TC648EUA713 Microchip Technology, TC648EUA713 Datasheet - Page 6

• Manufacturer Part Number: TC648EUA713
• Description: IC PWM FAN SPEED CONTRLR 8-MSOP
• Manufacturer: Microchip Technology
• Type: Controller - PWM Fanr

Specifications of TC648EUA713

• Applications: Fan Controller, Brushless (BLDC)
• Number Of Outputs: 1
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Product: Fan / Motor Controllers / Drivers
• Operating Supply Voltage: 3 V to 5.5 V
• Supply Current: 400 uA
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Load: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

TC648
3.0
3.1
The PWM circuit consists of a ramp generator and
threshold detector. The frequency of the PWM is
determined by the value of the capacitor connected to
the C
most applications (C
time base for the Start-up Timer (see Section 3.3,
“Start-up Timer”). The PWM voltage control range is
1.25V to 2.65V (typical) for 0% to 100% output duty
cycle.
3.2
The V
or MOSFET as the low side power switching element in
the system. Various examples of driver circuits will be
shown throughout this data sheet. This output has
asymmetric complementary drive and is optimized for
driving NPN transistors or N-channel MOSFETs. Since
the system relies on PWM rather than linear control,
the power dissipation in the power switch is kept to a
minimum. Generally, very small devices (TO-92 or SOT
packages) will suffice.
3.3
To ensure reliable fan start-up, the Start-up Timer turns
the V
the fan is started from the off state. This occurs at
power-up and when coming out of shutdown or auto-
shutdown mode. If the PWM frequency is 30 Hz
(C
approximately one second.
3.4
OTF is asserted when the PWM control voltage applied
to V
duty cycle (see Section 1.0, “Electrical Characteris-
tics”). This indicates that the fan is at maximum drive,
and the potential exists for system overheating. Either
heat dissipation in the system has gone beyond the
cooling system’s design limits, or some subtle fault
exists (such as fan bearing failure or an airflow obstruc-
tion). This output may be treated as a “System Over-
heat” warning and used to trigger system shutdown or
some other corrective action. OTF will become inactive
when V
DS21448C-page 6
F
IN
= 1 µF), the resulting start-up time will be
OUT
F
OUT
becomes greater than that needed to drive 100%
pin. A frequency of 30 Hz is recommended for
IN
DETAILED DESCRIPTION
PWM
V
Start-Up Timer
Over-Temperature Fault (OTF)
Output
output on for 32 cycles of the PWM whenever
< V
pin is designed to drive a low cost transistor
OUT
OTF
Output
.
F
= 1 µF). The PWM is also the
3.5
If the voltage on V
V
mode). The TC648 exits auto-shutdown mode when
the voltage on V
V
(see Figure 3-1)). The Start-up Timer is triggered and
normal operation is resumed upon exiting auto-shut-
down mode. The V
shutdown mode is not used.
3.6
If an unconditional shutdown and/or device reset is
desired, the TC648 may be placed in shutdown mode
by forcing V
Figure 3-1). In this mode, all functions cease and the
OTF output is unconditionally inactive. The TC648
should not be shut down unless all heat producing
activity in the system is at a negligible level. The TC648
exits shutdown mode when V
V
Entering shutdown mode also performs a complete
device reset. Shutdown mode resets the TC648 into its
power-up state. OTF is unconditionally inactive in shut-
down mode. Upon exiting shutdown mode (V
V
operation will resume, assuming V
If V
shutdown mode, the fan will not be restarted. To ensure
that a complete reset takes place, the user’s circuitry
must ensure that V
is released from shutdown mode. A recommended
algorithm for management of the TC648 by a host
microcontroller or other external circuitry is given in
Section 5.0, “Typical Applications”. A small amount of
hysteresis, typically one percent of V
V
old. The levels specified for V
Section 1.0, “Electrical Characteristics”, include this
hysteresis plus adequate margin to account for normal
variations in the absolute value of the threshold and
hysteresis.
Note: If V
mode, the fan will not restart as it will be in auto-shut-
down mode.
CAUTION: Shutdown mode is unconditional. That is,
the fan will remain off as long as the V
held low or V
AS
AS
REL
REL
DD
, the fan is automatically shut off (auto-shutdown
IN
by V
= 5.0V), is designed into the V
, the release voltage.
), the Start-up Timer will be triggered and normal
is not greater than (V
Auto-Shutdown Mode
Shutdown Mode (Reset)
HAS
IN
IN
< V
IN
(the auto-shutdown hysteresis voltage
to a logic low (i.e., V
IN
< V
AS
IN
becomes higher than the voltage on
AS
IN
AS
becomes less than the voltage on
when the device exits shutdown
input should be grounded if auto-
> (V
+ V
AS
2002 Microchip Technology Inc.
HAS
+ V
AS
IN
.
becomes greater than
+ V
HAS
SHDN
IN
SHDN
HAS
) when the device
IN
> V
IN
< V
) upon exiting
DD
AS
and V
/V
pin is being
REL
SHDN
+ V
(50 mV at
HAS
thresh-
REL
) (see
IN
in
>