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PDF MAX1668 Data sheet ( Hoja de datos )
| Número de pieza | MAX1668 | |
| Descripción | Multichannel Remote/Local Temperature Sensors | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-1766; Rev 2; 5/03
Multichannel Remote/Local
Temperature Sensors
________________General Description
The MAX1668/MAX1805/MAX1989 are precise multi-
channel digital thermometers that report the tempera-
ture of all remote sensors and their own packages. The
remote sensors are diode-connected transistors—typi-
cally low-cost, easily mounted 2N3904 NPN types—that
replace conventional thermistors or thermocouples.
Remote accuracy is ±3°C for multiple transistor manu-
facturers, with no calibration needed. The remote chan-
nels can also measure the die temperature of other ICs,
such as microprocessors, that contain an on-chip,
diode-connected transistor.
The 2-wire serial interface accepts standard system
management bus (SMBus™) write byte, read byte, send
byte, and receive byte commands to program the alarm
thresholds and to read temperature data. The data for-
mat is 7 bits plus sign, with each bit corresponding to
1°C, in two’s-complement format.
The MAX1668/MAX1805/MAX1989 are available in
small, 16-pin QSOP surface-mount packages. The
MAX1989 is also available in a 16-pin TSSOP.
________________________Applications
Desktop and Notebook
Computers
Central-Office Telecom
Equipment
LAN Servers
Test and Measurement
Industrial Controls
Multichip Modules
____________________________Features
o Multichannel
4 Remote, 1 Local (MAX1668/MAX1989)
2 Remote, 1 Local (MAX1805)
o No Calibration Required
o SMBus 2-Wire Serial Interface
o Programmable Under/Overtemperature Alarms
o Supports SMBus Alert Response
o Accuracy
±2°C (+60°C to +100°C, Local)
±3°C (-40°C to +125°C, Local)
±3°C (+60°C to +100°C, Remote)
o 3µA (typ) Standby Supply Current
o 700µA (max) Supply Current
o Small, 16-Pin QSOP/TSSOP Packages
_______________Ordering Information
PART
MAX1668MEE
MAX1805MEE
MAX1989MEE
MAX1989MUE
TEMP RANGE
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
PIN-PACKAGE
16 QSOP
16 QSOP
16 QSOP
16 TSSOP
Pin Configuration
TOP VIEW
DXP1 1
DXN1 2
DXP2 3
DXN2 4
(N.C.) DXP3 5
(N.C.) DXN3 6
(N.C.) DXP4 7
(N.C.) DXN4 8
MAX1668
MAX1805
MAX1989
16 GND
15 STBY
14 SMBCLK
13 SMBDATA
12 ALERT
11 ADD0
10 ADD1
9 VCC
( ) ARE FOR MAX1805.
QSOP/TSSOP
Typical Operating Circuit
0.1µF
3V TO 5.5V
200Ω
2200pF
*
2200pF
*
VCC STBY
MAX1668
MAX1805
MAX1989
DXP1
SMBCLK
DXN1
SMBDATA
ALERT
DXP4
DXN4
ADD0 ADD1 GND
10kΩ EACH
CLOCK
DATA
INTERRUPT
TO µC
* DIODE-CONNECTED TRANSISTOR
SMBus is a trademark of Intel Corp.
†Patents Pending
________________________________________________________________ Maxim Integrated Products 1
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 page  
Multichannel Remote/Local
Temperature Sensors
Typical Operating Characteristics (continued)
(Typical Operating Circuit, VCC = +5V, STBY = VCC, configuration byte = X0XXXX00, TA = +25°C, unless otherwise noted.)
TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
2.0
1.8
SQUARE-WAVE AC-COUPLED INTO DXN
2200pF BETWEEN DXN_ AND DXP_
1.6
1.4 100mVP-P
1.2
1.0 50mVP-P
0.8
0.6
0.4
0.2
0
0.1 1 10 100 1000
FREQUENCY (MHz)
TEMPERATURE ERROR
vs. DXP_ TO DXN_ CAPACITANCE
4
2
0
-2
-4
-6
-8
-10
0
10 20 30 40 50
DXP_ TO DXN_ CAPACITANCE (nF)
60
STANDBY SUPPLY CURRENT
vs. CLOCK FREQUENCY
60
STBY = GND
50
40
30 VCC = 5V
20
VCC = 3.3V
10
0
1
10 100
SMBCLK FREQUENCY (kHz)
1000
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
160
STBY = GND
140
ADD0 = ADD1 = GND
120
RESPONSE TO THERMAL SHOCK
125
100
100 75
80
60 50
40
20
0
0
ADD0 = ADD1 = HIGH-Z
1234
SUPPLY VOLTAGE (V)
5
25
16 QSOP IMMERSED IN
+115°C FLUORINERT BATH
0
-2 0 2 4 6 8
TIME (s)
_______________________________________________________________________________________ 5
5 Page 
Multichannel Remote/Local
Temperature Sensors
Table 2. Data Format (Two’s Complement)
TEMP
(°C)
+130.00
+127.00
+126.50
+126.00
+25.25
+0.50
+0.25
+0.00
-0.25
-0.50
-0.75
-1.00
-25.00
-25.50
-54.75
-55.00
-65.00
-70.00
ROUNDED
TEMP
(°C)
+127
+127
+127
+126
+25
+1
+0
+0
+0
+0
-1
-1
-25
-25
-55
-55
-65
-65
DIGITAL OUTPUT DATA BITS
SIGN
MSB
LSB
0 111 1111
0 111 1111
0 111 1111
0 111 1110
0 001 1001
0 000 0000
0 000 0000
0 000 0000
0 000 0000
0 000 0000
1 111 1111
1 111 1111
1 110 0111
1 110 0110
1 100 1001
1 100 1001
1 011 1111
1 011 1111
Diode Fault Alarm
There is a continuity fault detector at DXP_ that detects
whether the remote diode has an open-circuit condi-
tion. At the beginning of each conversion, the diode
fault is checked, and the status byte is updated. This
fault detector is a simple voltage detector; if DXP_ rises
above VCC - 1V (typ) due to the diode current source, a
fault is detected. Note that the diode fault is not
checked until a conversion is initiated, so immediately
after power-on reset, the status byte indicates no fault
is present, even if the diode path is broken.
If any remote channel is shorted (DXP_ to DXN_ or
DXP_ to GND), the ADC reads 0000 0000 so as not to
trip either the THIGH or TLOW alarms at their POR set-
tings. In applications that are never subjected to 0°C in
normal operation, a 0000 0000 result can be checked
to indicate a fault condition in which DXP_ is acciden-
tally short circuited. Similarly, if DXP_ is short circuited
to VCC, the ADC reads +127°C for all remote and local
channels, and the device alarms.
ALERT Interrupts
The ALERT interrupt output signal is latched and can
only be cleared by reading the alert response address.
Table 3. Read Format for Alert Response
Address (0001100)
BIT
7
(MSB)
6
5
4
3
2
1
0
(LSB)
NAME
ADD7
ADD6
ADD5
ADD4
ADD3
ADD2
ADD1
1
FUNCTION
Provide the current
MAX1668/MAX1805/MAX1989
slave address that was latched at
POR (Table 8)
Logic 1
Interrupts are generated in response to THIGH and TLOW
comparisons and when a remote diode is disconnected
(for continuity fault detection). The interrupt does not halt
automatic conversions; new temperature data continues
to be available over the SMBus interface after ALERT is
asserted. The interrupt output pin is open drain so that
devices can share a common interrupt line. The interrupt
rate can never exceed the conversion rate.
The interface responds to the SMBus alert response
address, an interrupt pointer return-address feature
(see Alert Response Address section). Prior to taking
corrective action, always check to ensure that an inter-
rupt is valid by reading the current temperature.
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. Upon receiving an ALERT interrupt signal, the
host master can broadcast a receive byte transmission
to the alert response slave address (0001 100). Then
any slave device that generated an interrupt attempts
to identify itself by putting its own address on the bus
(Table 3).
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
acknowledge and continues to hold the ALERT line low
until serviced (implies that the host interrupt input is
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MAX1668.PDF ] | |
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