TC648 Microchip, TC648 Datasheet - Page 9

• Manufacturer Part Number: TC648
• Description: Fan Speed Controller
• Manufacturer: Microchip

5.0
Designing with the TC648 involves the following:
(1) The temperature
(2) The auto-shutdown temperature must be set with
(3) The output drive transistor and base resistor must
(4) If reset/shutdown capability is desired, the drive
The TC642 demonstration and prototyping board
(TC642DEMO)
(TC642EV) provide working examples of TC648 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
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.
a voltage divider on V
be selected.
requirements of the external signal or circuit must
be considered.
TYPICAL APPLICATIONS
NOTES:
and
*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.
the
sensor
R
+5V
R
AS
1
2
(if used).
R
R
TC642
3
4
network
C
0.01 µF
C
0.01 µF
NTC
B
C F
1 µF
B
Evaluation
must
IN
V
V
for 0%
AS
C
IN
F
Kit
be
V
DD
TC648
GND
analysis. At the very least, anyone contemplating a
design using the TC648 should consult the documen-
tation
TC642DEMO (DS21401). Figure 5-1 shows the base
schematic for the TC642DEMO.
An Excel-based spreadsheet is also available for
designing the thermistor network for the TC64X fan
controllers. This file (TC64X Therm) is available for
downloading
www.microchip.com.
C
1 µF
B
V
for
OUT
OTF
NC
both the TC642EV
from
the
Over-
Temperature
Interrupt
Microchip
R
BASE
(DS21403)
DS21448C-page 9
TC648
website
+12V
Fan
Q
1
and
at