MAX6693UP9A+ Maxim Integrated Products, MAX6693UP9A+ Datasheet - Page 14

• Manufacturer Part Number: MAX6693UP9A+
• Description: IC TEMP MONITOR 7CH 20-TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6693UP9A+

• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Buffer, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7-Channel Precision Temperature Monitor
with Beta Compensation
where temperature is measured in Kelvin and
n
an example, assume you want to use the MAX6693 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 +84.41°C (357.56K), an error of
-0.590°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 MAX6693 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
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 0Ω to 100Ω.
Table 6. Configuration 3 Register
14
T
NOMIMAL
ACTUAL
7 (MSB)
______________________________________________________________________________________
BIT
6
5
4
3
2
1
0
=
T
for channel 1 of the MAX6693 is 1.009. As
M
×
T
Series Resistance Cancellation
⎛
⎜
⎝
M
n
Mask OVERT 6
Mask OVERT 5
Mask OVERT 4
Mask OVERT 1
NOMINAL
=
T
Reserved
Reserved
Reserved
Reserved
n
ACTUAL
1
NAME
⎞
⎟ =
⎠
⎛
⎜
⎝
T
n
M
NOMINAL
×
⎛
⎜
⎝
n
1 009
1 002
1
.
.
STATE
POR
⎞
⎟ =
⎠
⎞
⎟
⎠
0
0
0
0
0
0
0
0
T
M
( .
1 00699
—
—
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.
)
The MAX6693 is optimized for use with a substrate PNP
remote-sensing transistor on the die of the target IC.
DXP1 connects to the emitter of the sensing transistor
and DXN1 connects to the base. The collector is
grounded. Such transistors can have very low beta
(less than 1) when built in processes with 65nm and
smaller geometries. Because of the very low beta, stan-
dard “remote diode” temperature sensors may exhibit
large errors when used with these transistors. Channel
1 of the MAX6693 incorporates a beta compensation
function that, when enabled, eliminates the effect of low
beta values. This function is enabled at power-up using
bit 2 of the configuration 1 register. Whenever low beta
compensation is enabled, series-resistance cancella-
tion must be enabled.
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 MAX6693. 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
FUNCTION
Discrete Remote Diodes
Beta Compensation
BE
char-