|
|
PDF MAX6654MEE Data sheet ( Hoja de datos )
| Número de pieza | MAX6654MEE | |
| Descripción | 1C Accurate Remote/Local Temperature Sensor with SMBus Serial Interface | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MAX6654MEE (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
19-1836; Rev 2; 1/02
1°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
General Description
The MAX6654† is a precise digital thermometer that
reports the temperature of both a remote P-N junction
and its own die. The remote junction can be a diode-con-
nected transistor—typically a low-cost, easily mounted
2N3904 NPN type or 2N3906 PNP type—that replaces
conventional thermistors or thermocouples. Remote
accuracy is ±1°C for multiple transistor manufacturers,
with no calibration needed. The remote junction can also
be a common-collector PNP, such as a substrate PNP of
a microprocessor (µP).
The 2-wire serial interface accepts standard System
Management Bus (SMBus)TM, Write Byte, Read Byte,
Send Byte, and Receive Byte commands to program the
alarm thresholds and to read temperature data.
Measurements can be done automatically and
autonomously, with the conversion rate programmed by
the user, or programmed to operate in a single-shot
mode. The adjustable conversion rate allows the user to
optimize supply current and temperature update rate to
match system needs. When the conversion rate is faster
than 1Hz, the conversion results are available as a 7-bit-
plus-sign byte with a 1°C LSB. When the conversion rate
is 1Hz or slower, the MAX6654 enters the extended
mode. In this mode, 3 additional bits of temperature data
are available in the extended resolution register, provid-
ing 10-bit-plus-sign resolution with a 0.125°C LSB.
Single-shot conversions also have 0.125°C per LSB reso-
lution when the conversion rate is 1Hz or slower.
A parasitic resistance cancellation (PRC) mode can also
be invoked for conversion rates of 1Hz or slower by set-
ting bit 4 of the configuration register to 1. In PRC mode,
the effect of series resistance on the leads of the external
diode is canceled. The 11-bit conversion in PRC mode is
performed in <500ms and is disabled for conversion
rates faster than 1Hz. The one-shot conversion is also 11
bits in <500ms.
The MAX6654 default low-temperature measurement
limit is 0°C. This can be extended to -64°C by setting bit
5 of the configuration register to 1.
The MAX6654 is available in a small, 16-pin QSOP sur-
face-mount package.
________________________Applications
Desktop Computers
Notebook Computers
Servers
Thin Clients
Workstations
Test and Measurement
Multichip Modules
SMBus is a trademark of Intel Corp.
I2C is a trademark of Philips Corp.
†Patents pending
Features
o High Accuracy ±1°C (max) from +70°C to +100°C
(Remote)
o 11-Bit, 0.125°C Resolution
o Dual Channel: Measures Remote and Local
Temperature
o No Calibration Required
o Programmable Under/Overtemperature Alarms
o I2C™-Compatible/SMBus Interface
o +3V to +5.5V Supply Range
PART
MAX6654MEE
Ordering Information
TEMP. RANGE
-55°C to +125°C
PIN-PACKAGE
16 QSOP
Typical Operating Circuit
0.1µF
200Ω
+3V TO +5V SUPPLY
CPU VCC STBY
MAX6654
DXP SMBCLK
SMBDATA
DXN
2200pF
ALERT
ADD0 ADD1 GND
10k EACH
CLOCK
DATA
INTERRUPT TO µC
Pin Configuration
TOP VIEW
N.C. 1
VCC 2
DXP 3
DXN 4
N.C. 5
ADD1 6
GND 7
GND 8
MAX6654
16 N.C.
15 STBY
14 SMBCLK
13 N.C.
12 SMBDATA
11 ALERT
10 ADD0
9 N.C.
QSOP
________________________________________________________________ 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  
1°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
Pin Description
PIN
1, 5, 9, 13, 16
2
3
4
6
7, 8
10
11
12
14
15
NAME
N.C.
VCC
DXP
DXN
ADD1
GND
ADD0
ALERT
SMBDATA
SMBCLK
STBY
FUNCTION
No Connection. Not internally connected. May be used for PC board trace routing.
Supply Voltage Input. +3.0V to +5.5V. Bypass to GND with a 0.1µF capacitor. A 200Ω series
resistor is recommended but not required for additional noise filtering.
Combined Current Source and ADC Positive Input for Remote-Junction Channel. If a remote-
sensing junction is not used, connect DXP to DXN.
Combined Current Sink and ADC Negative Input. DXN is internally biased to a diode voltage above
ground.
SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.
Ground
SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.
SMBus Alert (Interrupt) Output. Open drain.
SMBus Serial-Data Input/Output. Open drain.
SMBus Serial-Clock Input
Hardware standby input. Temperature and comparison threshold data are retained in standby
mode. Low = standby mode, high = operating mode.
_______________________________________________________________________________________ 5
5 Page 
1°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
Table 2. Data Format
TEMP (°C)
ROUNDED TEMP (°C)
130.00
127.00
126.00
25.25
0.50
0.00
<0.00 (Note 1)
-1
<-64
Diode fault
(short or open)
+127
+127
+126
+25
+1
0
(Normal mode)
(Extended temp mode)
(Extended temp mode)
DIGITAL
OUTPUT
0 111 1111
0 111 1111
0 111 1110
0 001 1001
0 000 0001
0 000 0000
1 000 0000
1 111 1111
1 000 0000
1 000 0000
Table 3. Extended Resolution Register
FRACTIONAL
TEMPERATURE
DIGITAL OUTPUT
0.000
0.125
0.250
0.375
0.500
0.625
0.750
0.875
000X XXXX
001X XXXX
010X XXXX
011X XXXX
100X XXXX
101X XXXX
110X XXXX
111X XXXX
When the conversion rate is greater than 1Hz, tempera-
ture data can be read from the read internal tempera-
ture (00h) and read external temperature (01h)
registers. The temperature data format is 7 bits plus
sign in two’s-complement form for each channel, with
the LSB representing 1°C (Table 2), transmitted MSB
first. When the conversion rate is less than 1Hz, the
extended data can be read from the read external
extended temperature register (10h) and the read inter-
nal extended temperature register (11h), and the first 3
bits of the register represent 1/2, 1/4, and 1/8 of a
degree. Measurements are offset by +1/2°C to mini-
mize quantization errors; for example, +99.6°C is
reported as +100°C.
When the conversion rate is 1Hz or less, the first 8 bits
of temperature data can be read from the read internal
temperature (00h) and read external temperature (01h)
registers, the same as for faster conversion rates. An
additional 3 bits can be read from the read external
extended temperature and read internal extended tem-
perature registers, which extend the resolution to
0.125°C per LSB (Table 3).
If a conversion ends after reading the main register but
before reading the extended register, the extended
register will contain the 3LSBs from the new conversion
while the main register will contain the 8MSBs from the
previous conversion. The extended data in this case
will be meaningless. To avoid this problem, read
extended resolution temperature data using one of the
following approaches:
1) Put the MAX6654 into standby mode by setting bit 6
of the configuration register to 1. Initiate a one-shot
conversion using Command Byte 0Fh. When this
conversion is complete, read the contents of the
temperature data registers.
2) If the MAX6654 is in run mode and the conversion
rate is not set to either 1Hz or 8Hz, read the Status
Byte. If the BUSY bit indicates that a conversion is
in progress, wait until the conversion is complete as
indicated by the BUSY bit. Then immediately read
the contents of the temperature data registers. If no
conversion is in progress, the data can be read
within a few µs, which is a sufficiently short period
to ensure that a new conversion can’t be completed
until after the data has been read.
Note: Extended resolution applies only for conversion
speeds of 1Hz and below.
Alarm Threshold Registers
Four registers store alarm threshold data, with high-
temperature (THIGH) and low-temperature (TLOW) reg-
isters for each A/D channel. If either measured
temperature equals or exceeds the corresponding
alarm threshold value, an ALERT interrupt is asserted.
The POR state of both THIGH registers is full scale
(0111 1111, or +127°C). The POR state of both TLOW
registers is 1100 1001 or -55°C.
Diode Fault Alarm
There is a continuity fault detector at DXP that detects
whether the remote diode has an open-circuit condition
or if DXP is shorted to DXN, GND, or VCC. If an open
circuit exists, then the temperature register will be
loaded with 1000 0000, and bit 3 of the status register
will be set to 1 at the end of a conversion. This means
that immediately after POR the status byte will indicate
no fault is present until the end of the first conversion.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX6654MEE.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX6654MEE | 1C Accurate Remote/Local Temperature Sensor with SMBus Serial Interface | Maxim Integrated |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |