MAX6697EP99+ [MAXIM]
Serial Switch/Digital Sensor, 0.150 INCH, 0.025 INCH PITCH, ROHS COMPLIANT, MO-137AD, QSOP-20;
| 型号： | MAX6697EP99+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Serial Switch/Digital Sensor, 0.150 INCH, 0.025 INCH PITCH, ROHS COMPLIANT, MO-137AD, QSOP-20 输出元件 传感器 换能器 |
| 文件： | 总18页 (文件大小：193K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3477; Rev 3; 5/09
7-Channel Precision Temperature Monitor
General Description
Features
The MAX6697 precision multichannel temperature sen-
sor monitors its own temperature and the temperatures
of up to six external diode-connected transistors. All
temperature channels have programmable alert thresh-
olds. Channels 1, 4, 5, and 6 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.
♦ Six 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
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.
♦ Small 20-Pin QSOP and 20-Pin TSSOP Packages
♦ 2-Wire SMBus Interface
The MAX6697 is specified for an operating temperature
range of -40°C to +125°C and is available in 20-pin
QSOP and 20-pin TSSOP packages.
Ordering Information
PART
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
20 QSOP
Applications
MAX6697EP_ _
MAX6697UP_ _
Desktop Computers
Notebook Computers
Workstations
20 TSSOP
*See the Slave Address section.
Servers
Pin Configuration appears at end of data sheet.
SMBus is a trademark of Intel Corp.
Typical Application Circuit
CPU
DXP
+3.3V
4.7kΩ
EACH
1
2
3
4
5
6
7
8
20
19
18
17
16
15
14
13
DXP1
DXN1
DXP2
DXN2
DXP3
DXN3
DXP4
DXN4
GND
SMBCLK
SMBDATA
ALERT
2200pF
2200pF
2200pF
2200pF
2200pF
MAX6697
CLK
DXN
DATA
INTERRUPT
TO μP
V
CC
0.1μF
OVERT
TO SYSTEM
SHUTDOWN
NC1
NC2
GPU
DXP
9
12
11
DXP5
DXN5
DXP6
DXN6
2200pF
10
DXN
________________________________________________________________ Maxim Integrated Products
1
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.
7-Channel Precision Temperature Monitor
ABSOLUTE MAXIMUM RATINGS
20-Pin TSSOP
V
CC
, SCK, SDA, ALERT, OVERT to GND ................-0.3V to +6V
(derate 11.0mW/°C above +70°C)..................879.1mW(U20-2)
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
DXP_ to GND..............................................-0.3V to (V
+ 0.3V)
CC
DXN_ to GND ........................................................-0.3V to +0.8V
SDA, ALERT, OVERT Current .............................-1mA to +50mA
DXN Current ....................................................................... 1mA
Continuous Power Dissipation (T = +70°C)
A
20-Pin QSOP
(derate 9.1mW/°C above +70°C)......................727.3mW(E20-1)
MAX697
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
(V
CC
= +3.0V to +5.5V, T = -40°C to +125°C, unless otherwise noted. Typical values are at V
= +3.3V and T = +25°C.) (Note 1)
CC A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
Supply Voltage
V
3.0
5.5
CC
SS
Standby Supply Current
Operating Current
I
SMBus static
30
500
11
8
µA
I
During conversion
Channel 1 only
1000
µA
CC
Temperature Resolution
Bits
oC
Other diode channels
T
T
= T = +60°C to +100°C
-1.0
-3.0
+1.0
+3.0
A
A
RJ
= T = 0°C to +125°C
RJ
Remote Temperature Accuracy
Local Temperature Accuracy
V
V
= 3.3V
= 3.3V
CC
CC
DXN_ grounded,
2.5
T
= T = 0°C to +85°C
A
RJ
T
T
= +60°C to +100°C
= 0°C to +125°C
-2.0
-3.0
+2.0
+3.0
A
A
oC
oC/V
ms
ms
µA
Supply Sensitivity of Temperature
Accuracy
0.2
Resistance cancellation on
Resistance cancellation off
95
125
250
156
312
Remote Channel 1 Conversion
Time
t
CONV1
190
Remote Channels 2 Through 6
Conversion Time
t
95
125
156
CONV_
High level
Low level
80
8
100
10
120
12
Remote-Diode Source Current
I
RJ
Undervoltage-Lockout Threshold
Undervoltage-Lockout Hysteresis
Power-On Reset (POR) Threshold
POR Threshold Hysteresis
ALERT, OVERT
UVLO
Falling edge of V disables ADC
2.30
2.80
90
2.95
V
CC
mV
V
V
falling edge
1.2
2.0
90
2.5
CC
mV
I
I
= 1mA
= 6mA
0.3
0.5
1
SINK
SINK
Output Low Voltage
V
V
OL
Output Leakage Current
µA
2
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, T = -40°C to +125°C, unless otherwise noted. Typical values are at V
= +3.3V and T = +25°C.) (Note 1)
CC A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SMBus INTERFACE (SCL, SDA)
Logic-Input Low Voltage
V
0.8
V
V
IL
V
V
= 3.0V
= 5.0V
2.2
2.4
-1
CC
CC
Logic-Input High Voltage
V
IH
V
Input Leakage Current
Output Low Voltage
Input Capacitance
+1
µA
V
V
I
= 6mA
0.3
OL
SINK
C
5
pF
IN
SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2)
Serial Clock Frequency
f
(Note 3)
400
kHz
µs
SCL
f
f
f
f
= 100kHz
= 400kHz
= 100kHz
= 400kHz
4.7
1.6
4.7
0.6
SCL
SCL
SCL
SCL
Bus Free Time Between STOP
and START Condition
t
BUF
START Condition Setup Time
µs
90% of SCL to 90% of SDA,
= 100kHz
0.6
f
SCL
Repeat START Condition Setup
Time
t
µs
µs
µs
SU:STA
HD:STA
SU:STO
90% of SCL to 90% of SDA,
= 400kHz
0.6
0.6
4
f
SCL
START Condition Hold Time
STOP Condition Setup Time
t
t
10% of SDA to 90% of SCL
90% of SCL to 90% of SDA,
f
= 100kHz
SCL
90% of SCL to 90% of SDA,
= 400kHz
0.6
f
SCL
10% to 10%, f
10% to 10%, f
90% to 90%
= 100kHz
= 400kHz
1.3
1.3
0.6
300
SCL
SCL
Clock Low Period
Clock High Period
Data Hold Time
t
µs
µs
ns
LOW
t
HIGH
f
f
f
f
f
f
= 100kHz
SCL
SCL
SCL
SCL
SCL
SCL
t
HD:DAT
= 400kHz (Note 4)
= 100kHz
900
250
100
Data Setup Time
t
ns
µs
SU:DAT
= 400kHz
= 100kHz
1
Receive SCL/DSA Rise Time
t
R
= 400kHz
0.3
300
50
Receive SCL/SDA Fall Time
Pulse Width of Spike Suppressed
SMBus Timeout
t
F
ns
ns
t
0
SP
TIMEOUT
t
SDA low period for interface reset
25
37
45
ms
Note 1: All parameters are tested at T = +25°C. Specifications over temperature are guaranteed by design.
A
Note 2: Timing specifications are guaranteed by design.
Note 3: The serial interface resets when SCL is low for more than t
.
TIMEOUT
Note 4: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL’s falling edge.
_______________________________________________________________________________________
3
7-Channel Precision Temperature Monitor
Typical Operating Characteristics
(V
CC
= 3.3V, T = +25°C, unless otherwise noted.)
A
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
360
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
12
11
10
9
3
2
355
350
345
340
335
330
325
320
1
MAX697
8
7
0
6
-1
-2
-3
-4
5
4
3
2
1
0
3.8
4.8
SUPPLY VOLTAGE (V)
5.3
3.3
4.3
4.8
5.3
3.3
3.8
4.3
0
25
50
75
100
125
SUPPLY VOLTAGE (V)
REMOTE-DIODE TEMPERATURE (°C)
REMOTE-DIODE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
5
4
4
3
100mV
P-P
3
2
2
1
1
0
0
-1
-2
-3
-4
-5
-1
-2
-3
-4
0.1
1
0
25
50
75
100
125
FREQUENCY (MHz)
DIE TEMPERATURE (°C)
LOCAL TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
5
4
3
2
1
0
5
4
100mV
100mV
P-P
P-P
3
2
1
0
-1
-1
-2
-3
-4
-5
-2
-3
-4
-5
0.001
0.01
0.1
1
0.001
0.01
0.1
1
10
FREQUENCY (MHz)
FREQUENCY (MHz)
4
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
Typical Operating Characteristics (continued)
(V
CC
= 3.3V, T = +25°C, unless otherwise noted.)
A
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCE
5
4
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
100mV
P-P
3
2
1
0
-1
-2
-3
-4
-5
0.001
0.01
0.1
1
10
1
10
100
FREQUENCY (MHz)
DXP-DXN CAPACITANCE (nF)
Pin Description
PIN
NAME
FUNCTION
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 floating or connect to V if no
1
DXP1
CC
remote diode is used. Place a 2200pF capacitor between DXP1 and DXN1 for noise filtering.
Cathode Input for Channel 1 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN1.
2
3
4
5
6
7
8
DXN1
DXP2
DXN2
DXP3
DXN3
DXP4
DXN4
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 floating or connect to V
if no
CC
remote diode is used. Place a 2200pF capacitor between DXP2 and DXN2 for noise filtering.
Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diode-
connected transistor to DXN2.
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 floating or connect to V
if no
CC
remote diode is used. Place a 2200pF capacitor between DXP3 and DXN3 for noise filtering.
Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN3.
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 floating or connect to V
if no
CC
remote diode is used. Place a 2200pF capacitor between DXP4 and DXN4 for noise filtering.
Cathode Input for Channel 4 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN4.
_______________________________________________________________________________________
5
7-Channel Precision Temperature Monitor
Pin Description (continued)
PIN
NAME
FUNCTION
Combined Current Source and A/D Positive Input for Channel 5 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave floating or connect to V if no
9
DXP5
CC
remote diode is used. Place a 2200pF capacitor between DXP5 and DXN5 for noise filtering.
Cathode Input for Channel 5 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN5.
10
11
DXN5
DXN6
MAX697
Cathode Input for Channel 6 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN6.
Combined Current Source and A/D Positive Input for Channel 6 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave floating or connect to V
if no
12
DXP6
CC
remote diode is used. Place a 2200pF capacitor between DXP6 and DXN6 for noise filtering.
13, 14
15
NC_
No Connect. Must be connected to ground.
Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of
channels 1, 4, 5, and 6 exceeds the programmed threshold limit.
OVERT
16
V
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
CC
SMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of
any channel exceeds the programmed ALERT threshold.
17
ALERT
18
19
20
SMBDATA SMBus Serial-Data Input/Output. Connect to a pullup resistor.
SMBCLK
GND
SMBus Serial-Clock Input. Connect to a pullup resistor.
Ground
channels. If faster temperature changes must be moni-
Detailed Description
tored in one of the temperature channels, the MAX6697
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 seven channels is consid-
erably greater in this mode than in the default mode.
The MAX6697 is a precision multichannel temperature
monitor that features one local and six remote tempera-
ture-sensing channels with a programmable alert
threshold for each temperature channel and a program-
mable overtemperature threshold for channels 1, 4, 5,
and 6 (see Figure 1). Communication with the MAX6697
is achieved through the SMBus serial interface and a
dedicated alert pin. 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, sys-
tem shutdown, or other thermal-management circuitry.
Low-Power Standby Mode
Standby mode reduces the supply current to less than
15µA by disabling the internal ADC. Enter standby by
setting the STOP bit to 1 in the configuration 1 register.
During standby, data is retained in memory, and the
SMBus interface is active and listening for SMBus com-
mands. The timeout is enabled if a start condition is rec-
ognized 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 conver-
sion cycle is interrupted, and the temperature registers
are not updated. The previous data is not changed and
remains available.
ADC Conversion Sequence
In the default conversion mode, the MAX6697 starts the
conversion sequence by measuring the temperature on
channel 1, followed by 2, 3, local channel, 4, 5, and 6.
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
6
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
V
CC
DXP1
MAX6697
ADC
DXN1
DXP2
10/100μA
OVERT
AVERT
ALARM
ALU
DXN2
DXP3
DXN3
DXP4
COUNT
INPUT
BUFFER
REGISTER BANK
COMMAND BYTE
COUNTER
REMOTE TEMPERATURES
LOCAL TEMPERATURES
ALERT THRESHOLD
DXN4
DXP5
REF
OVERT THRESHOLD
DXN5
DXP6
ALERT RESPONSE ADDRESS
SMBus
INTERFACE
DXN6
SCL
SDA
Figure 1. Internal Block Diagram
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.
SMBus Digital Interface
From a software perspective, the MAX6697 appears as
a series of 8-bit registers that contain temperature mea-
surement 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 remote diode 1 measurement channel provides 11
bits of data (1 LSB = 0.125°C). All other temperature-
measurement 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
The MAX6697 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 regis-
ter was previously selected by a read byte instruction.
Use caution with the shorter protocols in multimaster
_______________________________________________________________________________________
7
7-Channel Precision Temperature Monitor
Write Byte Format
S
ADDRESS
WR
ACK
COMMAND
ACK
DATA
ACK
P
7 bits
8 bits
8 bits
1
Slave Address: equiva-
lent to chip-select line of
a 3-wire interface
Command Byte: selects which
register you are writing to
Data Byte: data goes into the register
set by the command byte (to set
thresholds, configuration masks, and
sampling rate)
MAX697
S
ADDRESS
WR
ACK
COMMAND
ACK
S
ADDRESS
RD
ACK
DATA
///
P
7 bits
8 bits
7 bits
8 bits
Slave Address: equiva-
lent to chip-select line
Command Byte: selects
which register you are
reading from
Slave Address: repeated
due to change in data-
flow direction
Data Byte: reads from
the register set by the
command byte
Send Byte Format
Receive Byte Format
S
ADDRESS
RD
ACK DATA
///
P
S
ADDRESS WR ACK COMMAND ACK
P
7 bits
8 bits
7 bits
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 com-
mand with no data, usually
used for one-shot command
S = Start condition
P = Stop condition
Shaded = Slave transmission
/// = Not acknowledged
Figure 2. SMBus Protocols
Table 1. Main Temperature Register
(High Byte) Data Format
Table 2. Extended Resolution Temperature
Register (Low Byte) Data Format
TEMP (°C)
DIGITAL OUTPUT
TEMP (°C)
DIGITAL OUTPUT
000X XXXX
001X XXXX
010X XXXX
011X XXXX
100X XXXX
101X XXXX
110X XXXX
111X XXXX
>127
0111 1111
0
127
0111 1111
+0.125
+0.250
+0.375
+0.500
+0.625
+0.725
+0.875
126
25
0111 1110
0001 1001
0.00
0000 0000
<0.00
0000 0000
Diode fault (open)
Diode fault (short)
1111 1111
1111 1111 or 1110 1110
conversion results until they have been read. If the
most significant bits have not been read within an
SMBus timeout period (nominally 37ms), normal updat-
ing continues. Table 1 shows the main temperature
register (high byte) data format, and Table 2 shows the
extended resolution register (low byte) data format.
Diode Fault Detection
If a channel’s input DXP_ and DXN_ are left open, the
MAX6697 detects a diode fault. An open diode fault
does not cause either ALERT or OVERT to assert. A bit
in the status register for the corresponding channel is
set to 1 and the temperature data for the channel is
stored as all 1s (FFh). It takes approximately 4ms for
the MAX6697 to detect a diode fault. Once a diode fault
is detected, the MAX6697 goes to the next channel in
8
_______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
A
B
C
D
E
F
G
H
I
J
K
L
M
t
t
HIGH
LOW
SMBCLK
SMBDATA
t
t
BUF
SU:STO
t
t
t
SU:DAT
SU:STA HD:STA
A = START CONDITION
E = SLAVE PULLS SMBDATA LINE LOW
I = MASTER PULLS DATA LINE LOW
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
M = NEW START CONDITION
Figure 3. SMBus Write Timing Diagram
A
B
C
D
E
F
G
H
I
J
K
L
M
t
t
HIGH
LOW
SMBCLK
SMBDATA
t
t
t
t
HD:DAT
HD:STA
SU:STA
SU:DAT
t
t
SU:STO
BUF
A = START CONDITION
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
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
M = NEW START CONDITION
E = SLAVE PULLS SMBDATA LINE LOW
Figure 4. SMBus Read Timing Diagram
the conversion sequence. Depending on operating
conditions, a shorted diode may or may not cause
ALERT or OVERT to assert, so if a channel will not be
used, disconnect its DXP and DXN inputs.
Overtemperature Alarm section). Access to these regis-
ters is provided through the SMBus interface.
ALERT Interrupt Mode
An ALERT interrupt occurs when the internal or external
temperature reading exceeds a high-temperature limit
(user programmable).The ALERT interrupt output signal
can be cleared by reading the status register(s) associ-
ated with the fault(s) or by successfully responding to
an alert response address transmission by the master.
In both cases, the alert is cleared but is reasserted at
the end of the next conversion if the fault condition still
exists. The interrupt does not halt automatic conversions.
The ALERT output is open drain so that multiple devices
Alarm Threshold Registers
There are 11 alarm threshold registers that store over-
temperature ALERT and OVERT threshold values.
Seven of these registers are dedicated to store one
local alert temperature threshold limit and six remote
alert temperature threshold limits (see the ALERT
Interrupt Mode section). The remaining four registers
are dedicated to remote channels 1, 4, 5, and 6 to store
overtemperature threshold limits (see the OVERT
_______________________________________________________________________________________
9
7-Channel Precision Temperature Monitor
Configuration 1 Register
can share a common interrupt line. All ALERT interrupts
can be masked using the configuration 3 register. The
POR state of these registers is shown in Table 1.
The configuration 1 register (Table 4) has several func-
tions. Bit 7(MSB) is used to put the MAX6697 either in
software standby mode (STOP) or continuous conver-
sion mode. Bit 6 resets all registers to their power-on
reset conditions and then clears itself. Bit 5 disables
the SMBus timeout. Bit 4 enables more frequent con-
versions on channel 1, as described in the ADC
Conversion Sequence section. Bit 3 enables resistance
cancellation on channel 1. See the Series Resistance
Cancellation section for more details. The remaining
bits of the configuration 1 register are not used. The
POR state of this register is 0000 0000 (00h).
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 Addresses sec-
tion). Then, any slave device that generated an inter-
rupt attempts to identify itself by putting its own
address on the bus.
MAX697
Configuration 2 Register
The configuration 2 register functions are described in
Table 5. Bits [6:0] are used to mask the ALERT interrupt
output. Bit 6 masks the local alert interrupt and bits 5
through bit 0 mask the remote alert interrupts. The
power-up state of this register is 0000 0000 (00h).
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 arbitra-
tion rules apply, and the device with the lower address
code wins. The losing device does not generate an
acknowledgment and continues to hold the ALERT line
low until cleared. (The conditions for clearing an alert
vary depending on the type of slave device.)
Successful completion of the alert response protocol
clears the output latch. If the condition that caused the
alert still exists, the MAX6697 reasserts the ALERT
interrupt at the end of the next conversion.
Configuration 3 Register
Table 6 describes the configuration 3 register. Bits 5, 4,
3, and 0 mask the OVERT interrupt output for channels
6, 5, 4, and 1. The remaining bits, 7, 6, 2, and 1, are
reserved. The power-up state of this register is 0000
0000 (00h).
OVERT Overtemperature Alarms
The MAX6697 has four overtemperature registers that
store remote alarm threshold data for the OVERT output.
OVERT is asserted when a channel’s measured temper-
ature is greater than the value stored in the correspond-
ing threshold register. OVERT remains asserted until the
temperature drops below the programmed threshold
minus 4°C hysteresis. An overtemperature output can
be used to activate a cooling fan, send a warning, initi-
ate clock throttling, or trigger a system shutdown to pre-
vent component damage. See Table 3 for the POR state
of the overtemperature threshold registers.
Status Registers Functions
Status registers 1, 2, and 3 (Tables 7, 8, and 9) indicate
which (if any) temperature thresholds have been
exceeded and if there is an open-circuit or short-circuit
fault detected with the external sense junctions. Status
register 1 indicates if the measured temperature has
exceeded the threshold limit set in the ALERT registers
for the local or remote-sensing diodes. Status register 2
indicates if the measured temperature has exceeded
the threshold limit set in the OVERT registers. Status
register 3 indicates if there is a diode fault (open or
short) in any of the remote-sensing channels.
Bits in the alert status register clear by a successful
read, but set again after the next conversion unless the
fault is corrected, either by a drop in the measured tem-
perature or an increase in the threshold temperature.
Command Byte Functions
The 8-bit command byte register (Table 3) is the master
index that points to the various other registers within the
MAX6697. This register’s POR state is 0000 0000.
The ALERT interrupt output follows the status flag bit.
Once the ALERT output is asserted, it can be deassert-
ed by either reading status register 1 or by successfully
responding to an alert response address. In both
Configuration Bytes Functions
There are three read-write configuration registers
(Tables 4, 5, and 6) that can be used to control the
MAX6697’s operation.
10 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
Table 3. Command Byte Register Bit Assignment
ADDRESS POR STATE READ/
REGISTER
DESCRIPTION
(HEX)
(HEX)
WRITE
Local
07
01
02
03
04
05
06
41
42
43
44
45
46
17
00
00
00
00
00
00
00
00
00
00
00
00
00
5A
R
R
Read local temperature register
Remote 1
Read channel 1 remote temperature register
Read channel 2 remote temperature register
Read channel 3 remote temperature register
Read channel 4 remote temperature register
Read channel 5 remote temperature register
Read channel 6 remote temperature register
Read/write configuration register 1
Remote 2
R
Remote 3
R
Remote 4
R
Remote 5
R
Remote 6
R
Configuration 1
Configuration 2
Configuration 3
Status1
R/W
R/W
R/W
R
Read/write configuration register 2
Read/write configuration register 3
Read status register 1
Status2
R
Read status register 2
Status3
R
Read status register 3
Local ALERT High Limit
R/W
Read/write local alert high-temperature threshold limit register
Read/write channel 1 remote-diode alert high-temperature
threshold limit register
Remote 1 ALERT High Limit
Remote 2 ALERT High Limit
Remote 3 ALERT High Limit
Remote 4 ALERT High Limit
Remote 5 ALERT High Limit
Remote 6 ALERT High Limit
Remote 1 OVERT High Limit
Remote 4 OVERT High Limit
Remote 5 OVERT High Limit
Remote 6 OVERT High Limit
11
12
13
14
15
16
21
24
25
26
6E
7F
64
64
64
64
6E
7F
5A
5A
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Read/write channel 2 remote-diode alert high-temperature
threshold limit register
Read/write channel 3 remote-diode alert high-temperature
threshold limit register
Read/write channel 4 remote-diode alert high-temperature
threshold limit register
Read/write channel 5 remote-diode alert high-temperature
threshold limit register
Read/write channel 6 remote-diode alert high-temperature
threshold limit register
Read/write channel 1 remote-diode overtemperature threshold
limit register
Read/write channel 4 remote-diode overtemperature threshold
limit register
Read/write channel 5 remote-diode overtemperature threshold
limit register
Read/write channel 6 remote-diode overtemperature threshold
limit register
Remote 1 Extended
Temperature
09
0A
00
R
R
Read channel 1 remote-diode extended temperature register
Read manufacturer ID
Manufacturer ID
4D
______________________________________________________________________________________ 11
7-Channel Precision Temperature Monitor
Table 4. Configuration 1 Register
POR
STATE
BIT
NAME
FUNCTION
Standby Mode Control Bit. If STOP is set to logic 1, the MAX6697 stops
converting and enters standby mode.
7(MSB)
STOP
0
Reset Bit. Set to logic 1 to put the device into its power-on state. This bit is self-
clearing.
6
5
4
POR
0
0
0
MAX697
TIMEOUT
Timeout Enable Bit. Set to logic 0 to enable SMBus timeout.
Channel 1 Fast Conversion Bit. Set to logic 1 to enable fast conversion of
channel 1.
Fast remote 1
Resistance
cancellation
Resistance Cancellation Bit. When set to logic 1, the MAX6697 cancels series
resistance in the channel 1 thermal diode.
3
0
2
1
0
Reserved
Reserved
Reserved
0
0
0
—
—
—
Table 5. Configuration 2 Register
POR
STATE
BIT
NAME
FUNCTION
7(MSB)
Reserved
Mask Local ALERT
Mask ALERT 6
Mask ALERT 5
Mask ALERT 4
Mask ALERT 3
Mask ALERT 2
Mask ALERT 1
0
0
0
0
0
0
0
0
6
5
4
3
2
1
0
Local Alert Mask. Set to logic 1 to mask local channel ALERT.
Channel 6 Alert Mask. Set to logic 1 to mask channel 6 ALERT.
Channel 5 Alert Interrupt Mask. Set to logic 1 to mask channel 5 ALERT.
Channel 4 Alert Mask. Set to logic 1 to mask channel 4 ALERT.
Channel 3 Alert Interrupt Mask. Set to logic 1 to mask channel 3 ALERT.
Channel 2 Alert Mask. Set to logic 1 to mask channel 2 ALERT.
Channel 1 Alert Mask. Set to logic 1 to mask channel 1 ALERT.
cases, the alert is cleared even if the fault condition
exists, but the ALERT output reasserts at the end of the
next conversion. The bits indicating the fault for the
OVERT interrupt output clear only on reading the status
2 register even if the fault conditions still exist. Reading
the status 2 register does not clear the OVERT interrupt
output. To eliminate the fault condition, either the mea-
sured temperature must drop below the temperature
threshold minus the hysteresis value (4°C), or the trip
temperature must be set at least 4°C above the current
temperature.
sensing diodes (see the Typical Application Circuit) or
it can measure the temperature of a discrete diode-
connected transistor.
Effect of Ideality Factor
The accuracy of the remote temperature measurements
depends on the ideality factor (n) of the remote “diode”
(actually a transistor). The MAX6697 is optimized for n
= 1.008. A thermal diode on the substrate of an IC is
normally a pnp with the base and emitter brought out
the collector (diode connection) grounded. DXP_ must
be connected to the anode (emitter) and DXN_ must be
connected to the cathode (base) of this pnp. If a sense
transistor with an ideality factor other than 1.008 is
used, the output data is different from the data obtained
with the optimum ideality factor. Fortunately, the differ-
ence is predictable. Assume a
Applications Information
Remote-Diode Selection
The MAX6697 directly measures the die temperature of
CPUs and other ICs that have on-chip temperature-
12 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
Table 6. Configuration 3 Register
POR
STATE
BIT
NAME
FUNCTION
7(MSB)
6
Reserved
Reserved
0
0
—
—
Channel 6 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 6
OVERT.
5
4
3
Mask OVERT 6
Mask OVERT 5
Mask OVERT 4
0
0
0
Channel 5 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 5
OVERT.
Channel 4 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 4
OVERT.
2
1
Reserved
Reserved
0
0
—
—
Channel 1 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 1
OVERT.
0
Mask OVERT 1
0
remote-diode sensor designed for a nominal ideality
factor n is used to measure the temperature of
increases the conversion time for channel 1 by 125ms.
This feature cancels the bulk resistance of the sensor
and any other resistance in series (wire, contact resis-
tance, etc.). The cancellation range is from 0 to 100Ω.
NOMINAL
a diode with a different ideality factor n1. The measured
temperature T can be corrected using:
M
Discrete Remote Diodes
When the remote-sensing diode is a discrete transistor,
its collector and base must be connected together.
Table 10 lists examples of discrete transistors that are
appropriate for use with the MAX6697. The transistor
must be a small-signal type with a relatively high for-
ward voltage; otherwise, the A/D input voltage range
can be violated. The forward voltage at the highest
expected temperature must be greater than 0.25V at
10µA, and at the lowest expected temperature, the for-
ward voltage must be less than 0.95V at 100µA. Large
power transistors must not be used. Also, ensure that
the base resistance is less than 100Ω. Tight specifica-
tions for forward current gain (50 < ß <150, for exam-
ple) indicate that the manufacturer has good process
⎛
⎞
n
1
T
= T
ACTUAL
M
⎜
⎟
n
⎝
⎠
NOMINAL
where temperature is measured in Kelvin and
for the MAX6697 is 1.008. As an example,
assume you want to use the MAX6697 with a CPU that
has an ideality factor of 1.002. If the diode has no
series resistance, the measured data is related to the
real temperature as follows:
n
NOMIMAL
⎛
⎞
⎟
n
1.008
1.002
⎛
⎞
NOMINAL
T
= T
×
= T
×
= T (1.00599)
M
⎜
⎝
⎟
⎠
ACTUAL
M
M
⎜
n
⎝
⎠
1
For a real temperature of +85°C (358.15K), the mea-
sured temperature is +82.87°C (356.02K), an error of
-2.13°C.
controls and that the devices have consistent V char-
BE
acteristics. Manufacturers of discrete transistors do not
normally specify or guarantee ideality factor. This is
normally not a problem since good-quality discrete
transistors tend to have ideality factors that fall within a
relatively narrow range. We have observed variations in
remote temperature readings of less than 2°C with a
variety of discrete transistors. Still, it is good design
practice to verify good consistency of temperature
readings with several discrete transistors from any
manufacturer under consideration.
Series Resistance Cancellation
Some thermal diodes on high-power ICs can have
excessive series resistance, which can cause tempera-
ture measurement errors with conventional remote tem-
perature sensors. Channel 1 of the MAX6697 has a
series resistance cancellation feature (enabled by bit 3
of the configuration 1 register) that eliminates the effect
of diode series resistance. Set bit 3 to 1 if the series
resistance is large enough to affect the accuracy of
channel 1. The series resistance cancellation function
______________________________________________________________________________________ 13
7-Channel Precision Temperature Monitor
Table 7. Status 1 Register
POR
STATE
BIT
NAME
FUNCTION
7(MSB)
Reserved
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 high-
limit register.
6
5
4
3
2
1
0
Local ALERT
0
0
0
0
0
0
0
MAX697
Channel 6 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 6 remote-diode temperature exceeds the temperature threshold limit
in the remote 6 ALERT high-limit register.
Remote 6 ALERT
Remote 5 ALERT
Remote 4 ALERT
Remote 3 ALERT
Remote 2 ALERT
Remote 1 ALERT
Channel 5 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 5 remote-diode temperature exceeds the programmed temperature
threshold limit in the remote 5 ALERT high-limit register.
Channel 4 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 4 remote-diode temperature exceeds the temperature threshold limit
in the remote 4 ALERT high-limit register.
Channel 3 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 3 remote-diode temperature exceeds the programmed temperature
threshold limit in the remote 3 ALERT high-limit register.
Channel 2 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 2 remote-diode temperature exceeds the temperature threshold limit
in the remote 2 ALERT high-limit register.
Channel 1 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the
channel 1 remote-diode temperature exceeds the temperature threshold limit
in the remote 1 ALERT high-limit register.
ison, making air temperature measurements impracti-
cal. Because the thermal mass of the PCB is far greater
than that of the MAX6697, the device follows tempera-
ture changes on the PCB with little or no perceivable
delay. When measuring the temperature of a CPU or
other IC with an on-chip sense junction, thermal mass
has virtually no effect; the measured temperature of the
junction tracks the actual temperature within a conver-
sion cycle.
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 V . The status register indicates a
CC
diode "fault" for this channel and the channel is ignored
during the temperature-measurement sequence. It is
also good practice to mask any unused channels
immediately upon power-up by setting the appropriate
bits in the Configuration 2 and Configuration 3 regis-
ters. This will prevent unused channels from causing
ALERT# or OVERT# to assert.
When measuring temperature with discrete remote
transistors, the best thermal response times are
obtained with transistors in small packages (i.e., SOT23
or SC70). Take care to account for thermal gradients
between the heat source and the sensor, and ensure
that stray air currents across the sensor package do
not interfere with measurement accuracy. Self-heating
does not significantly affect measurement accuracy.
Remote-sensor self-heating due to the diode current
source is negligible.
Thermal Mass and Self-Heating
When sensing local temperature, the MAX6697 mea-
sures the temperature of the printed-circuit board
(PCB) to which it is soldered. The leads provide a good
thermal path between the PCB traces and the die. As
with all IC temperature sensors, thermal conductivity
between the die and the ambient air is poor by compar-
14 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
Table 8. Status 2 Register
POR
STATE
BIT
NAME
FUNCTION
7(MSB)
6
Reserved
Reserved
0
0
—
—
Channel 6 Remote-Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 6 remote-diode temperature exceeds the temperature
threshold limit in the remote 6 OVERT high-limit register.
5
4
3
Remote 6 OVERT
Remote 5 OVERT
Remote 4 OVERT
0
0
0
Channel 5 Remote Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 5 remote-diode temperature exceeds the temperature
threshold limit in the remote 5 OVERT high-limit register.
Channel 4 Remote Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 4 remote-diode temperature exceeds the temperature
threshold limit in the remote 4 OVERT high-limit register.
2
1
Reserved
Reserved
0
0
—
—
Channel 1 Remote-Diode Overtemperature Status Bit. This bit is set to logic 1
when the channel 1 remote-diode temperature exceeds the temperature
threshold limit in the remote 1 OVERT high-limit register.
0
Remote 1 OVERT
0
Table 9. Status 3 Register
POR
STATE
BIT
7(MSB)
6
NAME
Reserved
FUNCTION
0
—
Channel 6 Remote-Diode Fault Bit. This bit is set to 1 when DXP6 and DXN6
are open circuit or when DXP6 is connected to V
Diode fault 6
0
.
CC
Channel 5 Remote-Diode Fault Bit. This bit is set to 1 when DXP5 and DXN5
are open circuit or when DXP5 is connected to V
5
4
3
2
Diode fault 5
Diode fault 4
Diode fault 3
Diode fault 2
0
0
0
0
.
CC
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 V
.
CC
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 V
.
CC
Channel 2 Remote-Diode Fault Bit. This bit is set to 1 when DXP2 and DXN2
are open circuit or when DXP2 is connected to V
.
CC
Channel 1 Remote-Diode Fault Bit. This bit is set to 1 when DXP1 and DXN1
1
0
Diode fault 1
Reserved
0
0
are open circuit or when DXP1 is connected to V
.
CC
—
______________________________________________________________________________________ 15
7-Channel Precision Temperature Monitor
PCB Layout
Table 10. Remote-Sensors Transistor
Follow these guidelines to reduce the measurement
Manufacturer
error when measuring remote temperature:
MANUFACTURER
MODEL NO.
CMPT3904
1) Place the MAX6697 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. Noise sources include
CRTs, clock generators, memory buses, and PCI
buses.
Central Semiconductor (USA)
Rohm Semiconductor (USA)
Samsung (Korea)
SST3904
KST3904-TF
SMBT3904
Siemens (Germany)
MAX697
Zetex (England)
FMMT3904CT-ND
2) Do not route the DXP-DXN lines next to the deflec-
tion coils of a CRT. Also, do not route the traces
across fast digital signals, which can easily intro-
duce +30°C error, even with good filtering.
Note: Discrete transistors must be diode connected (base
shorted to collector).
Slave Address
Table 11 shows the MAX6697 slave addresses.
3) Route the DXP and DXN traces in parallel and in
close proximity to each other. Each parallel pair of
traces should go to a remote diode. Route these
traces away from any higher voltage traces, such as
+12VDC. Leakage currents from PCB contamination
must be dealt with carefully since a 20MΩ leakage
path from DXP to ground causes about +1°C error.
If high-voltage traces are unavoidable, connect
guard traces to GND on either side of the DXP-DXN
traces (Figure 5).
Table 11. Slave Address
PART
SMBus SLAVE ID
PIN-PACKAGE
20 QSOP
MAX6697EP34
MAX6697EP38
MAX6697EP99
MAX6697EP9C
MAX6697UP34
MAX6697UP38
MAX6697UP99
MAX6697UP9C
0011 010
0011 100
20 QSOP
1001 100
20 QSOP
1001 110
20 QSOP
0011 010
20 TSSOP
20 TSSOP
20 TSSOP
20 TSSOP
4) Route through as few vias and crossunders as pos-
sible to minimize copper/solder thermocouple
effects.
0011 100
1001 100
5) Use wide traces when practical.
1001 110
6) When the power supply is noisy, add a resistor (up
ADC Noise Filtering
to 47Ω) in series with V
.
CC
The integrating ADC has good noise rejection for low-
frequency signals such as power-supply hum. In envi-
ronments with significant high-frequency EMI, connect
an external 2200pF capacitor between DXP_ and
DXN_. Larger capacitor values can be used for added
filtering, but do not exceed 3300pF because it can
introduce errors due to the rise time of the switched
current source. High-frequency noise reduction is
needed for high-accuracy remote measurements.
Noise can be reduced with careful PCB layout as dis-
cussed in the PCB Layout section.
GND
10 mils
10 mils
10 mils
DXP
MINIMUM
10 mils
DXN
GND
Figure 5. Recommended DXP-DXN PCB Traces
16 ______________________________________________________________________________________
7-Channel Precision Temperature Monitor
MAX697
Twisted-Pair and Shielded Cables
Pin Configuration
Use a twisted-pair cable to connect the remote sensor
for remote-sensor distances longer than 8in or in very
TOP VIEW
noisy environments. Twisted-pair cable lengths can be
between 6ft and 12ft before noise introduces excessive
DXP1
DXN1
DXP2
DXN2
DXP3
DXN3
DXP4
DXN4
DXP5
1
2
3
4
5
6
7
8
9
20 GND
errors. For longer distances, the best solution is a
shielded twisted pair like that used for audio micro-
phones. For example, Belden #8451 works well for dis-
tances up to 100ft in a noisy environment. At the
device, connect the twisted pair to DXP and DXN and
the shield to GND. Leave the shield unconnected at the
remote sensor. For very long cable runs, the cable’s
parasitic capacitance often provides noise filtering, so
the 2200pF capacitor can often be removed or reduced
in value. Cable resistance also affects remote-sensor
accuracy. For every 1Ω of series resistance the error is
approximately +1/2°C.
19 SMBCLK
18 SMBDATA
17 ALERT
MAX6697
16
15 OVERT
14
V
CC
NC1
13 NC2
12 DXP6
11 DXN6
DXN5 10
QSOP/TSSOP
Chip Information
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in
the package code indicates RoHS status only. Package draw-
ings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
PROCESS: BiCMOS
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
20 QSOP
E20-1
21-0055
21-0066
20 TSSOP
U20-2
______________________________________________________________________________________ 17
7-Channel Precision Temperature Monitor
MAX697
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
3
5/09
Corrected remote sensor connections in Typical Application Circuit
1
MAX697
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products Inc.
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