MAX6692MUA Maxim Integrated Products, MAX6692MUA Datasheet - Page 12

• Manufacturer Part Number: MAX6692MUA
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of MAX6692MUA

• Full Temp Accuracy: +/- 3 C
• Package / Case: uSOP
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 10 bit + Sign
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Output Type: Digital
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

(actually a transistor). The MAX6648/MAX6692 (not the
MAX6648Y/MAX6692Y) are optimized for n = 1.008,
which is the typical value for the Intel
the AMD Athlon MP model 6. If a sense transistor with a
different ideality factor is used, the output data is differ-
ent. Fortunately, the difference is predictable.
Assume a remote-diode sensor designed for a nominal
ideality factor n
perature of a diode with a different ideality factor n
The measured temperature T
where temperature is measured in Kelvin.
As mentioned above, the nominal ideality factor of the
MAX6648/MAX6692 is 1.008. As an example, assume
you want to use the MAX6648/MAX6692 with a CPU
that has an ideality factor of 1.002.
If the diode has no series resistance, the measured
data is related to the real temperature as follows:
For a real temperature of +85°C (358.15 K), the mea-
sured temperature is +82.91°C (356.02 K), which is an
error of -2.13°C.
Series resistance in a sense diode contributes addition-
al errors. For nominal diode currents of 10µA and
100µA, change in the measured voltage is:
Since 1°C corresponds to 198.6µV, series resistance
contributes a temperature offset of:
Assume that the diode being measured has a series
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
Intel and Pentium are registered trademarks of Intel Corp.
12
T
ACTUAL
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
=
ΔV
T
M
M
T
M
=
⎛
⎜
⎝
R
NOMINAL
=
n
S
NOMINAL
T
198 6
(
ACTUAL
100
90
n
1
.
μ
μ
Ω
V
A
μ
°
C
V
−
is used to measure the tem-
⎞
⎟ =
⎠
⎛
⎜
⎝
Effect of Series Resistance
10
=
n
M
NOMINAL
0 453
T
μ
M
.
A
can be corrected using:
n
)
1
⎛
⎜
⎝
=
1 008
1 002
°
90
.
.
C
Ω
®
μ ×
⎞
⎟
⎠
A R
Pentium
⎞
⎟ =
⎠
T
S
M
( .
1 00599
®
III and
1
)
.
resistance of 3Ω. The series resistance contributes an
offset of:
The effects of the ideality factor and series resistance
are additive. If the diode has an ideality factor of 1.002
and series resistance of 3Ω, the total offset can be cal-
culated by adding error due to series resistance with
error due to ideality factor:
for a diode temperature of +85°C.
In this example, the effect of the series resistance and
the ideality factor partially cancel each other.
For best accuracy, the discrete transistor should be a
small-signal device with its collector and base connect-
ed together. Table 9 lists examples of discrete transis-
tors that are appropriate for use with the MAX6648/
MAX6692.
The transistor must be a small-signal type with a rela-
tively high forward voltage; otherwise, the A/D input
voltage range can be violated. The forward voltage at
the highest expected temperature must be greater than
0.25V at 10µA, and at the lowest expected tempera-
ture, the forward voltage must be less than 0.95V at
100µA. Large power transistors must not be used.
Also, ensure that the base resistance is less than 100Ω.
Tight specifications for forward current gain (50 < ß
<150, for example) indicate that the manufacturer has
good process controls and that the devices have con-
sistent V
Small transistor geometries and specialized processes
can affect temperature measurement accuracy.
Parasitic series resistance can be higher, which
increases the measured temperature value. Beta may
Table 9. Remote-Sensor Transistor
Manufacturers
Note: Transistors must be diode connected (base shorted to
collector).
Central Semiconductor (USA)
Rohm Semiconductor (USA)
Samsung (Korea)
Siemens (Germany)
MANUFACTURER
Operation with 45nm Substrate PNPs
BE
characteristics.
1.36°C - 2.13°C = -0.77°C
3
Ω
×
0 453
.
°
Ω
C
=
1 36
.
°
C
MODEL NO.
KST3904-TF
CMPT3904
SMBT3904
SST3904