TC649 Microchip, TC649 Datasheet - Page 4

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

TC649
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
down mode when V
FAULT output is inactive, and supply current falls to
25 µA (typical). The TC649 exits shutdown mode when
V
details.
2.2
C
timing capacitor. The recommended C
30 Hz PWM operation.
DS21449C-page 4
1
2
3
4
5
6
7
8
Pin No.
IN
F
is the positive terminal for the PWM ramp generator
V
REL
PIN DESCRIPTIONS
Analog Input (V
Analog Output (C
. See Section 5.0, “Typical Applications”, for
Symbol
SENSE
FAULT
V
GND
V
V
V
C
OUT
AS
DD
IN
F
IN
PIN FUNCTION TABLE
IN
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
V
pin. The TC649 enters shut-
SHDN.
IN
Descriptiion
)
F
During shutdown, the
)
F
is 1 µF for
2.3
An external resistor divider connected to the V
sets the auto-shutdown threshold. Auto-shutdown
occurs when V
restarted when V
“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 (R
The absence of pulses indicates a fault. See
Section 5.0, “Typical Applications”, for more details.
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.
2.7
V
the base of an external NPN transistor (via an appropri-
ate base resistor) or the gate of an N-channel
MOSFET. This output has asymmetrical drive (see
Section 1.0, “Electrical Characteristics”).
2.8
V
(see Section 1.0, “Electrical Characteristics”).
OUT
DD
may be independent of the fan’s power supply
is an active high complimentary output that drives
Analog Input (V
Ground (GND)
Analog Input (SENSE)
Digital Output (FAULT)
Digital Output (V
Power Supply Input (V
IN
IN
V
(V
AS
AS
2002 Microchip Technology Inc.
. The fan is automatically
+ V
AS
OUT
HAS
)
). See Section 5.0,
)
DD
)
AS
SENSE
input
).