19-1766; Rev 1; 8/02
Multichannel Remote/Local
Temperature Sensors
________________General Description
____________________________Features
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 3ꢀ° for multiple transistor manu-
facturers, with no calibration needed. The remote chan-
nels can also measure the die temperature of other I°s,
such as microprocessors, that contain an on-chip,
diode-connected transistor.
ꢀ Multichannel
4 Remote, 1 Local (MAX1668/MAX1989)
2 Remote, 1 Local (MAX1805)
ꢀ No Calibration Required
ꢀ SMBus 2-Wire Serial Interface
ꢀ Programmable Under/Overtemperature Alarms
ꢀ Supports SMBus Alert Response
ꢀ Accuracy
±2ꢀC (ꢁ60ꢀC to ꢁ100ꢀC, Local)
±±ꢀC (-40ꢀC to ꢁ125ꢀC, Local)
±±ꢀC (ꢁ60ꢀC to ꢁ100ꢀC, Remote)
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
1ꢀ°, in two’s-complement format.
ꢀ ±µA (typ) Standby Supply Current
ꢀ 700µA (max) Supply Current
ꢀ Small, 16-Pin QSOP Package
The MAX1668/MAX1805/MAX1989 are available in
small, 16-pin QSOP surface-mount packages.
________________________Applications
_______________Ordering Information
Desktop and Notebook
°omputers
°entral-Office Telecom
Equipment
PART
TEMP RANGE
-55ꢀ° to +125ꢀ°
-55ꢀ° to +125ꢀ°
-55ꢀ° to +125ꢀ°
PIN-PACKAGE
16 QSOP
MAX1668MEE
MAX1805MEE
MAX1989MEE
LAN Servers
Test and Measurement
Multichip Modules
16 QSOP
Industrial °ontrols
16 QSOP
Pin Configuration
Typical Operating Circuit
3V TO 5.5V
0.1µF
200Ω
TOP VIEW
DXP1
DXN1
1
2
3
4
5
6
7
8
16 GND
V
STBY
CC
10kΩ EACH
15 STBY
14 SMBCLK
MAX1668
MAX1805
MAX1989
DXP2
DXP1
CLOCK
DATA
SMBCLK
DXN2
MAX1668
13 SMBDATA
12 ALERT
11 ADD0
2200pF
MAX1805
MAX1989
SMBDATA
ALERT
(N.C.) DXP3
(N.C.) DXN3
(N.C.) DXP4
(N.C.) DXN4
DXN1
*
INTERRUPT
TO µC
10 ADD1
DXP4
DXN4
2200pF
9
V
CC
*
ADD0 ADD1 GND
QSOP
( ) ARE FOR MAX1805.
*
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.