MAXIM MAX6683AUB

19-2226; Rev 1; 7/04
KIT
ATION
EVALU
E
L
B
AVAILA
Temperature Sensor and
System Monitor in a 10-Pin µMAX
The MAX6683 system supervisor monitors multiple
power-supply voltages, including its own, and also features an on-board temperature sensor. The MAX6683
converts voltages to an 8-bit code and temperatures to
an 11-bit (10-bit-plus-sign) code using an analog-todigital converter (ADC). A multiplexer automatically
sequences through the voltage and temperature measurements. The digitized signals are then stored in registers and compared to the over/underthreshold limits
programmed over the SMBus™/I 2C™-compatible 2wire serial interface.
When a temperature measurement exceeds the programmed threshold, or when an input voltage falls outside the programmed voltage limits, the MAX6683
generates a latched interrupt output ALERT. Three
interrupt modes are available for temperature excursions. These are default mode, one-time interrupt
mode, and comparator mode. The ALERT output is
cleared, except for temperature interrupts generated in
comparator mode, by reading the Interrupt Status register (Table 5). The ALERT output can also be masked
by writing to the appropriate bits in the Interrupt Mask
register (Table 6) or by setting bit 1 of the Configuration
register (Table 4) to zero. The MAX6683 SMBus/I2Ccompatible interface also responds to the SMB alert
response address.
Applications
Features
♦ Monitors Local Temperature
♦ Monitors Three External Voltages (1.8V, 2.5V, 5V
Nominal)
♦ Monitors VCC (3.3V Nominal)
♦ User-Programmable Voltage and Temperature
Thresholds
♦ Alert Function with Ability to Respond to SMB
Alert Response Address
♦ +2.7V to +5.5V Supply Range
♦ -40°C to +125°C Temperature Range
♦ 60Hz or 50Hz Line-Frequency Rejection
♦ Tiny 10-Pin µMAX Package
♦ MAX6683EVKIT Available
Ordering Information
PART
TEMP RANGE
MAX6683AUB
PIN-PACKAGE
-40°C to +125°C
10 µMAX
Workstations
Servers
Networking
Telecommunications
Typical Application Circuit
1.8V
Pin Configuration
TOP VIEW
VCC = +3.3V
CPU
1.8VIN 1
0.1μF
2.5VIN
10kΩ
TO 1.8V
TO 2.5V
TO 5V
1.8VIN
2.5VIN
5VIN
VCC
SCL
SDA
N.C.
ADD
GND
ALERT
I2C/SMBus
CONTROLLER
10 VCC
2
MAX6683
9
SCL
5VIN
3
8
SDA
N.C.
4
7
ADD
GND
5
6
ALERT
SMBus is a trademark of Intel Corp.
I2C is a trademark of Philips Corp.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX6683
General Description
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND
All Pins...................................................................-0.3V to +6.0V
SDA, ALERT Current ...........................................-1mA to +50mA
Continuous Power Dissipation (TA = +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
Junction Temperature ......................................................+150°C
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
(TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
200
500
POWER SUPPLY
Supply Voltage
Supply Current
VCC
2.7
ICC
Operating
ISD
Shutdown mode, interface inactive
Power-On Reset (POR) Voltage
10
VCC, rising or falling edge
2
µA
V
TEMPERATURE
TA = +25°C, VCC = +3.3V
Accuracy
Resolution
Supply Sensitivity
±3
0°C ≤ TA ≤ +125°C, VCC = +3.3V
±4
-40°C ≤ TA ≤ +125°C, VCC = +3.3V
±6
Read word mode
0.125
PSS
0.7
°C
°C
±1.5
°C/V
±1.5
%
ADC CHARACTERISTICS
Total Unadjusted Error
TUE
VIN > 10LSBs
Differential Nonlinearity
DNL
VIN > 10LSBs
Supply Sensitivity
PSS
Input Resistance
RIN
Total Monitoring Cycle Time
tc
±1
±1
1.8VIN, 2.5VIN, 5VIN
100
(Note 1)
LSB
LSB/V
150
200
kΩ
200
300
ms
0.8
V
SCL, SDA, ADD
Logic Input Low Voltage
VIL
Logic Input High Voltage
VIH
Input Leakage Current
Output Low Voltage
VCC ≤ 3.6V
2.0
VCC > 3.6V
2.6
V
ILEAK
VIN = 0 or 5V
±1
µA
VOL
ISINK = 3mA
400
mV
ISINK = 1.2mA, VCC > 2.7V
0.3
ISINK = 3.2mA, VCC > 4.5V
0.4
ALERT
Output Low Voltage
2
VOLA
_______________________________________________________________________________________
V
Temperature Sensor and
System Monitor in a 10-Pin µMAX
(TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
400
kHz
TIMING (Figures 3 and 4)
Serial Clock Frequency
fSCL
0
Bus Free Time Between Stop
and Start
TBUF
1.3
µs
Start Condition Hold Time
tHD:STA
0.6
µs
Stop Condition Hold Time
tSU:STO
0.6
µs
Clock Low Time
TLOW
1.3
µs
Clock High Time
THIGH
0.6
µs
Data Setup Time
tSU:DAT
100
ns
Data Hold Time
tHD:DAT
(Note 2)
0
0.9
µs
(Note 3)
20 +
0.1Cb
ns
tR
(Note 3)
300
ns
Receive SCL/SDA Minimum Fall
Time
tF
(Note 3)
20 +
0.1Cb
ns
Receive SCL/SDA Maximum Fall
Time
tF
(Note 3)
300
ns
Transmit SDA Fall Time
tF
Cb = 400pF, ISINK = 3mA
Pulse Width of Spike
Suppressed
tSP
(Note 4)
Receive SCL/SDA Minimum
Rise Time
tR
Receive SCL/SDA Maximum
Rise Time
20 +
0.1Cb
300
50
ns
ns
Note 1: Total monitoring time includes temperature conversion and four analog input voltage conversions.
Note 2: A master device must provide at least a 300ns hold time for the SDA signal, referred to VIL of the SCL signal, to bridge the
undefined region of SCL’s falling edge.
Note 3: Cb = total capacitance of one bus line in pF. Rise and fall times are measured between 0.3 ✕ VCC to 0.7 ✕ VCC.
Note 4: Input filters on SDA, SCL, and ADD suppress noise spikes <50ns.
_______________________________________________________________________________________
3
MAX6683
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = +3.3V, ADD = GND, TA = +25°C, unless otherwise noted.)
C
200
D
E
150
A: TA = +125°C
B: TA = +85°C
C: TA = +25°C
D: TA = 0°C
E: TA = -40°C
100
50
0
2.5
3.0
3.5
400
375
350
325
300
3
275
4.5
5.0
100
10
-2
TA = -40°C
3.0
4
3
2
1
MAX6683 toc05
5
MAX6683 toc04
VCC = +5V
BYPASS CAP REMOVED
200mVp-p
3.5
4
3
2
1
0
-1
-2
-3
-4
0
-5
1
10
100
1k
SUPPLY NOISE FREQUENCY (Hz)
4
10k
-50
-25
4.0
4.5
SUPPLY VOLTAGE (V)
TEMPERATURE ERROR
vs. TEMPERATURE
TEMPERATURE ERROR (°C)
TEMPERATURE ERROR (°C)
-1
2.5
1000
TEMPERATURE ERROR
vs. SUPPLY NOISE FREQUENCY
5
TA = 0°C
0
CLOCK FREQUENCY (kHz)
SUPPLY VOLTAGE (V)
6
TA = +85°C
1
-4
1
5.5
2
-3
250
4.0
MAX6683 toc03
425
SUPPLY CURRENT (μA)
A
B
VCC = +5V
SCL = 3Vp-p
TEMPERATURE ERROR (°C)
300
4
MAX6683 toc02
INTERFACE INACTIVE
250
450
MAX6683 toc01
350
TEMPERATURE ERROR
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. SCL CLOCK FREQUENCY
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT (μA)
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
0
25
50
75
100
125
TEMPERATURE (°C)
_______________________________________________________________________________________
5.0
5.5
Temperature Sensor and
System Monitor in a 10-Pin µMAX
PIN
NAME
FUNCTION
1
1.8VIN
Analog Input. Monitors 1.8V nominal supply.
2
2.5VIN
Analog Input. Monitors 2.5V nominal supply.
3
5VIN
Analog Input. Monitors 5V nominal supply.
4
N.C.
No Connect. Not internally connected. Connect to GND to improve thermal conductivity.
5
GND
Ground
6
ALERT
7
ADD
SMBus/I2C-Compatible Address Select Input. ADD is sampled at the beginning of each SMBus/I2C
transaction, and the 2LSBs of the Slave Address register are detemined by ADD’s connection to GND, SDA,
SCL, or VCC.
8
SDA
SMBus/I2C-Compatible Serial Data Interface
9
SCL
SMBus/I2C-Compatible Clock Input
10
VCC
Supply Voltage Input, +2.7V to +5.5V. Also serves as a voltage monitor input. Bypass VCC to GND with a
0.1µF capacitor.
SMBus Alert (Interrupt) Output, Open Drain. Alerts the master that a temperature or voltage limit has been
violated.
Detailed Description
The MAX6683 is a voltage and temperature monitor
designed to communicate through an SMBus/I2C interface with an external microcontroller (µC). A µC with no
built-in I2C or SMBus capabilities can generate SMBus
serial commands by “bit-banging” general-purpose
input-output (GPIO) pins.
The MAX6683 can monitor external supply voltages of
typically 1.8V, 2.5V, 5V, as well as its own supply voltage and temperature. This makes it ideal for supervisor
and thermal management applications in telecommunications, desktop and notebook computers, workstations, and networking equipment. Voltage inputs are
converted to an 8-bit code and temperature is converted to an 11-bit code. The high-order 8 bits of the temperature conversion can be read using a read byte
operation through the I2C interface. The full 11-bit temperature conversion is read using a read word operation and disregarding the lower 5 bits of the low byte.
By setting bit 5 of the Configuration Register to 1, the
temperature conversion can be reduced to 9 bits with a
four-fold reduction in conversion time. In this case, the
lower 7 bits of the low byte should be disregarded; 8bit temperature data has a resolution of 1°C/LSB, while
11-bit temperature data has a resolution of 0.125°C/
LSB. Setting bit 5 of the Configuration Register to 1
reduces the monitoring cycle time by a factor of 4. In
this case, a read word operation for temperature data
yields a 9-bit code in which the lower 7 bits of the low
byte should be disregarded. The LSB of the 9-bit temperature data has a value of 0.5°C.
Each input voltage is scaled down by an on-chip resistive voltage-divider so that its output, at the nominal
input voltage, is 3/4 of the ADC’s full-scale range, or a
decimal count of 192 (Table 3). Input voltages other
than the nominal values may be used; ensure that they
fall within the usable ranges of pins to which they are
applied. Attenuate voltages greater than 6V with an
external resistive voltage-divider.
Writing a 1 to bit 0 of the Configuration Register starts
the monitoring function. The device performs a sequential sampling of all the inputs, starting with the internal
temperature sensor and continuing with 2.5VIN, 1.8VIN,
5VIN, and VCC. If the master terminates the conversion,
the sequential sampling does not stop until the sampling cycle is completed and the results are stored.
When it starts again, it always starts with the temperature measurement.
An interrupt signal is generated when a temperature
measurement goes above the hot limit or when a voltage measurement is either above the high limit or
below the low limit. This causes the open-drain output
ALERT to go to the active-low state and set each corresponding interrupt status bit (bits 0 through 4) to 1
(Table 5). The interrupt is cleared by reading the
Interrupt Status Register except for temperature interrupts generated in comparator mode. Reading the
Interrupt Status Register also clears the register itself,
except for temperature interrupt bits set in comparator
mode.
_______________________________________________________________________________________
5
MAX6683
Pin Description
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
Table 1. Register Map
ADDRESS
READ/WRITE
POWER-ON DEFAULT
20h
R
—
21h
R
—
Data register for 1.8VIN measurement
22h
R
—
Data register for 5VIN measurement
23h
R
—
Data register for VCC measurement
Data register for temperature measurement
27h
R
—
2Bh
R/W
1101 0011 (1.1 × 2.5V)
High limit for 2.5VIN
2Ch
R/W
1010 1101 (0.9 × 2.5V)
Low limit for 2.5VIN
2Dh
R/W
1101 0011 (1.1 × 1.8V)
High limit for 1.8VIN
2Eh
R/W
1010 1101 (0.9 × 1.8V)
Low limit for 1.8VIN
2Fh
R/W
1101 0011 (1.1 × 5V)
High limit for 5VIN
30h
R/W
1010 1101 (0.9 × 5V)
Low limit for 5VIN
31h
R/W
1101 0011 (1.1 × 3.3V)
High limit for VCC
32h
R/W
1010 1101 (0.9 × 3.3V)
Low limit for VCC
39h
R/W
0101 0000 (+80°C)
Hot temperature limit
3Ah
R/W
0100 0001 (+65°C)
Hot temperature hysteresis
40h
R/W
0000 1000
Configuration Register
41h
R
0000 0000
Interrupt Status Register
43h
R/W
0000 0000
Interrupt Mask Register
48h
R/W
0010 1XXY
Device Address Register. The values of XX are
dependent on the status of the ADD pin.
Power-On Default ADD Connection
0010 100Y
To GND
0010 101Y
To VCC
0010 110Y
To SDA
0010 111Y
To SCL
Y (bit 0) is the SMBus read/write bit. When the 7-bit chip
address is read back from the Serial Address Register,
an 8-bit word is presented with a zero in bit 0 (Y).
4Bh
R/W
0000 0000
Temperature Configuration Register
Unless the fault is removed, the ALERT output only
remains cleared until the end of the next conversion
cycle where it is again asserted. The ALERT output can
also be masked by writing to the appropriate bits in the
Interrupt Mask Register (Table 6) or by setting bit 1 of
the Configuration Register (Table 4) to zero.
The 2-wire serial interface accepts both I2C and standard SMBus Write Byte, Read Byte, Read Word, Send
Byte, and Receive Byte commands to program the
alarm thresholds and to read voltage and temperature
data. Voltage data is scaled so that when the nominal
voltage is present at an input (e.g., 1.8V for the 1.8VIN
input), the conversion result is equal to 3/4 of the ADC
full-scale range or a decimal count of 192 (Table 1).
6
DESCRIPTION
Data register for 2.5 VIN measurement
When using the Read Byte command, the temperature
data format is 7 bits plus sign with the LSB equal to
1°C, in two's complement format. When using the Read
Word command, the temperature data format is 10 bits
plus sign, with the LSB equal to 0.125°C, in two’s complement format. See Table 2 for the temperature data
format.
The MAX6683 has only one address input, ADD.
Connect ADD to GND, VCC , SDA, or SCL to select one
of four different address codes. Whenever an
SMBus/I 2C transaction is initiated, the 2LSBs of the
Slave Address Register are determined by connection,
setting the chip address to one of four possible values.
In addition, an address code can also be directly writ-
_______________________________________________________________________________________
Temperature Sensor and
System Monitor in a 10-Pin µMAX
HIGH BYTE
TEMPERATURE
(°C)
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(HEX)
+125
0111 1101
7D
+25
0001 1001
19
Low-Power Shutdown Mode
+1
0000 0001
01
Setting bit 0 in the Configuration Register to zero stops
the monitoring loop and puts the MAX6683 into lowpower shutdown mode. In this mode, the SMBus/I2C
interface remains active, and the supply current drops
to 10µA or less.
0
0000 0000
00
-1
1111 1111
FF
-25
1110 0111
E7
-40
1101 1000
D8
Power-On Reset
LOW BYTE
0.875
1110 0000
D0
0.125
0010 0000
20
The MAX6683 POR supply voltage is typically 2V.
Below this supply voltage, all registers are reset, the
device is put into shutdown mode, and the SMBus/I2C
interface is inactive.
Alarm Threshold Registers
ten to the Serial Address Register. This code overwrites
the code set by connection of the ADD pin, until the
MAX6683 is taken through a POR cycle.
Two registers, a hot temperature limit (THOT) at 39h and
a hot temperature hysteresis (T HYST ) at 3Ah, store
alarm threshold data (Table 1). If a measured temperature exceeds the value of THOT, an ALERT is asserted.
Alerts are cleared and reasserted depending on
the interrupt mode selected in the Temperature
Configuration Register (see ALERT Interrupts).
ADC and Multiplexer
The ADC integrates over a 66ms period, an integral
multiple of the line period with excellent noise rejection.
The internal oscillator is trimmed to produce a 66ms
conversion time for temperature and 33ms for each
Table 3. Voltage Data Format
ADC OUTPUT
CODE
INPUT VOLTAGE
AT 1.8VIN
INPUT VOLTAGE
AT 2.5VIN
INPUT VOLTAGE
AT 5VIN
VCC = +3.3V
LSB weight
9.375mV (1.8V/192)
13mV (2.5V/192)
26mV (5V/192)
17.2mV (3.3V/192)
0
< 9.375mV
< 13mV
< 26mV
—
1
9.375mV to 18.75mV
13mV to 26mV
26mV to 52mV
—
2
18.75mV to 28.125mV
26mV to 39mV
52mV to 78mV
—
—
—
—
—
—
64 (1/4 scale)
600mV to 609.4mV
833mV to 846mV
1.664V to 1.692V
—
—
—
—
—
—
128 (1/2 scale)
1.2V to 1.2094V
1.667V to 1.680V
3.330V to 3.560V
—
—
—
—
—
—
192 (3/4 scale)
1.8V to 1.737V
2.5V to 2.513V
5V to 5.026V
3.3V to 3.317V
—
—
—
—
—
253
2.372V to 2.381V
3.294V to 3.307V
6.566V to 6.640V
4.348V to 4.366V
254
2.381V to 2.391V
3.572V to 3.586V
6.615V to 6.640V
4.366V to 4.383V
255
= 2.391V
= 3.586V
= 6.640V
= 4.383V
_______________________________________________________________________________________
7
MAX6683
voltage. This is equivalent to 4 and 2 cycles of 60Hz,
respectively, and provides protection against noise
pickup from the main supply. The internal oscillator frequency can be changed to provide the same protection
against 50Hz by setting bit 7 in the Configuration
Register to 1 (Table 4). The multiplexer automatically
sequences through the inputs, measuring voltages and
temperature.
Table 2. Temperature Data Format
(Two's Complement)
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
Table 4. Configuration Register (Address 40h, Power-On Default = 08h)
BIT
NAME
READ/WRITE
DESCRIPTION
0
Start/Stop
R/W
This bit controls the monitoring loop. Setting the bit to zero stops the
monitoring loop and puts the device into shutdown mode. The I2C/SMBus
interface is still active during the shutdown mode. Setting the bit to 1 starts the
monitoring cycle. All high/low limits should be set before setting this bit to 1.
1
ALERT Enable
R/W
This bit is used to enable or disable the ALERT output. Setting the bit to 1
enables the ALERT output; setting the bit to 0 disables the ALERT output.
2
Reserved
—
—
3
ALERT Clear
R/W
This bit is used to clear the ALERT output when it is set to high. It does not
affect the Interrupt Status Register. The monitoring loop does not start until the
bit is set to zero.
4
Line Frequency
Select
R/W
This bit controls the internal clock frequency. Setting the bit to 1 changes the
clock frequency to 51.2kHz from 61.4kHz. This can improve the measurement
accuracy when the power-line frequency is at 50Hz.
5
Short Cycle
R/W
This bit reduces the conversion time by a factor of 4 when it is set to 1.
6
Reserved
—
7
Reset
R/W
—
This bit is used as a reset signal for the register initialization. The 1 of this bit
resets all the register values into the power-up default mode, including bit 7
itself.
Table 5. Interrupt Status Register (Address 41h, Power-Up Default = 00h)
BIT
NAME
READ/WRITE
DESCRIPTION
0
2.5VIN-Error
R
A 1 indicates either a high or low limit has been exceeded at the 2.5VIN input.
1
1.8VIN-Error
R
A 1 indicates either a high or low limit has been exceeded at the 1.8VIN input.
2
5VIN-Error
R
A 1 indicates either a high or low limit has been exceeded at the 5VIN input.
3
VCC-Error
R
A 1 indicates either a high or low limit has been exceeded at the VCC input.
4
Temp-Error
R
A 1 indicates either a high or low limit has been exceeded at the internal
temperature sensor. The conditions that generate and clear this bit depend
on the temperature interrupt mode selected by bits 0 and 1 in the
Temperature Configuration Register.
5, 6, 7
Reserved
—
—
The POR state of the THOT register is 0101 0000 or
+80°C. The POR state of the THYST register is 0100
0001 or +65°C.
High and low limits for the voltage inputs are stored in
registers 2Bh through 32h. If a measured voltage is less
than VLOW or greater than VHIGH, an ALERT is asserted.
The POR states of the high and low voltage limits are
1.1 and 0.9 times the nominal voltage for each input.
8
Interrupt Status Byte Functions
The Interrupt Status Register records temperature or
voltage fault conditions whenever a limit is exceeded
(Table 5). Bits 0 through 3 correspond to the 2.5V, 1.8V,
5V, and VCC voltage inputs and bit 4 corresponds to
the temperature. If a threshold has been crossed, the
appropriate bit contains a 1. In the default and one-time
interrupt modes, reading the status register clears the
register until a new out-of-range condition is detected.
_______________________________________________________________________________________
Temperature Sensor and
System Monitor in a 10-Pin µMAX
MAX6683
Table 6. Interrupt Mask Register (Address 43h, Power-Up Default = 00h)
BIT
NAME
READ/WRITE
DESCRIPTION
0
2.5V
R/W
Setting the bit to 1 disables the Interrupt Status Register bit (bit 0) and the
ALERT output for the 2.5VIN input.
1
1.8V
R/W
Setting the bit to 1 disables the Interrupt Status Register bit (bit 1) and the
ALERT output for the 1.8VIN input.
2
5V
R/W
Setting the bit to 1 disables the Interrupt Status Register bit (bit 2) and the
ALERT output for the 5VIN input.
3
3.3V
R/W
Setting the bit to 1 disables the Interrupt Status Register bit (bit 3) and the
ALERT output for the VCC input.
4
Temp.
R/W
Setting the bit to 1 disables the Interrupt Status Register bit (bit 4) and the
ALERT output for temperature.
5, 6, 7
Reserved
—
—
Table 7. Temperature Configuration Register (Address 4Bh, Power-Up Default = 00h)
BIT
0, 1
2−7
NAME
Hot Temperature
Interrupt Select
Reserved
READ/WRITE
R/W
DESCRIPTION
Bit 1, bit 0 = 00: Default mode
Bit 1, bit 0 = 01: One-time interrupt mode
Bit 1, bit 0 = 10: Comparator mode
Bit 1, bit 0 = 11: Default mode
—
ALERT Interrupts
An out-of-range voltage or temperature causes the
ALERT output signal to be asserted. However, if the
assertion is caused by an out-of-range temperature, the
ALERT output can operate in one of three different
modes: default, one-time interrupt, or comparator
mode. In the default and one-time interrupt modes, the
ALERT signal and Interrupt Status Register are cleared
by reading the Interrupt Status Register (Table 5). In
comparator mode, ALERT is only cleared when the fault
condition is removed. Reading the Interrupt Status
Register clears all but bit 4 of the Status Register if the
fault condition is not removed. Reading the Interrupt
Status Register with the fault condition removed clears
the entire register. Unless the fault is removed, ALERT
is reasserted after the next conversion cycle. The
ALERT output can also be masked by writing to the
appropriate bits in the Interrupt Mask Register (Table 6)
or by setting bit 1 of the Configuration Register (Table
4) to zero.
The interrupt does not halt conversions. New temperature and voltage data continue to be available over the
SMBus interface after ALERT is asserted. The three
temperature ALERT modes are shown in Figure 1 and
—
are selected through the Temperature Configuration
Register (Table 7). The ALERT output pin is open drain,
so the device can share a common interrupt line.
Default Mode
An interrupt is initiated when temperature exceeds
THOT (address 39h). The interrupt is cleared only by
reading the Interrupt Status Register. An interrupt continues to be generated on subsequent measurements
until the temperature goes below THYST (address 3Ah).
One-Time Interrupt Mode
An interrupt is initiated when temperature exceeds
THOT (address 39h). The interrupt is cleared only by
reading the Interrupt Status Register. The next interrupt
is then initiated when temperature falls below the THYST
(address 3Ah).
Comparator Mode
An interrupt is initiated when temperature exceeds
THOT (address 39h). The ALERT output remains asserted low until the temperature goes below THOT. Reading
the Interrupt Status Register does not clear the ALERT
output or interrupt status bit in the register. The interrupt continues to be generated on subsequent measurements until the temperature falls below THOT.
_______________________________________________________________________________________
9
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
TEMPERATURE
MONITORING CYCLE
INTERRUPT
STATUS READ
THOT
THYST
ALERT
DEFAULT MODE
ALERT
ONE-TIME
INTERRUPT MODE
ALERT
COMPARATOR MODE
Figure 1. Alert Response to Temperature Interrupts
Write Byte Format
S
ADDRESS
W/R
7 bits
0
ACK
COMMAND
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
ADDRESS
W/R
7 bits
0
ACK
COMMAND
ACK
S
8 bits
Slave Address: equivalent to chip-select line of
a 3-wire interface
Command Byte: selects
which register you are
reading from
Send Byte Format
S
ADDRESS
W/R
7 bits
1
ACK
Slave Address: repeated
due to change in dataflow direction
W/R
7 bits
0
ACK
COMMAND
ACK
P
S
ADDRESS
8 bits
7 bits
W/R
Data Byte: reads from
the register set by the
command byte
ADDRESS
W/R
7 bits
0
ACK
COMMAND
ACK
8 bits
S
ACK
DATA
A
P
8 bits
1
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
Read Word Format
ADDRESS
7 bits
W/R ACK
1
DATA_LOW_byte
8 bits
ACK
DATA_HIGH_byte
8 bits
Shaded = Slave transmission
A = Not acknowledged
Figure 2. SMBus Protocols
10
P
Receive Byte Format
ADDRESS
S = Start condition
P = Stop condition
A
8 bits
Data Byte: writes data to the
register commanded by the
last Read Byte or Write Byte
transmission
S
DATA
______________________________________________________________________________________
A
P
Temperature Sensor and
System Monitor in a 10-Pin µMAX
tLOW
B
tHIGH
C
D
E
F
G
H
I
J
K
L
MAX6683
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 MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
I = SLAVE PULLS SMBDATA LINE LOW
Figure 3. SMBus Write Timing Diagram
A
tLOW
B
tHIGH
C
D
E
F
G
H
I
J
K
L
M
SMBCLK
SMBDATA
tSU:STA
tHD:STA
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
tSU:DAT
tSU:STO tBUF
E = SLAVE PULLS SMBDATA LINE LOW
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
M = NEW START CONDITION
Figure 4. SMBus Read Timing Diagram
SMBus/I2C-Compatible Digital Interface
From a software prospective, the MAX6683 appears as
a set of byte-wide registers that contain voltage and temperature data, alarm threshold values, or control bits.
The device employs five standard SMBus protocols:
write byte, read byte, read word, send byte, and
receive byte (Figures 2, 3, 4).
Slave Address
The device address can be set to one of four different
values by pin strapping ADD to GND, SDA, SCL, or
VCC, so more than one MAX6683 can reside on the
same bus without address conflicts (Table 1). The
address pin state is checked at the beginning of each
SMBus/I2C transaction and is insensitive to glitches on
V CC . Any address code can also be written to the
Serial Address Register and overwrites the code set by
connecting the ADD pin until the MAX6683 is taken
through a POR cycle.
The MAX6683 also responds to the SMBus alert
response address (see Alert Response Address).
______________________________________________________________________________________
11
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
UPPER BYTE
D10
D9
D8
D7
D6
LOWER BYTE
D5
D4
D3
D2
D1
D0
X
X
X
X
X
X
X
X
11-BIT READ FORMAT
UPPER BYTE
D8
D7
D6
D5
D4
LOWER BYTE
D3
D2
D1
D0
X
X
X
9-BIT READ FORMAT
X
X = DON'T CARE
Figure 5. Read Temperature Format
Alert Response Address
The SMBus alert response interrupt pointer provides
quick fault identification for simple slave devices that
lack the complex, expensive logic needed to be a bus
master. Usually the ALERT outputs of several slave
devices are wire-ORed to the same interrupt input of
the host master. Upon receiving an interrupt signal, the
host master can broadcast a receive byte transmission
(Figure 2) with the alert response address (0001 100).
A read operation is denoted by a 1 in the eighth
address bit. Then, any slave device that generated an
interrupt attempts to identify itself by putting its own
address on the bus.
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 arbitration rules apply, and the device with the lower address
code wins. The losing device does not generate an
acknowledge signal and continues to hold the interrupt
line low until serviced. The MAX6683 does not automatically clear its ALERT when it responds to an alert
response address. The host master must then clear or
mask the ALERT by reading the Interrupt Status
Register, writing to the Interrupt Mask Register, or setting bit 1 of the Configuration Register to zero before it
can identify other slaves generating an interrupt.
Command Byte Functions
The 8-bit Command Byte Register (Table 1) is the master index that points to the other data, configuration,
limits, and address registers within the MAX6683. The
functions of those other registers are described below.
Configuration Byte Functions
The Configuration Register (Table 4) is a read-write register with several functions:
12
•
Bit 0 puts the MAX6683 into software standby mode
(STOP) or autoconvert (START) mode. The 2-wire
interface is still active in the standby mode. All voltage and temperature limits should be set before
setting this bit to 1.
•
Bit 1 enables and disables the ALERT output.
Setting this bit to 1 enables the ALERT output.
•
Bit 2 is reserved.
•
Bit 3 clears the ALERT output and stops the monitoring loop when set to 1. Clearing the output does
not affect the contents of the Interrupt Status
Registers.
•
Bit 4 sets the analog-to-digital conversion speed to
minimize interference from power-line frequencies.
Setting this bit to 1 can improve accuracy when the
power-line frequency is 50Hz. When the power-line
frequency is 60Hz, bit 4 should be zero.
•
Bit 5 reduces the oversampling ratio in the ADC
from 8 to 2. This reduces the monitoring cycle time
by a factor of 4 to typically 50ms at the cost of
reduced noise rejection.
•
Bit 6 is reserved.
•
Bit 7 resets all register values to their power-up
default values. To reset all registers, set bit 7 to 1.
This also resets bit 7 to its power-up value of zero.
Read Temperature
The MAX6683 reads out temperature in an 8-, 9-, or 11-bit
two's complement format. To obtain the 8-bit temperature
data (7 bits plus sign), execute a Read Byte command to
the Temperature Data Register (address 27h).
To obtain the 11-bit temperature data (10 bits plus
sign), execute a Read Word command to the
Temperature Data Register (address 27h). When per-
______________________________________________________________________________________
Temperature Sensor and
System Monitor in a 10-Pin µMAX
Sensing Circuit Board and
Component Temperatures
VCC
1.8VIN
2.5VIN
5.0VIN
Applications Information
INPUT VOLTAGE
SCALING AND
MULTIPLEXER
ADC
DATA AND
CONTROL
LOGIC
TEMPERATURE
SENSOR
VOLTAGE
REFERENCE
I2C/SMBusCOMPATIBLE
INTERFACE
SDA
SCL
ALERT
ADD
forming a Read Word operation, the MAX6683 writes
the 11 bits of data to the bus in two 8-bit words. The
upper byte contains the MSBs, while the lower byte
contains the 3LSBs (Figure 5). D9–D3 of the upper byte
represent the whole decimal number of the temperature
conversion and D10 is sign. D2–D0 of the lower byte
represent 1/2, 1/4, 1/8 of a degree, respectively, and
the remaining bits are disregarded.
Nine-bit temperature data (8 bits plus sign) is obtained
by setting bit 5 of the Configuration Register (address
40h) to 1, reducing the conversion time by a factor of
four, and executing a Read Word command to the
Temperature Data Register (address 27h). The upper
byte contains the MSBs, while the lower byte contains
the LSB (Figure 5). D7–D1 of the upper byte represent
the whole decimal number of the temperature conversion and D0 is sign. D0 of the lower byte represents 1/2
of a degree, and the remaining bits are disregarded.
Temperature sensor ICs like the MAX6683 that sense
their own die temperatures must be mounted on or
close to the object whose temperature they are intended to measure. Because there is a good thermal path
between the 10-pin µMAX package’s metal leads and
the IC die, the MAX6683 can accurately measure the
temperature of the circuit board to which it is soldered.
If the sensor is intended to measure the temperature of
a heat-generating component on the circuit board, it
should be mounted as close as possible to that component and should share supply and ground traces (if
they are not noisy) with that component where possible.
This maximizes the heat transfer from the component to
the sensor.
The thermal path between the plastic package and the
die is not as good as the path through the leads, so the
MAX6683, like all temperature sensors in plastic packages, is less sensitive to the temperature of the surrounding air than to the temperature of the leads.
Wiring and circuits must be kept insulated and dry to
avoid leakage and corrosion, especially if they operate
at cold temperatures where condensation can occur.
Chip Information
TRANSISTOR COUNT: 13,446
PROCESS: BiCMOS
______________________________________________________________________________________
13
MAX6683
Functional Diagram
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.)
e
10LUMAX.EPS
MAX6683
Temperature Sensor and
System Monitor in a 10-Pin µMAX
4X S
10
10
INCHES
H
Ø0.50±0.1
0.6±0.1
1
1
0.6±0.1
BOTTOM VIEW
TOP VIEW
D2
MILLIMETERS
MAX
DIM MIN
0.043
A
0.006
A1
0.002
A2
0.030
0.037
0.120
D1
0.116
0.118
0.114
D2
0.116
0.120
E1
0.118
E2
0.114
0.199
H
0.187
L
0.0157 0.0275
L1
0.037 REF
b
0.007
0.0106
e
0.0197 BSC
c
0.0035 0.0078
0.0196 REF
S
α
0°
6°
MAX
MIN
1.10
0.15
0.05
0.75
0.95
3.05
2.95
3.00
2.89
3.05
2.95
2.89
3.00
4.75
5.05
0.40
0.70
0.940 REF
0.177
0.270
0.500 BSC
0.090
0.200
0.498 REF
0°
6°
E2
GAGE PLANE
A2
c
A
b
A1
α
E1
L
D1
L1
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0061
REV.
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. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2004 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.