TC647 Microchip, TC647 Datasheet - Page 4

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

TC647
2.0
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1:
2.1
The thermistor network (or other temperature sensor)
connects to the V
2.65V (typical) on this pin drives an active duty cycle of
0% to 100% on the V
2.2
C
timing capacitor. The recommended C
30 Hz PWM operation.
DS21447C-page 4
1
2
3
4
5
6
7
8
Pin No.
F
is the positive terminal for the PWM ramp generator
PIN DESCRIPTIONS
Analog Input (V
Analog Output (C
Symbol
SENSE
FAULT
GND
V
V
V
V
C
OUT
MIN
DD
IN
F
IN
PIN FUNCTION TABLE
input. A voltage range of 1.25V to
OUT
Analog Input
Analog Output
Analog Input
Ground Terminal
Analog Input
Digital (Open Collector) Output
Digital Output
Power Supply Input
pin.
IN
Description
)
F
)
F
is 1 µF for
2.3
An external resistor divider connected to the V
sets the minimum fan speed by fixing the minimum
PWM duty cycle (1.25V to 2.65V = 0% to 100%, typi-
cal). The TC647 enters shutdown mode when V
V
and supply current falls to 25 µA (typical). The TC647
exits shutdown mode when V
Section 5.0, “Typical Applications”, for more details.
2.4
GND denotes the ground terminal.
2.5
Pulses are detected at the SENSE pin as fan rotation
chops the current through a sense resistor. The
absence of pulses indicates a fault.
2.6
The FAULT line goes low to indicate a fault condition.
When FAULT goes low due to a fan fault condition, the
device is latched in shutdown mode until deliberately
cleared or until power is cycled. FAULT may be con-
nected to V
2.7
V
the base of an external NPN transistor (via an appropri-
ate base resistor) or the gate of an N-channel MOS-
FET. This output has asymmetrical drive (see
Section 1.0, “Electrical Characteristics”).
2.8
V
(see Section 1.0, “Electrical Characteristics”).
SHDN
OUT
DD
may be independent of the fan’s power supply
is an active high complimentary output that drives
. During shutdown, the FAULT output is inactive
Analog Input (V
Ground (GND)
Analog Input (SENSE)
Digital Output (FAULT)
Digital Output (V
Power Supply Input (V
MIN
if a hard shutdown is desired.
2002 Microchip Technology Inc.
MIN
OUT
)
MIN
)
DD
)
V
REL
MIN
. See
MIN
input