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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
†Pg
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.
Multichannel Remote/Local
Temperature Sensors
MAX1668/MAX1805/MAX1989
†
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ..............................................................-0.3V to +6V
DXP_, ADD_, STBY to GND........................-0.3V to (V
CC
+ 0.3V)
DXN_ to GND ........................................................-0.3V to +0.8V
SMBCLK, SMBDATA,
ALERT
to GND ......................-0.3V to +6V
SMBDATA,
ALERT
Current .................................-1mA to +50mA
DXN_ Current......................................................................±1mA
Continuous Power Dissipation (T
A
= +70°C)
QSOP (derate 8.30mW/°C above +70°C) ....................667mW
TSSOP (derate 9.40mW/°C above +70°C) ..................755mW
Operating Temperature Range .........................-55°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +3.3V,
STBY
= V
CC
, configuration byte = X0XXXX00,
T
A
= 0°C to +125°C,
unless otherwise noted.)
PARAMETER
ADC AND POWER SUPPLY
Temperature Resolution (Note 1)
Initial Temperature Error,
Local Diode (Note 2)
Temperature Error, Remote Diode
(Notes 2, 3)
Temperature Error, Local Diode
(Notes 1, 2)
Supply Voltage Range
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Power-On Reset (POR) Threshold
POR Threshold Hysteresis
Logic inputs
forced to V
CC
or GND
SMBus static
Hardware or software standby,
SMBCLK at 10kHz
V
CC
, falling edge
1.3
V
CC
input, disables A/D conversion, rising edge
Monotonicity guaranteed
T
A
= +60°C to +100°C
T
A
= 0°C to +125°C
T
R
= +60°C to +100°C
T
R
= -55°C to +125°C
Including long-term drift
T
A
= +60°C to +100°C
T
A
= 0°C to +85°C
8
-2
-3
-3
-5
-2.5
-3.5
3.0
2.60
2.8
50
1.8
50
3
5
400
260
70
7
320
100
10
200
50
0.7
ADD0, ADD1; momentary upon power-on reset
160
V
µA
10
µA
12
700
380
130
13
µA
µA
ms
2.3
+2
+3
+3
+5
+2.5
+3.5
5.5
2.95
Bits
°C
°C
°C
V
V
mV
V
mV
CONDITIONS
MIN
TYP
MAX
UNITS
Standby Supply Current
Average Operating Supply Current
Conversion Time
Average measured over 4s; logic inputs forced
V
CC
or GND
From stop bit to conversion complete (all channels)
High level (POR state)
Low level (POR state)
Configuration byte =
X0XXXX10, high level
Configuration byte =
X0XXXX01, high level
Remote-Diode Source Current
DXP_ forced to 1.5V
DXN_ Source Voltage
Address Pin Bias Current
2
_______________________________________________________________________________________
Multichannel Remote/Local
Temperature Sensors
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.3V,
STBY
= V
CC
, configuration byte = X0XXXX00,
T
A
= 0°C to +125°C,
unless otherwise noted.)
PARAMETER
SMBus INTERFACE
Logic Input High Voltage
Logic Input Low Voltage
Logic Output Low Sink Current
ALERT
Output High Leakage
Current
Logic Input Current
SMBus Input Capacitance
SMBus Clock Frequency
SMBCLK Clock Low Time
SMBCLK Clock High Time
SMBus Start-Condition Setup Time
SMBus Repeated Start-Condition
Setup Time
SMBus Start-Condition Hold Time
SMBus Stop-Condition Setup Time
SMBus Data Valid to SMBCLK
Rising-Edge Time
SMBus Data-Hold Time
SMBCLK Falling Edge to SMBus
Data-Valid Time
t
SU:STA
, 90% to 90% points
t
HD:STA
, 10% of SMBDATA to 90% of SMBCLK
t
SU:STO
, 90% of SMBCLK to 10% of SMBDATA
t
SU:DAT
, 10% or 90% of SMBDATA to 10% of SMBCLK
t
HD:DAT
, slave receive (Note 5)
Master clocking in data
STBY,
SMBCLK, SMBDATA; V
CC
= 3V to 5.5V
STBY,
SMBCLK, SMBDATA; V
CC
= 3V to 5.5V
ALERT,
SMBDATA forced to 0.4V
ALERT
forced to 5.5V
Logic inputs forced to V
CC
or GND
SMBCLK, SMBDATA
(Note 4)
t
LOW
, 10% to 10% points
t
HIGH
, 90% to 90% points
DC
4.7
4
4.7
250
4
4
250
0
1
-1
5
100
6
1
+1
2.2
0.8
V
V
mA
µA
µA
pF
kHz
µs
µs
µs
ns
µs
µs
ns
ns
µs
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1668/MAX1805/MAX1989
†
ELECTRICAL CHARACTERISTICS
(V
CC
= +5V,
STBY
= V
CC
, configuration byte = X0XXXX00,
T
A
= -55°C to +125°C,
unless otherwise noted.) (Note 6)
PARAMETER
ADC AND POWER SUPPLY
Temperature Resolution
Initial Temperature Error,
Local Diode (Note 2)
Temperature Error, Remote Diode
(Notes 2, 3)
Supply-Voltage Range
Conversion Time
From stop bit to conversion complete (both channels)
Monotonicity guaranteed
T
A
= +60°C to +100°C
T
A
= -55°C to +125°C
T
R
= +60°C to +100°C
T
R
= -55°C to +125°C
8
-2
-3
-3
-5
4.5
260
+2
+3
+3
+5
5.5
380
Bits
°C
°C
V
ms
CONDITIONS
MIN
TYP
MAX
UNITS
_______________________________________________________________________________________
3
Multichannel Remote/Local
Temperature Sensors
MAX1668/MAX1805/MAX1989
†
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V,
STBY
= V
CC
, configuration byte = X0XXXX00,
T
A
= -55°C to +125°C,
unless otherwise noted.) (Note 6)
PARAMETER
SMBus INTERFACE
Logic Input High Voltage
Logic Input Low Voltage
Logic Output Low Sink Current
ALERT
Output High Leakage
Current
Logic Input Current
STBY,
SMBCLK, SMBDATA; V
CC
= 4.5V to 5.5V
STBY,
SMBCLK, SMBDATA; V
CC
= 4.5V to 5.5V
ALERT,
SMBDATA forced to 0.4V
ALERT
forced to 5.5V
Logic inputs forced to V
CC
or GND
-2
6
1
+2
2.4
0.8
V
V
mA
µA
µA
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Guaranteed by design, but not production tested.
Note 2:
Quantization error is not included in specifications for temperature accuracy. For example, if the MAX1668/MAX1805/
MAX1989 device temperature is exactly +66.7°C, the ADC may report +66°C, +67°C, or +68°C (due to the quantization
error plus the +0.5°C offset used for rounding up) and still be within the guaranteed ±1°C error limits for the +60°C to
+100°C temperature range. See Table 2.
Note 3:
A remote diode is any diode-connected transistor from Table 1. T
R
is the junction temperature of the remote diode. See the
Remote-Diode Selection
section for remote-diode forward-voltage requirements.
Note 4:
The SMBus logic block is a static design that works with clock frequencies down to DC. While slow operation is possible, it
violates the 10kHz minimum clock frequency and SMBus specifications, and can monopolize the bus.
Note 5:
Note that a transition must internally provide at least a hold time in order to bridge the undefined region (300ns max) of
SMBCLK’s falling edge t
HD:DAT.
Note 6:
Specifications from -55°C to +125°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(Typical
Operating Circuit,
V
CC
= +5V,
STBY
= V
CC
, configuration byte = X0XXXX00, T
A
= +25°C, unless otherwise noted.)
TEMPERATURE ERROR
vs. PC BOARD RESISTANCE
MAX1668/1805 toc01
TEMPERATURE ERROR
vs. TEMPERATURE
MAX1668/1805 toc02
TEMPERATURE ERROR
vs. SUPPLY NOISE FREQUENCY
WITH V
CC
0.1µF CAPACITOR REMOVED
2200pF BETWEEN DXN_ AND DXP_
250mV
P-P
16
12
8
4
0
MAX1668/1805 toc03
20
4
3
TEMPERATURE ERROR (°C)
NPN (CMPT3904)
2
1
0
-1
INTERNAL
PNP (CMPT3906)
24
20
TEMPERATURE ERROR (°C)
TEMPERATURE ERROR (°C)
10
PATH = DXP_ TO GND
0
-10
PATH = DXP_ TO V
CC
(5V)
100mV
P-P
-20
1
10
LEAKAGE RESISTANCE (MΩ)
100
-2
-50 -30 -10
10
30
50
70
90
110
TEMPERATURE (°C)
0.1
1
10
100
FREQUENCY (MHz)
4
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