TC642BEPA Microchip Technology, TC642BEPA Datasheet - Page 14

• Manufacturer Part Number: TC642BEPA
• Description: IC PWM FAN SPEED CTRLR 8-DIP
• Manufacturer: Microchip Technology
• Type: PWM Fan Speed Controllerr

Specifications of TC642BEPA

• Applications: Fan Controller, Brushless (BLDC)
• Number Of Outputs: 1
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Motor Type: PWM
• No. Of Outputs: 1
• Output Current: 5mA
• Output Voltage: 4.4V
• Supply Voltage Range: 3V To 5.5V
• Driver Case Style: DIP
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Product: Fan / Motor Controllers / Drivers
• Operating Supply Voltage: 6 V
• Supply Current: 400 uA
• Mounting Style: Through Hole
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Load: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

TC642B/TC647B
FIGURE 4-5:
4.7
The FAULT output is an open-drain, active-low output.
For the TC642B and TC647B devices, the FAULT out-
put indicates when a fan fault condition has occurred.
For the TC642B device, the FAULT output also indi-
cates when an over-temperature (OTF) condition has
occurred.
For the TC642B device, an over-temperature condition
is indicated (FAULT output is pulled low) when the V
input reaches the V
threshold voltage is typically 20 mV higher than the
V
indicates that maximum cooling capacity has been
reached (the fan is at full speed) and that an overheat-
ing situation can occur. When the voltage at the V
input falls below the V
teresis value (V
the high-state (a pull-up resistor is needed on the
FAULT output).
A fan fault condition is indicated when fan current
pulses are no longer detected at the SENSE pin.
Pulses at the SENSE pin indicate that the fan is
spinning and conducting current.
If pulses are not detected at the SENSE pin for 32 PWM
cycles, the 3-cycle diagnostic timer is fired. This means
that the V
are detected in this 3-cycle period, then normal PWM
operation is resumed and no fan fault is indicated. If no
pulses are detected in the 3-cycle period, the start-up
timer is activated and the V
32 PWM cycles. If pulses are detected during this time-
frame, normal PWM operation is resumed. If no pulses
are detected during this time frame, a fan fault condition
exists and the FAULT output is pulled low.
DS21756B-page 14
CMAX
threshold and has 80 mV of hysteresis). This
Clamp Diode
FAULT Output
OUT
V
output is high for 3 PWM cycles. If pulses
OUT
Q
OTF-HYS
1
: N-Channel MOSFET
OTF
OTF
Clamp Diode for Fan.
), the FAULT output returns to
threshold voltage (the V
threshold voltage by the hys-
OUT
output is driven high for
FAN
GND
R
Q
SENSE
1
OTF
IN
IN
During a fan fault condition, the FAULT output will
remain low until the fault condition has been removed.
During this time, the V
uously to attempt to restart the fan, and the SENSE pin
is monitored for fan pulses. If a minimum of 16 pulses
are detected at the SENSE input over a 32 cycle time
period (one second for C
dition no longer exists. The FAULT output is then
released and the V
operation, as dictated by the V
If the V
ing a fan fault condition, the FAULT output will be
released and the V
(V
the V
normal start-up routine.
If, during a fan fault condition, the voltage at the V
drops below the V
TC647B device will continue to hold the FAULT line low
and drive the V
fault condition is then removed, the FAULT output will
be released and the V
duty cycle that is being commanded by the V
The sink current capability of the FAULT output is listed
in the “Electrical Characteristics” table of Section 1.0.
4.8
The SENSE input is an analog input used to monitor
the fan’s operation. It does this by sensing fan current
pulses, which represent fan rotation. When a fan
rotates, commutation of the fan current occurs as the
fan poles pass the armatures of the motor. The commu-
tation of the fan current makes the current waveshape
appear as pulses. There are two typical current wave-
forms of brushless DC fan motors. These are shown in
Figures 4-6 and 4-7.
FIGURE 4-6:
And Positive Commutation Current.
OUT
REL
= 0V). If the V
MIN
Sensing Fan Operation (SENSE)
threshold, the device will go through the
voltage is pulled below the V
OUT
OUT
output to 100% duty cycle. If the fan
MIN
MIN
OUT
OUT
OUT
Fan Current With DC Offset
output returns to normal PWM
voltage then increases above
F
voltage level, the TC642B/
2003 Microchip Technology Inc.
output is driven high contin-
= 1.0 F), the fan fault con-
output will be driven to the
output will be shutdown
IN
and V
MIN
SHDN
inputs.
MIN
level dur-
input.
IN
pin