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.
General Description
The MAX6690†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-connected transistor—typically a low-cost, easily mounted
2N3904 NPN type or 2N3906 PNP type—that replaces
conventional thermistors or thermocouples. Remote
accuracy is ±2°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
TM
), 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 conversion 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-bitplus-sign byte with a 1°C LSB. When the conversion rate
is 1Hz or slower, the MAX6690 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 conversion rate is 1Hz or slower.
A parasitic resistance cancellation (PRC) mode can also
be invoked for conversion rates of 1Hz or slower by setting 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 MAX6690 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 MAX6690 is available in a small, 16-pin QSOP surface-mount package.
________________________Applications
Features
♦ High Accuracy ±2°C (max) from +70°C to +100°C
(Remote)
♦ 11-Bit, 0.125°C Resolution
♦ Dual Channel: Measures Remote and Local
Temperature
♦ No Calibration Required
♦ Programmable Under/Overtemperature Alarms
♦ I
2
C™-Compatible/SMBus Interface
♦ +3V to +5.5V Supply Range
MAX6690
2°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
________________________________________________________________ Maxim Integrated Products 1
V
CC
DXP
CPU
DXN
STBY
10kΩ EACH
CLOCK
DATA
INTERRUPT TO µC
+3V TO +5V SUPPLY
200Ω
0.1µF
SMBCLK
SMBDATA
ALERT
GND
ADD0 ADD1
2200pF
MAX6690
Typical Operating Circuit
19-2190; Rev 0; 10/01
Ordering Information
Desktop Computers
Notebook Computers
Servers
Thin Clients
Workstations
Test and Measurement
Multichip Modules
SMBus is a trademark of Intel Corp.
I
2
C is a trademark of Philips Corp.
†
Patents pending.
PART TEMP. RANGE PIN-PACKAGE
MAX6690MEE
-55°C to +125°C
TOP VIEW
1
N.C. N.C.
2
V
CC
DXP
3
MAX6690
4
DXN
N.C.
5
ADD1
6
GND
7
GND
8
QSOP
16
15
14
13
12
11
10
9
STBY
SMBCLK
N.C.
SMBDATA
ALERT
ADD0
N.C.
MAX6690
2°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= +3V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V and TA= +25°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.
(All voltages are referenced to GND unless otherwise noted.)
V
CC
..........................................................................-0.3V to +6V
DXP, ADD_ .................................................-0.3V to (V
CC
+ 0.3V)
DXN ......................................................................-0.3V to +0.8V
SMBCLK, SMBDATA, ALERT, STBY.. ......................-0.3V to +6V
SMBDATA, ALERT Current .................................-1mA to +50mA
DXN Current ......................................................................±1mA
ESD Protection (all pins, Human Body Model). .................2000V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.30mW/°C above +70°C).........667mW
Operating Temperature Range ........................-55°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range ............................-65°C to +165°C
Lead Temperature (soldering, 10s) .................................+300°C
TEMPERATURE-TO-DIGITAL CONVERTER
Accuracy (Local Sensor)
Line Regulation 0.2 0.5 °C
Resolution (Legacy Mode) Conversion rate >1Hz
Resolution (Extended Mode) Conversion rate ≤1Hz
Undervoltage Lockout
Threshold
Undervoltage Lockout
Hysteresis
Supply Voltage Range V
P ow er - O n Reset ( P O R) Thr eshol d VCC, falling edge +1.5 +2.0 +2.5 V
POR Threshold Hysteresis +90 mV
Standby Current SMBus static +3 +10 µA
Operating Current During conversion +0.55 +1 mA
Average Operating Current
Conversion Time t
Conversion Timing Error ±25 %
Remote-Diode Current I
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
+60°C ≤ T
0°C ≤ T
-55°C ≤ T
+ 70° C ≤ T
0°C ≤ T
- 55°C ≤ T
≤ +100°C, VCC = +3.3V -2.5 +2.5
A
≤ +100°C, VCC = +3.3V -3.5 +3.5
A
≤ +120°C, VCC = +3.3V -5.0 +5.0
A
≤ + 100° C , V
R J
≤ +100°C, VCC = +3.3V (Note 1) -3.5 +3.5Accuracy (Remote Sensor)
RJ
≤ +120°C , V
RJ
= + 3.3V ( N ote 1) -2 +2
C C
= + 3.3V ( Notes 1, 2) -5 +5
C C
+1 °C
+8 Bits
+0.125 °C
+11 Bits
V
input, disables A/D conversion,
UVLO
CC
rising edge
+2.60 +2.80 +2.95 V
+90 mV
CC
+3.0 +5.5 V
0.25 conversion/s (Note 3) +40 +70
2 conversion/s (Note 3) +150 +250
CONV
RJ
From stop bit to conversion completed, in
legacy mode (Note 3)
High level +80 +100 +120
Low level +8 +10 +12
+95 +125 +156 ms
°C
°C
µA
µA
MAX6690
2°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +3V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V and TA= +25°C.)
Note 1: +25°C ≤ TA≤ +85°C.
Note 2: If both the MAX6690 and the remote junction are below T
A
= -20°C, then VCC> 3.15V.
Note 3: The conversion time doubles for the extended resolution mode. This causes the average operating current to approximately
double.
Note 4: The serial interface resets when SMBCLK is low for more than t
TIMEOUT
.
Note 5: Note that a transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SMBCLK’s
falling edge.
Logic Input Low Voltage V
Logic Input High Voltage V
Input Leakage Current I
Output Low Sink Current I
Input Capacitance C
Output High Leakage Current VOH = +5.5V +1 µA
Serial Clock Frequency f
Bus Free Time Between STOP
and START Conditions
START Condition Setup Time +4.7 µs
Repeat START Condition Setup
Time
START Condition Hold Time t
STOP Condition Setup Time t
Clock Low Period t
Clock High Period t
Data Setup Time t
Data Hold Time t
Receive SCL/SDA Rise Time t
Receive SCL/SDA Fall Time t
SMBus Timeout t
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
VCC = +3.0V to +5.5V +0.8 V
IL
VCC = +3.0V +2.2
IH
VCC = +5.5V +2.6
V
LEAK
OL
IN
SCL
t
BUF
t
SU:STA
HD:STA
SU:STO
LOW
HIGH
SU:DAT
HD:DAT
R
F
TIMEOUT
= GND or V
IN
VOL = +0.6V +6
V
= +0.4V +1
OL
(Note 4) 0 +100 kHz
90% to 90% +50 µs
10% of SMBDATA to 90% of SMBCLK +4 µs
90% of SMBCLK to 10% of SMBDATA662 +4 µs
10% to 10% +4.7 µs
90% to 90% +4 µs
90% of SMBDATA to 10% of SMBCLK +250 ns
(Note 5) 0 µs
SMBDATA and SMBCLK time low for reset
of serial interface
CC
+5 pF
+4.7 µs
+25 +40 ms
±2µA
+1 µs
+300 ns
V
mA
MAX6690
2°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VCC= +3.3V to +5.5V, TA= +25°C, unless otherwise noted.)
-2
-1
1
0
2
-50 -10 10 30 50-30 70 90 110 130 150
TEMPERATURE ERROR vs.
REMOTE-DIODE TEMPERATURE
MAX6690 toc01
TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
FAIRCHILD 2N3904
1 10k 1M100 100M
TEMPERATURE ERROR vs.
POWER-SUPPLY NOISE FREQUENCY
MAX6690 toc02
FREQUENCY (Hz)
TEMPERATURE ERROR (°C)
0
4
8
12
16
VIN = 500mVp-p LOCAL
VIN = 500mVp-p REMOTE
3
0
1k 10M
TEMPERATURE ERROR vs.
COMMON-MODE NOISE FREQUENCY
1
2
MAX6690 toc03
FREQUENCY (Hz)
TEMPERATURE ERROR (°C)
100k
0
2
1
3
6
7
5
4
8
0 2030405010 60 70 80 90 100
TEMPERATURE ERROR vs.
DXP-DXN CAPACITANCE
MAX6690 toc04
DXP-DXN CAPACITANCE (nF)
TEMPERATURE ERROR (°C)
VCC = +5V
40
70
60
50
80
90
100
3.0 3.83.63.2 3.4 4.0 4.2 4.4 4.6 4.8 5.0
STANDBY SUPPLY CURRENT vs.
SUPPLY VOLTAGE
MAX6690 toc05
SUPPLY VOLTAGE (V)
STANDBY SUPPLY CURRENT (µA)
MAX6690
2°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
_______________________________________________________________________________________ 5
Pin Description
PIN NAME FUNCTION
1, 5, 9, 13, 16 N.C. No Connection. Not internally connected. May be used for PC board trace routing.
2V
3 DXP
4 DXN
6 ADD1 SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.
7, 8 GND Ground
10 ADD0 SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.
11 ALERT SMBus Alert (Interrupt) Output. Open drain.
12 SMBDATA SMBus Serial-Data Input/Output. Open drain.
14 SMBCLK SMBus Serial-Clock Input
15 STBY
CC
Supply Voltage Input. +3.0V to +5.5V. Bypass to GND with a 0.1µF capacitor. A 200Ω series
resistor is recommended but not required for additional noise filtering.
Combined Current Source and ADC Positive Input for Remote-Junction Channel. If a remotesensing junction is not used, connect DXP to DXN.
Combined Current Sink and ADC Negative Input. DXN is internally biased to a diode voltage above
ground.
Hardware Standby Input. Temperature and comparison threshold data are retained in standby
mode. Low = standby mode, high = operating mode.