TC642 Просмотр технического описания (PDF) - Microchip Technology
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TC642 Datasheet PDF : 28 Pages
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TC642
5.8 TC642 as a Microcontroller
Peripheral
In a system containing a microcontroller or other host
intelligence, the TC642 can be effectively managed as
a CPU peripheral. Routine fan control functions can be
performed by the TC642 without processor intervention.
The microcontroller receives temperature data from one
or more points throughout the system. It calculates a fan
operating speed based on an algorithm specifically
designed for the application at hand. The processor
controls fan speed using complementary port bits I/O1
through I/O3. Resistors R1 through R6 (5% tolerance)
form a crude 3-bit DAC that translates the 3-bit code
from the processor's outputs into a 1.6V DC control sig-
nal. A monolithic DAC or digital pot may be used
instead of the circuit shown in Figure 5-10.
With VMIN set to 1.8V, the TC642 has a minimum
operating speed of approximately 40% of full rated
speed when the processor's output code is 000[B].
Output codes 001[B] to 111[B] operate the fan from
roughly 40% to 100% of full speed. An open-drain
output from the processor (I/O0) can be used to reset
the TC642 following detection of a fault condition. The
FAULT output can be connected to the processor's
interrupt input, or to an I/O pin, for polled operation.
+5V
Analog or Digital
Temperature
Data from one or
more Sensors
Open-drain
Outputs
I/O0 (RESET) (Optional)
R1
I/O1 (MSB) 110 kΩ
CMOS
Outputs
I/O2
I/O3
R2
240 kΩ
R3
360 kΩ
CMOS
Microcontroller
(LSB)
R5
1.5 kΩ
+5V
R6
1 kΩ
CB
.01 µF
R4
R7
18 kΩ 33 kΩ
+5V
R8
18 kΩ
GND
INT
+12V
+5V
1
VIN
8
VDD CB +
1 µF
R9
2
+
CF
VOUT 7
800Ω
1 µF
TC642
+5V
R10
3
6 10 kΩ
VMIN
FAULT
CB
.01 µF
4 GND
5
SENSE
0.1 µF
Fan
2N2222A
R11
2.2Ω
FIGURE 5-10:
TC642 as a Microcontroller Peripheral.
DS21444C-page 16
2002 Microchip Technology Inc.
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