MAX6654_13 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – 1°C Accurate Remote/Local Temperature Sensor with SMBus Serial Interface

MAX6654
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), 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 conver-
sion 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, providing 10-bit-plus-sign
resolution with a 0.125°C LSB. Single-shot conversions
also have 0.125°C per LSB resolution when the conver-
sion 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.
Desktop Computers
Notebook Computers
Servers
Thin Clients
Applications
Workstations
Test and Measurement
Multichip Modules
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
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX6654MEE+ -55°C to +125°C 16 QSOP
+Denotes a lead(Pb)-free/RoHS-compliant part.
Typical Operating Circuit
0.1µF
+3.3V SUPPLY
CPU
V_CC 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
V_CC 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
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-1836; Rev 4; 6/13