MTD6501C 데이터 시트보기 (PDF) - Microchip Technology
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MTD6501C Datasheet PDF : 24 Pages
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3.0 FUNCTIONAL DESCRIPTION
The MTD6501C/D/G devices generate a full-wave sig-
nal to drive a 3-phase sensorless BLDC motor. High
efficiency and low-power consumption are achieved
due to DMOS transistors and synchronous rectification
drive type. The current carrying order of the output is as
follows: OUT1 OUT2 OUT3.
3.1 Speed Control
The rotational speed of the motor can be controlled
either through the PWM digital input signal or by acting
directly on the power supply (VCC). When the PWM
signal is “High” (or left open) the motor rotates at full
speed. When the PWM signal is “Low”, the motor is
stopped (and the IC outputs are set to high-
impedance). By changing the PWM duty cycle, the
speed can be adjusted. Notice that the PWM frequency
has no special meaning for the motor speed and is
asynchronous with the activation of the output
transistors. Thus, the user has maximum freedom to
choose the PWM system frequency within a wide range
(from 20 Hz to 100 kHz), while the output transistor
activation always occurs at a fixed rate, which is
outside of the range of audible frequencies. The
MTD6501C and MTD6501D typical output frequency is
20 kHz. The MTD6501G output frequency is 23 kHz.
3.2 Frequency Generator Function
The Frequency Generator output is a “Hall-sensor
equivalent” digital output, giving information to an
external controller about the speed and phase of the
motor. The FG pin is an open drain output, connecting
to a logical voltage level through an external pull-up
resistor. When a lock (or out-of-sync) situation is
detected by the driver, this output is set to high-imped-
ance until the motor is restarted. Leave the pin open
when not used. The FG signal can be used to compute
the motor speed in rotations per minute (RPM). Typi-
cally, for a four pole BLDC fan, the speed in RPMs is 30
FG frequency (Hz).
3.3 Lockup Protection and Automatic
Restart
If the motor is stopped (blocked) or if it loses
synchronization with the driver, a lock-up protection
circuit detects this situation and disables the driver (by
setting its outputs to high-impedance) in order to
prevent the motor coil from burnout. After a “waiting
time” (TWAIT), the lock-up protection is released and
normal operation resumes for a given time (TRUN). In
case the motor is still blocked, a new period of waiting
time is started. TWAIT and TRUN timings are fixed
internally, so that no external capacitor is needed.
MTD6501C/D/G
3.4 Overcurrent Protection and Short
Circuit Detection
The motor peak current is limited by the driver to a fixed
value (defined internally), thus limiting the maximum
power dissipation in the coils. The detection of a short-
circuit situation immediately sets the driver outputs to
high-impedance, in order to avoid permanent damage
to the IC.
3.5 Thermal Shutdown
The MTD6501C/D/G have a thermal protection
function which detects when the die temperature
exceeds TSD = +170°C. When this temperature is
reached, the circuit enters Thermal Shutdown mode
and the outputs OUT1, OUT2 and OUT3 are disabled
(high-impedance), avoiding IC destruction and allowing
the circuit to cool down. Once the junction temperature
(TSD) has dropped below +145°C, the normal operation
resumes (thermal detection circuit has +25°C
hysteresis function).
Thermal Shutdown
Normal operation
+145°C
+170°C
TSD
FIGURE 3-1:
Hysteresis.
Thermal Protection
3.6 Internal Voltage Regulator
VDD voltage is generated internally and is used to
supply internal logical blocks. The VDD pin is used to
connect an external decoupling capacitor (1 µF or
higher). Notice that this pin is for IC internal use and is
not designed to supply DC current to external blocks.
2010-2012 Microchip Technology Inc.
DS22263B-page 9
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