TC647B Microchip Technology Inc., TC647B Datasheet - Page 10

• Manufacturer Part Number: TC647B
• Description: Pwm Fan Speed Controllers With Minimum Fan Speed, Fan Restart And Fansense Technology For Fault Detection
• Manufacturer: Microchip Technology Inc.

TC642B/TC647B
3.0
The description of the pins are given in Table 3-1.
TABLE 3-1:
3.1
The thermistor network (or other temperature sensor)
connects to V
ical) on this pin drives an active duty cycle of 0% to
100% on the V
3.2
C
timing capacitor. The recommended value for the C
capacitor is 1.0 µF for 30 Hz PWM operation.
3.3
An external resistor divider connected to V
minimum fan speed by fixing the minimum PWM duty
cycle (1.20V to 2.60V = 0% to 100%, typical). The
TC642B and TC647B devices enter shutdown mode
when 0
output is inactive and supply current falls to 30 µA
(typical).
3.4
Pulses are detected at SENSE as fan rotation chops
the current through a sense resistor. The absence of
pulses indicates a fan fault condition.
DS21756B-page 10
F
is the positive terminal for the PWM ramp generator
Pin
1
2
3
4
5
6
7
8
PIN FUNCTIONS
Analog Input (V
Analog Output (C
Analog Input (V
Analog Input (SENSE)
V
MIN
SENSE
FAULT
Name
V
IN
GND
V
V
V
C
OUT
OUT
MIN
. A voltage range of 1.20V to 2.60V (typ-
DD
IN
F
V
PIN FUNCTION TABLE
SHDN
pin.
Analog Input
Analog Output
Analog Input
Ground
Analog Input
Digital (Open-Drain) Output
Digital Output
Power Supply Input
. During shutdown, the FAULT
IN
MIN
)
F
Function
)
)
MIN
sets the
F
3.5
The FAULT line goes low to indicate a fault condition.
When FAULT goes low due to a fan fault, the output will
remain low until the fan fault condition has been
removed (16 pulses have been detected at the SENSE
pin in a 32/f period). For the TC642B device, the FAULT
output will also be asserted when the V
reaches the V
an over-temperature/100% fan speed indication
3.6
V
drives the base of an external NPN transistor (via an
appropriate base resistor) or the gate of an N-channel
MOSFET. This output has asymmetrical drive. During a
fan fault condition, the V
3.7
The V
device. This bias supply voltage may be independent of
the fan power supply.
OUT
DD
is an active-high complimentary output and
Digital (Open-Drain) Output
(FAULT)
Digital Output (V
Power Supply Input (V
pin with respect to GND provides power to the
OTF
treshold of 2.62V (typical). This gives
OUT
2003 Microchip Technology Inc.
output is continuously on.
OUT
)
DD
)
IN
voltage
.