TC649 Microchip, TC649 Datasheet - Page 9

• Manufacturer Part Number: TC649
• Description: PWM Fan Speed Controller
• Manufacturer: Microchip

5.0
Designing with the TC649 involves the following:
(1) The temperature
(2) The auto-shutdown temperature must be set
(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:
2002 Microchip Technology Inc.
Shutdown**
configured to deliver 1.25V to 2.65V on V
to 100% of the temperature range to be regulated.
with a voltage divider on V
must be selected.
be designed for maximum efficiency while
delivering adequate signal amplitude.
ments of the external signal or circuit must be
considered.
Notes:
TYPICAL APPLICATIONS
*See cautions regarding Latch-up Considerations in Section 5.0, "Typical Applications".
**Optional. See Section 5.0, "Typical Applications" for details.
+5V*
Typical Application Circuit.
sensor network must be
R
+5V
R
1
2
SENSE
R 3
R
AS
4
.
C
0.01 µF
and C
C
0.01 µF
B
NTC
B
C
1 µF
F
SENSE
V
V
C
IN
AS
IN
F
for 0%
, must
V
DD
TC649
GND
+
The TC642 demonstration and prototyping board
(TC642DEMO)
(TC642EV) provide working examples of TC649 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 TC649 should consult the documen-
tation for both TC642EV (DS21403) and TC642DEMO
(DS21401).Figure 5-1 shows the base schematic for
the TC642DEMO.
C
1 µF
B
SENSE
FAULT
V
OUT
and
the
C
Fan Fault
Shutdown
SENSE
TC642
R
BASE
DS21449C-page 9
TC649
R
Evaluation
SENSE
+12V
Fan
Q
1
Kit