MAX6639FAEE+T Maxim Integrated Products, MAX6639FAEE+T Datasheet - Page 18

• Manufacturer Part Number: MAX6639FAEE+T
• Description: IC 2CH TEMP MONITOR 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6639FAEE+T

• Function: Fan Control, Temp Monitor
• Topology: ADC, PWM Generator, Tach Counter
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 150°C, External Sensor
• Output Type: I²C™/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: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2-Channel Temperature Monitor with Dual,
Automatic, PWM Fan-Speed Controller
1) Write 02h to register 11h to set the PWM output to
2) Write 4Bh to register 22h to set the minimum RPM to
3) Write 5Eh to register 24h to set the pulses per revo-
4) Write 19h to register 28h to set the fan-start temper-
5) Write D2h to register 10h to start automatic
Temperature accuracy depends upon having a good-
quality, diode-connected, small-signal transistor.
Accuracy has been experimentally verified for all the
devices listed in Table 12. The MAX6639 can also
directly measure the die temperature of CPUs and
other ICs with on-board temperature-sensing diodes.
The transistor must be a small-signal type with a rela-
tively high forward voltage. This ensures that the input
voltage is within the A/D input voltage range. The for-
ward voltage must be greater than 0.25V at 10µA at the
highest expected temperature. The forward voltage
must be less than 0.95V at 100µA at the lowest expect-
ed temperature. The base resistance has to be less
than 100Ω. Tight specification of forward-current gain
(+50 to +150, for example) indicates that the manufac-
turer has good process control and that the devices
have consistent characteristics.
The accuracy of the remote temperature measurements
depends on the ideality factor (n) of the remote diode
(actually a transistor). The MAX6639 is optimized for n
= 1.008, for Intel
Table 11. Summary of Fan-Drive Options
Intel and Pentium are registered trademarks of Intel Corp.
AMD Athlon is a registered trademark of Advanced Micro
Devices, Inc.
18
(2 Pulses per Revolution) Fan in Automatic
FIGURE
drive the n-channel MOSFET.
3200.
lution to 2 and to set the maximum RPM speed to
8000RPM.
ature to +25°C.
RPM mode.
______________________________________________________________________________________
10
RPM Mode Using the Circuit of Figure 7
6
7
8
9
Quick-Start Guide for 8000RPM 4-Pole
High-side PWM drive
Low-side PWM drive
High-side PWM drive with keep-alive supply
High-side linear supply
4-wire fan with PWM speed-control input
Remote-Diode Considerations
®
Pentium
Effect of Ideality Factor
DESCRIPTION
®
II and AMD Athlon
®
MP
PULSE STRETCHING
compatibility, and the MAX6639F is optimized for n =
1.021 for Penryn compatibiliy. If a sense transistor with
a different ideality factor is used, the output data is dif-
ferent. 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
MAX6639 is 1.008. As an example, assume the
MAX6639 is configured 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 +82.91°C (356.02K), which is an
error of -2.13°C.
Table 12. Remote-Sensor Transistor
Manufacturers
Central Semiconductor (USA)
Rohm Semiconductor (USA)
Samsung (Korea)
Siemens (Germany)
T
ACTUAL
Yes
Yes
No
No
No
MANUFACTURER
=
T
M
T
M
⎛
⎜
⎝
NOMINAL
n
=
NOMINAL
PWM FREQUENCY
T
n
ACTUAL
1
High
High
Low
Low
Low
is used to measure the tem-
⎞
⎟ =
⎠
⎛
⎜
⎝
M
T
n
M
NOMINAL
can be corrected using:
⎛
⎜
⎝
n
1 008
1 002
1
.
.
PWM POLARITY
MODEL NO.
KST3906-TF
⎞
⎟ =
⎠
CMPT3906
SMBT3906
⎞
⎟
⎠
SST3906
Negative
Negative
T
Positive
Positive
Positive
M
( .
1 00599
1
)
.