC) (Note A)
16-Pin TSSOP ..............................................................27°C/W
Junction-to-Ambient Thermal Resistance (θJA) (Note A)
16-Pin TSSOP...............................................................90°C/W
ESD Protection (all pins, Human Body Model) ................±2000V
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note A: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a
4-layer board. For detailed information on package thermal considerations, refer to Application Note 4083 available
at www.maxim-ic.com/thermal-tutorial.
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 = +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
Supply Voltage
SYMBOL
CONDITIONS
VCC
MIN
TYP
3.0
Software Standby Supply Current
ISS
SMBus static
30
Operating Current
ICC
During conversion
500
Channel 1 only
11
Other diode channels
8
Temperature Resolution
Remote Temperature Accuracy
VCC = 3.3V
Local Temperature Accuracy
VCC = 3.3V
UNITS
5.5
V
1000
µA
µA
Bits
TA = TRJ = +60°C to +100°C
-1.0
+1.0
TA = TRJ = 0°C to +125°C
-3.0
+3.0
TA = +60°C to +100°C
-4.4
-0.4
TA = 0°C to +125°C
-6.1
-0.1
Supply Sensitivity of Temperature
Accuracy
±0.2
Remote Channel 1 Conversion
Time
tCONV1
Remote Channels 2 Through 4
Conversion Time
tCONV_
Remote-Diode Source Current
IRJ
Undervoltage-Lockout Threshold
MAX
UVLO
95
125
156
Resistance cancellation on
190
250
312
95
125
156
High level
80
100
120
Low level
8
10
12
Falling edge of VCC disables ADC
2.30
2.80
2.95
VCC falling edge
1.2
2.0
90
Power-On-Reset (POR) Threshold
POR Threshold Hysteresis
C
o
o
Resistance cancellation off
Undervoltage-Lockout Hysteresis
o
C
C/V
ms
ms
µA
V
mV
2.5
90
V
mV
ALERT, OVERT
Output Low Voltage
VOL
ISINK = 1mA
0.3
ISINK = 6mA
0.5
Output Leakage Current
2
_______________________________________________________________________________________
1
V
µA
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
0.3
5
µA
V
pF
SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2)
Serial-Clock Frequency
Bus Free Time Between STOP
and START Condition
fSCL
tBUF
START Condition Setup Time
Repeat START Condition Setup
Time
START Condition Hold Time
STOP Condition Setup Time
tSU:STA
tHD:STA
tSU:STO
Clock Low Period
tLOW
Clock High Period
tHIGH
Data Hold Time
tHD:DAT
Data Setup Time
tSU:DAT
Receive SCL/SDA Rise Time
tR
Receive SCL/SDA Fall Time
tF
Pulse Width of Spike Suppressed
tSP
SMBus Timeout
Note 1:
Note 2:
Note 3:
Note 4:
tTIMEOUT
(Note 3)
400
fSCL = 100kHz
4.7
fSCL = 400kHz
1.6
fSCL = 100kHz
4.7
fSCL = 400kHz
0.6
90% of SCL to 90% of SDA,
fSCL = 100kHz
0.6
90% of SCL to 90% of SDA,
fSCL = 400kHz
0.6
10% of SDA to 90% of SCL
0.6
90% of SCL to 90% of SDA,
fSCL = 100kHz
4
90% of SCL to 90% of SDA,
fSCL = 400kHz
0.6
10% to 10%, fSCL = 100kHz
1.3
10% to 10%, fSCL = 400kHz
1.3
90% to 90%
0.6
fSCL = 100kHz
300
µs
µs
µs
µs
µs
µs
µs
fSCL = 400kHz (Note 4)
900
fSCL = 100kHz
250
fSCL = 400kHz
100
1
fSCL = 400kHz
0.3
0
25
ns
ns
fSCL = 100kHz
SDA low period for interface reset
kHz
37
µs
300
ns
50
ns
45
ms
All parameters are tested at TA = +85°C. Specifications over temperature are guaranteed by design.
Timing specifications are guaranteed by design.
The serial interface resets when SCL is low for more than tTIMEOUT.
A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL’s falling edge.
_______________________________________________________________________________________
3
MAX6622
ELECTRICAL CHARACTERISTICS (continued)
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. COMMON-MODE NOISE FREQUENCY
5
MAX6622 toc06
100mVP-P
3
4
TEMPERATURE ERROR (°C)
TEMPERATURE ERROR (°C)
50
REMOTE-DIODE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
4
TEMPERATURE ERROR (°C)
25
2
1
0
-1
-2
2
1
0
-1
-2
-3
-4
-4
0.01
0.1
FREQUENCY (MHz)
1
100mVP-P
3
-3
-5
0.001
100
REMOTE-DIODE TEMPERATURE (°C)
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
4
0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
5
-2
-4
3.3
5.3
-1
MAX6622 toc05
3.8
0
MAX6622 toc07
3.3
1
-3
325
0
4
2
TEMPERATURE ERROR (°C)
SUPPLY CURRENT (μA)
355
8
3
MAX6622 toc02
360
MAX6622 toc01
12
11
10
9
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SOFTWARE STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
STANDBY SUPPLY CURRENT (μA)
MAX6622
5-Channel Precision Temperature Monitor
-5
0.001
0.01
0.1
1
FREQUENCY (MHz)
_______________________________________________________________________________________
10
125
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
0.1
1
10
1
FREQUENCY (MHz)
10
100
DXP-DXN CAPACITANCE (nF)
Pin Description
PIN
NAME
FUNCTION
1
DXP1
Combined Current Source and A/D Positive Input for Channel 1 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 DXP1 and DXN1 for noise filtering.
2
DXN1
Cathode Input for Channel 1 Remote Diode. Connect the cathode of the channel 1 remote-diodeconnected transistor to DXN1. Internally connected to GND.
3
DXP2
Combined Current Source and A/D Positive Input for Channel 2 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 DXP2 and DXN2 for noise filtering.
4
DXN2
Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diodeconnected transistor to DXN2.
5
DXP3
Combined Current Source and A/D Positive Input for Channel 3 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 DXP3 and DXN3 for noise filtering.
6
DXN3
Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 3 remote-diodeconnected transistor to DXN3.
_______________________________________________________________________________________
5
MAX6622
Typical Operating Characteristics (continued)
(VCC = 3.3V, VSTBY = VCC, TA = +25°C, unless otherwise noted.)
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. Connect the cathode of the channel 4 remote-diodeconnected transistor to DXN4.
9
STBY
Standby Input. Drive STBY logic-low to place the MAX6622 in hardware standby mode, or logic-high
for normal operation. Temperature and threshold data are retained in standby mode.
10
N.C.
No Connection. Must be connected to ground.
11
OVERT
12
VCC
13
ALERT
14
SMBDATA
15
SMBCLK
16
GND
Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of
channels 1 and 4 exceed the programmed threshold limit.
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
SMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of
any channel exceeds the programmed ALERT threshold.
SMBus Serial-Data Input/Output. Connect to a pullup resistor.
SMBus Serial-Clock Input. Connect to a pullup resistor.
Ground
Detailed Description
The MAX6622 is a precision multichannel temperature
monitor that features one local and four remote temperature-sensing channels with a programmable alert
threshold for each temperature channel and a programmable overtemperature threshold for channels 1 and 4
(see Figure 1). Communication with the MAX6622 is
achieved through the SMBus serial interface and a
dedicated alert output. The alarm outputs, OVERT and
ALERT, assert if the software-programmed temperature
thresholds are exceeded. ALERT typically serves as an
interrupt, while OVERT can be connected to a fan, system shutdown, or other thermal-management circuitry.
ADC Conversion Sequence
In the default conversion mode, the MAX6622 starts the
conversion sequence by measuring the temperature on
channel 1, followed by 2, 3, local channel, and 4. The
conversion result for each active channel is stored in
the corresponding temperature data register.
In some systems, one of the remote thermal diodes may
be monitoring a location that experiences temperature
changes that occur much more rapidly than in the other
channels. If faster temperature changes must be monitored in one of the temperature channels, the MAX6622
6
allows channel 1 to be monitored at a faster rate than
the other channels. In this mode (set by writing a 1 to
bit 4 of the configuration 1 register), measurements of
channel 1 alternate with measurements of the other
channels. The sequence becomes channel 1, channel
2, channel 1, channel 3, channel 1, etc. Note that the
time required to measure all five channels is considerably greater in this mode than in the default mode.
Low-Power Standby Mode
Enter software standby mode by setting the STOP bit to
1 in the configuration 1 register. Enter hardware standby
by pulling STBY low. Software standby mode disables
the ADC and reduces the supply current to approximately 30µA. Hardware standby mode halts the ADC clock,
but the supply current is approximately 350µA. During
either software or hardware standby, data is retained in
memory, and the SMBus interface is active and listening
for SMBus commands. The timeout is enabled if a
START condition is recognized on SMBus. Activity on the
SMBus causes the supply current to increase. If a standby command is received while a conversion is in
progress, the conversion cycle is interrupted, and the
temperature registers are not updated. The previous
data is not changed and remains available.
_______________________________________________________________________________________
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. Internal Block Diagram
SMBus Digital Interface
From a software perspective, the MAX6622 appears as
a series of 8-bit registers that contain temperature measurement data, alarm threshold values, and control bits.
A standard SMBus-compatible, 2-wire serial interface is
used to read temperature data and write control bits
and alarm threshold data. The same SMBus slave
address also provides access to all functions.
The MAX6622 employs four standard SMBus protocols:
write byte, read byte, send byte, and receive byte
(Figure 2). The shorter receive byte protocol allows
quicker transfers, provided that the correct data register was previously selected by a read byte instruction.
Use caution with the shorter protocols in multimaster
systems, since a second master could overwrite the
command byte without informing the first master. Figure
3 is the SMBus write timing diagram and Figure 4 is the
SMBus read timing diagram.
The remote diode 1 measurement channel provides 11
bits of data (1 LSB = +0.125°C). All other temperaturemeasurement channels provide 8 bits of temperature
data (1 LSB = +1°C). The 8 most significant bits (MSBs)
can be read from the local temperature and remote
temperature registers. The remaining 3 bits for remote
diode 1 can be read from the extended temperature
register. If extended resolution is desired, the extended
resolution register should be read first. This prevents
the most significant bits from being overwritten by new
_______________________________________________________________________________________
7
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 REGISTER YOU
ARE READING
///
P
8 bits
SLAVE ADDRESS: REPEATED
DUE TO CHANGE IN DATAFLOW DIRECTION
DATA BYTE: READS FROM
THE REGISTER SET BY THE
COMMAND BYTE
Receive Byte Format
ACK
COMMAND
ACK
P
S
ADDRESS
7 bits
8 bits
RD
ACK
DATA
///
P
8 bits
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
COMMAND BYTE: SENDS COMMAND WITH NO DATA, USUALLY
USED FOR ONE-SHOT COMMAND
S = START CONDITION.
P = STOP CONDITION.
ACK
7 bits
Send Byte Format
ADDRESS
ADDRESS
8 bits
SLAVE ADDRESS: EQUIVALENT
TO CHIP-SELECT LINE
S
S
SHADED = SLAVE TRANSMISSION.
/// = NOT ACKNOWLEDGED.
Figure 2. SMBus Protocols
Table 1. Main Temperature Register
(High-Byte) Data Format
TEMP (°C)
DIGITAL OUTPUT
TEMP (°C)
DIGITAL OUTPUT
> +127
0111 1111
0
000X XXXX
+127
0111 1111
+0.125
001X XXXX
+126
0111 1110
+0.250
010X XXXX
+25
0001 1001
+0.375
011X XXXX
0
0000 0000
+0.500
100X XXXX
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