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.
____________________________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
MAX1668/MAX1805/MAX1989
†
_______________Ordering Information
________________________Applications
Desktop and Notebook
Computers
LAN Servers
Industrial Controls
Central-Office Telecom
Equipment
Test and Measurement
Multichip Modules
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
16 GND
15 STBY
14 SMBCLK
Typical Operating Circuit
0.1µF
3V TO 5.5V
200Ω
V
CC
STBY
10kΩ EACH
MAX1668
MAX1805
MAX1989
MAX1668
MAX1805
MAX1989
13 SMBDATA
12 ALERT
11 ADD0
10 ADD1
9
V
CC
DXP1
2200pF
SMBCLK
SMBDATA
ALERT
CLOCK
DATA
INTERRUPT
TO
µC
*
DXN1
DXP4
2200pF
*
DXN4
ADD0 ADD1 GND
QSOP/TSSOP
( ) ARE FOR MAX1805.
*
DIODE-CONNECTED TRANSISTOR
†Patents
Pending
1
SMBus is a trademark of Intel 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.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
