TC643VUA Microchip Technology, TC643VUA Datasheet - Page 4

• Manufacturer Part Number: TC643VUA
• Description: IC FAN/MOTOR DRIVER 8-MSOP
• Manufacturer: Microchip Technology

Specifications of TC643VUA

• Applications: DC Motor Driver, Brushless (BLDC)
• Number Of Outputs: 1
• Voltage - Load: 15V
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Contains lead / Request inventory verification
• Current - Output: -
• Other names: 158-1035; 158-1035

TC643-1 9/29/97
DETAILED DESCRIPTION
and analog signal-processing circuitry for fan management
into a single, easy-to-use device. Only three logic signals
interface the TC643 to its host. A number of value-added
features can now be implemented by the system designer
with minimal impact on cost, space, and design time. The
advantages of a fan management system built around the
TC643 may include:
Power Driver
logic input. The on-chip NPN power transistor is switched
on when this input is high. The output features a high
efficiency NPN power transistor ( low V
operation. This permits driving even large motors with a DIP
or SOIC packaged device. Normally, this input is driven with
a digital PWM waveform to control fan speed. The FAN
terminal will stand off 15V. The ground return for the power
driver, GND
return, GND, and the motor’s power supply can be indepen-
dent of the IC’s. See the Electrical Characteristics section
for more details.
ILMT
limited to a preset value, I
open collector output will go low. I
I
motor, or other fault. Typically this output is connected to an
interrupt input of the host microcontroller. ILMT may go
active momentarily during motor start-up. The digital control
circuitry should ignore this indication until the motor has time
to start. See the Electrical Characteristics and Applications
sections for more details.
RPM
each pole of the fan is energized. This causes brief interrup-
TC643
LIMIT
The TC643 is the first IC which integrates all the power
(1) High Integration: higher reliability, lower cost, less
(2) PWM Speed Control: better efficiency, reduced
(3) Fan Feedback and Diagnostics: system-level fault-
The DRV input is a standard CMOS/TTL compatible
The motor current through the TC643, I
During normal fan operation, commutation occurs as
. This serves as an indication of a stalled or shorted
design effort.
operating temperatures, wide speed-control range,
less acoustic noise, longer fan life, speed control
of low-voltage fans without stalling.
tolerance, device-level fault protection, intelligent
fault prediction, real-time fan performance charac-
terization and trending.
FAN
, is separate from the IC’s power supply
LIMIT
. If I
FAN
FAN
exceeds I
CE(SAT)
will be clamped at
FAN
, is internally
) for cooler
LIMIT
, this
4
tions in the fan current (See Figure 1). The TC643 detects
these perturbations in fan current by monitoring the current
through the on-chip drive transistor. Internal signal condi-
tioning circuitry derives a pulse-train representing the fan-
pole crossings. RPM outputs a high-going pulse each time
a fan pole-crossing is detected. See the Electrical Charac-
teristics section for detailed timing information. The host
microcontroller or digital control logic can derive the motor
rpm by timing the period of the waveform present on RPM.
If commutation occurs while the power driver is off, a pulse
will not be detected. A careful study of the motor rpm range
and PWM frequency of interest is called for when designing
with the TC643. See the Applications section for more
details.
C
ground serves as part of the signal conditioning circuitry
which derives the RPM output. It is effectively part of a
differentiator designed to sense the commutation of the fan.
These commutation pulses are translated to logic-level and
squared-up to produce the RPM signal. The characteristics
of this capacitor are not particularly critical. A 0.002 F, 5.0V
ceramic type is suggested.
APPLICATIONS INFORMATION
This section provides simple methodologies and guidelines
to deal with each one. With reasonable care and thoughtful-
ness, it is a straightforward procedure to design a complete
fan management system that is efficient, reliable, and “fea-
ture-rich”.
EXT
INTEGRATED FAN / MOTOR DRIVER
A 0.002 F (typical) capacitor between this pin and
Designing with the TC643 involves a number of issues.
Applying the TC643 generally involves . . .
(1) Matching a fan (or motor) with the desired perfor -
(2) Selecting a PWM frequency and duty-cycle range
(3) Architecting the microcontroller hardware and soft-
mance to the TC643.
ware (or other control scheme) to drive the TC643
and take full advantage of its fan management
capabilities.
and considering its impact on RPM determination.
© 2001 Microchip Technology Inc.
DS21445A