MAX6697UP9C Maxim Integrated Products, MAX6697UP9C Datasheet - Page 13

• Manufacturer Part Number: MAX6697UP9C
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of MAX6697UP9C

• Full Temp Accuracy: +/- 3 C
• Package / Case: TSSOP-20
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 11 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Output Type: Digital
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

remote-diode sensor designed for a nominal ideality
factor n
a diode with a different ideality factor n1. The measured
temperature T
where temperature is measured in Kelvin and
n
assume you want to use the MAX6697 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 (358.15K), the mea-
sured temperature is +82.87°C (356.02K), an error of
-2.13°C.
Some thermal diodes on high-power ICs can have
excessive series resistance, which can cause tempera-
ture measurement errors with conventional remote tem-
perature sensors. Channel 1 of the MAX6697 has a
series resistance cancellation feature (enabled by bit 3
of the configuration 1 register) that eliminates the effect
of diode series resistance. Set bit 3 to 1 if the series
resistance is large enough to affect the accuracy of
channel 1. The series resistance cancellation function
Table 6. Configuration 3 Register
NOMIMAL
T
ACTUAL
7(MSB)
BIT
6
5
4
3
2
1
0
NOMINAL
=
T
for the MAX6697 is 1.008. As an example,
M
M
×
T
Series Resistance Cancellation
7-Channel Precision Temperature Monitor
⎛
⎜
⎝
M
can be corrected using:
n
is used to measure the temperature of
NOMINAL
Mask OVERT 6
Mask OVERT 5
Mask OVERT 4
Mask OVERT 1
=
______________________________________________________________________________________
T
Reserved
Reserved
Reserved
Reserved
n
ACTUAL
NAME
1
⎞
⎟ =
⎠
⎛
⎜
⎝
T
M
n
NOMINAL
×
⎛
⎜
⎝
n
1 008
1 002
1
.
.
STATE
POR
⎞
⎟ =
⎠
⎞
⎟
⎠
0
0
0
0
0
0
0
0
T
M
( .
1 00599
—
—
Channel 6 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 6
OVERT.
Channel 5 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 5
OVERT.
Channel 4 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 4
OVERT.
—
—
Channel 1 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 1
OVERT.
)
increases the conversion time for channel 1 by 125ms.
This feature cancels the bulk resistance of the sensor
and any other resistance in series (wire, contact resis-
tance, etc.). The cancellation range is from 0 to 100Ω.
When the remote-sensing diode is a discrete transistor,
its collector and base must be connected together.
Table 10 lists examples of discrete transistors that are
appropriate for use with the MAX6697. The transistor
must be a small-signal type with a relatively high for-
ward 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 temperature, the for-
ward 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 specifica-
tions for forward current gain (50 < ß <150, for exam-
ple) indicate that the manufacturer has good process
controls and that the devices have consistent V
acteristics. Manufacturers of discrete transistors do not
normally specify or guarantee ideality factor. This is
normally not a problem since good-quality discrete
transistors tend to have ideality factors that fall within a
relatively narrow range. We have observed variations in
remote temperature readings of less than ±2°C with a
variety of discrete transistors. Still, it is good design
practice to verify good consistency of temperature
readings with several discrete transistors from any
manufacturer under consideration.
FUNCTION
Discrete Remote Diodes
BE
char-
13