TC647 Microchip, TC647 Datasheet - Page 9

• Manufacturer Part Number: TC647
• Description: PWM Fan Speed Controller
• Manufacturer: Microchip

5.0
Designing with the TC647 involves the following:
(1) The temp sensor network must be configured to
(2) The minimum fan speed (V
(3) The output drive transistor and associated circuitry
(4) The SENSE network, R
(5) If shutdown capability is desired, the drive require-
FIGURE 5-1:
Shutdown
2002 Microchip Technology Inc.
Note: *See cautions regarding latch-up considerations in Section 5.0, "Typical Applications".
deliver 1.25V to 2.65V on V
the temperature range to be regulated.
must be selected.
be designed for maximum efficiency while
delivering adequate signal amplitude.
ments of the external signal or circuit must be
considered.
TYPICAL APPLICATIONS
(Optional)
Typical Application Circuit.
SENSE
+5V*
MIN
IN
) must be set.
and C
for 0% to 100% of
R 1
R 2
R 3
R 4
SENSE
C B
0.01 µF
C B
0.01 µF
NTC
C
1 µF
, must
F
3
2
1
V
V
MIN
C
IN
F
8
V
DD
The TC642 demonstration and prototyping board
(TC642DEMO)
(TC642EV) provide working examples of TC647 cir-
cuits and prototyping aids. The TC642DEMO is a
printed circuit board optimized for small size and ease
of inclusion into system prototypes. The TC642EV is a
larger board intended for benchtop development and
analysis. At the very least, anyone contemplating a
design using the TC647 should consult the documen-
tation for both TC642EV and (DS21403) and
TC642DEMO (DS21401). Figure 5-1 shows the base
schematic for the TC642DEMO.
TC647
GND
4
C B
1 µF
SENSE
FAULT
V OUT
and
6
7
5
the
C
Fan Fault
Shutdown
SENSE
TC642
R
BASE
DS21447C-page 9
TC647
Evaluation
R
SENSE
+12V
Fan
Q 1
Kit