TC648 Ver la hoja de datos (PDF) - Microchip Technology
Número de pieza
componentes Descripción
Fabricante
TC648 Datasheet PDF : 28 Pages
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2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
Pin No. Symbol
Description
1
VIN Analog Input
2
CF Analog Output
3
VAS Analog Input
4
GND Ground Terminal
5
NC No Internal Connection
6
OTF Digital (Open Collector) Output
7
VOUT Digital Output
8
VDD Power Supply Input
2.1 Analog Input (VIN)
The thermistor network (or other temperature sensor)
connects to the VIN input. A voltage range of 1.25V to
2.65V (typical) on this pin drives an active duty cycle of
0% to 100% on the VOUT pin (see Section 5.0, “Typical
Applications”, for more details).
2.2 Analog Output (CF)
CF is the positive terminal for the PWM ramp generator
timing capacitor. The recommended CF is 1 µF for
30 Hz PWM operation.
TC648
2.3 Analog Input (VAS)
An external resistor divider connected to the VAS input
sets the auto-shutdown threshold. Auto-shutdown
occurs when VIN ≤ VAS. During shutdown, supply
current falls to 25 µA (typical). The fan is automatically
restarted when VIN ≥ (VAS +VHAS) (see Section 5.0,
“Typical Applications” for more details).
2.4 Ground (GND)
GND denotes the ground Terminal.
2.5 No Connect
No internal connection.
2.6 Digital Output (OTF)
OTF goes low to indicate an over-temperature
condition. This occurs when the voltage at VIN > VOTF
(see Section 1.0, "Electrical Characteristics"). An over-
temperature indication is a non-latching condition.
2.7 Digital Output (VOUT)
VOUT is an active high complimentary output that drives
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 Power Supply Input (VDD)
VDD may be independent of the fan’s power supply
(see Section 1.0, “Electrical Characteristics”).
2002 Microchip Technology Inc.
DS21448C-page 5
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