Rainbow Electronics MAX1989 - Manual

________________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.
________________________Applications
____________________________Features
♦ 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
±2°C (+60°C to +100°C, Local)
±3°C (-40°C to +125°C, Local)
±3°C (+60°C to +100°C, Remote)
♦ 3µA (typ) Standby Supply Current
♦ 700µA (max) Supply Current
♦ Small, 16-Pin QSOP Package
MAX1668/MAX1805/MAX1989
†
Multichannel Remote/Local
Temperature Sensors
________________________________________________________________ Maxim Integrated Products 1
SMBCLK
ADD0 ADD1
V CC STBY
GND
ALERT
SMBDATA
DXP1
DXP4
DXN4
INTERRUPT
TO
µC
3V TO 5.5V
200 Ω
0.1 µF
CLOCK
10k Ω EACH
DATA
DXN1
2200pF
2200pF
* DIODE-CONNECTED TRANSISTOR
*
*
MAX1668
MAX1805
MAX1989
Pin Configuration
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
DXP1 GND
STBY
SMBCLK
SMBDATA
ALERT
ADD0
ADD1
V CC
TOP VIEW
MAX1668
MAX1805
MAX1989
QSOP
DXN1
DXP2
(N.C.) DXN3
DXN2
(N.C.) DXP3
(N.C.) DXP4
( ) ARE FOR MAX1805.
(N.C.) DXN4
Typical Operating Circuit
19-1766; Rev 1; 8/02
PART
MAX1668MEE -55°C to +125°C
TEMP RANGE PIN-PACKAGE
16 QSOP
_______________Ordering Information
SMBus is a trademark of Intel Corp. †Patents Pending
MAX1805MEE -55°C to +125°C 16 QSOP
Desktop and Notebook
Computers
LAN Servers
Industrial Controls
Central-Office Telecom
Equipment
Test and Measurement
Multichip Modules
MAX1989MEE -55°C to +125°C 16 QSOP
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.