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PDF MTD6508 Data sheet ( Hoja de datos )
| Número de pieza | MTD6508 | |
| Descripción | 3-Phase Sinusoidal Sensorless Brushless DC Fan Motor Driver | |
| Fabricantes | Microchip | |
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MTD6508
3-Phase Sinusoidal Sensorless Brushless DC Fan Motor Driver
Features
• 180° Sinusoidal Drive for High Efficiency and Low
Acoustic Noise
• Position Sensorless BLDC Drivers
(no Hall Effect Sensor required)
• Integrated Power Transistors
• Supports 2V to 5.5V Power Supplies
• Variable Programming Resistor (RPROG) Setting
to fit Motor Constant (KM) Range from 3.25 mV/
Hz to 52 mV/Hz
• Speed Control through Power Supply Modulation
(PSM) and/or Pulse-Width Modulation (PWM)
• Built-in Frequency Generator: FG, FG/3 Output
Signal (FG/2 and FG/6 Option are available upon
request)
• Output PWM Slew Rate Control Programmable
with an External Resistor for Start-up
(Adjustable version)
• Phase Target Selection for Regulation
(Adjustable Version)
• Start-up Strength Selection (Adjustable Version)
• Start-up Output Current Controlled by PWM
• Output Current Soft Start
• Built-in Lock-up Protection and Automatic
Recovery Circuit
• Built-in Overcurrent Limitation
• Built-in Thermal Shutdown Protection
• Built-in Overvoltage Protection
• Low Minimal Start-up Speed for Low-Speed
Operation
• Packages:
- 10-Lead 3 mm x 3 mm x 0.5 mm UDFN
- 16-Lead 4 mm x 4 mm x 0.5 mm UQFN
(Adjustable version)
Applications
• Notebook CPU Cooling Fans
• 5V 3-Phase BLDC Motors
Description
The MTD6508 device is a 3-phase, full-wave
sensorless driver for brushless DC (BLDC) motors. It
features a 180° sinusoidal drive, high torque output and
silent drive. With adaptive features, parameters and a
wide range of power supplies (2V to 5.5V), the
MTD6508 is intended to cover a broad range of motor
characteristics while requiring minimum external
components. Speed control can be achieved through
either power supply modulation (PSM) or pulse-width
modulation (PWM).
Compact packaging and a minimal bill of materials
make the MTD6508 device extremely cost-efficient in
fan applications. For example, the CPU cooling fans in
notebook computers require designs that provide low
acoustic noise, low mechanical vibration and are highly
efficient. The frequency generator (FG) output enables
precision speed control in closed-loop applications.
The MTD6508 device includes Lock-up Protection
mode to turn off the output current when the motor is in
a lock condition, with an automatic recovery feature to
restart the fan when the lock condition is removed.
Motor overcurrent limitation and thermal shutdown
protection are included for safety-enhanced operations.
The MTD6508 is available in compact, thermally-
enhanced, 10-Lead 3 mm x 3 mm x 0.5 mm UDFN
packages and 16-Lead 4 mm x 4 mm x 0.5 mm
UQFN packages.
2015 Microchip Technology Inc.
DS20005359A-page 1
1 page  
MTD6508
1.0 ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings†
Power Supply Voltage (VDD_MAX) ...................... -0.7 to +7.0V
Maximum Output Voltage (VOUT_MAX) ............... -0.7 to +7.0V
Maximum Output Current (IOUT_MAX)(1) ....................1000 mA
FG Maximum Output Voltage (VFG_MAX) ........... -0.7 to +7.0V
FG Maximum Output Current (IFG_MAX) ......................5.0 mA
VBIAS Maximum Voltage (VBIAS_MAX) ................ -0.7 to +4.0V
PWM Maximum Voltage (VPWM_MAX) ................ -0.7 to +7.0V
Allowable Power Dissipation (PD_MAX)(2)........................1.5W
Maximum Junction Temperature (TJ) .......................... +150°C
ESD protection on all pins 2 kV
† Notice: Stresses above those listed under “Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only, and functional operation of
the device at those or any other conditions above those
indicated in the operational listings of this specification
is not implied. Exposure to maximum rating conditions
for extended periods may affect device reliability.
Note 1: IOUT is also internally limited, according
to the limits defined in the Electrical
Characteristics table.
2: Reference Printed Circuit Board (PCB)
according to JEDEC standard EIA/JESD
51-9.
ELECTRICAL CHARACTERISTICS
Electrical Specifications: Unless otherwise specified, all limits are established for VDD = 2.0V to 5.5V, TA = +25°C
Parameters
Sym.
Min.
Typ.
Max.
Units
Conditions
Power Supply Voltage
Power Supply Current
Standby Current
VDD
IVDD
IVDD_STB
2
—
—
— 5.5 V
5 10 mA VDD = 5V
15 25 µA PWM = 0V, VDD = 5V
(Standby mode)
OUTX High Resistance
RON(H)
—
0.75 —
Ω IOUT = 0.5A, VDD = 5V
OUTX Low Resistance
RON(L)
—
0.75 —
Ω IOUT = 0.5A, VDD = 5V
OUTX Total Resistance
RON(H+L)
—
1.5 — Ω IOUT = 0.5A, VDD = 5V
VBIAS Internal
Supply Voltage
VBIAS
— 3—
—
VDD – 0.2
—
V VDD = 3.2V to 5.5V
V VDD < 3.2V
PWM Input Frequency
fPWM
1
— 100 kHz
PWM Input H Level
VPWM_H 0.55 VDD
—
VDD
V VDD 4.5V
PWM Input L Level
VPWM_L
0
— 0.2 VDD V VDD 4.5V
FG3_SEL Input H Level
VFG3_SEL_H VBIAS – 0.5
—
VBIAS
V VDD 4.5V
FG3_SEL Input L Level
VFG3_SEL_L
0
— 0.2 VDD V VDD 4.5V
FG Output Pin Low-Level
Voltage
VOL_FG
—
— 0.25 V IFG = -1 mA
FG Output Pin Leakage
Current
ILH_FG
-10
— 10 µA VFG = 5.5V
Lock Protection
Operating Time
TRUN
—
0.5 1
s
Lock Protection Waiting Time
Overcurrent Protection
TWAIT
IOC_MOT
5
—
5.5 6
s Note 1
750 — mA Note 2
Note 1: Related to the internal oscillator frequency (see Figure 2-1)
2: 750 mA is the standard option for MTD6508. Additional overcurrent protection levels are available upon
request. Please contact factory for different overcurrent protection values.
2015 Microchip Technology Inc.
DS20005359A-page 5
5 Page 
4.0 FUNCTIONAL DESCRIPTION
The MTD6508 generates a full-wave signal to drive a
3-phase BLDC motor. High efficiency and low power
consumption are achieved due to CMOS transistors
and a synchronous rectification drive type.
4.1 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 (VDD). When the PWM
signal is High, the motor rotates at full speed. When the
PWM signal is low, the IC outputs are set to high-
impedance and the motor is stopped.
By changing the PWM duty cycle, the speed can be
adjusted. Thus, the user has maximum freedom to
choose the PWM system frequency within a wide range
(from 1 kHz to 100 kHz).
The PWM pin should not be floating. It can be connected
to an external pull-up resistor connected to VDD.
When the PWM duty cycle is below 5%, MTD6508
directly stops the drive (output High Z) and will restart
only if the PWM duty cycle is above 5%. If MTD6508 is
not in standby mode (PWM duty cycle = 0%), it will not
restart unless a “waiting time” (TWAIT) has been spent
in order to allow the fan to break enough before the
next start-up. TWAIT begins as soon as the PWM duty
cycle falls below 5%.
The output transistor activation always occurs at a fixed
rate of 30 kHz, which is outside the range of audible
frequencies.
Note 1: The PWM frequency has no direct effect
on the motor speed, and is asynchronous
with the activation of the output transistors.
4.2 Frequency Generator Function
The Frequency Generator output (FG) is a Hall effect
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 an out-of-sync situation is
detected by the driver, this output is set to high-
impedance until the motor is restarted. The pin should
be left open when it is not used.
EQUATION 4-1:
F-----G-P---------7-S--2---0-- = Rotor speed RPM
Where:
P = Total number of poles in the motor
S = Total number of slots in the motor
MTD6508
If the FG3_SEL pin is enabled, the rotor speed rotation
per minute (RPM) has to be multiplied by three, because
the FG signal frequency will be divided by three.
OUT1
FG
FG/3
FIGURE 4-1:
FG and FG/3 Waveform.
4.3 Lock-Up Protection and Automatic
Restart
If the motor is blocked and cannot rotate freely, a lock-
up protection circuit detects it and disables the driver by
setting its outputs to high-impedance 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). If 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 required.
4.4 Overcurrent Protection
The motor peak current is limited by the driver to
750 mA (standard value), thus limiting the maximum
power dissipation in the coils.
4.5 Thermal Shutdown
The MTD6508 has a thermal protection function which
detects when the die temperature exceeds
TJ = +170°C. When this temperature is reached, the
circuit enters the Thermal Shutdown mode and the
outputs OUT1, OUT2 and OUT3 are disabled (high-
impedance): avoiding the IC destruction and allowing
the circuit to cool down. When the junction temperature
(TJ) drops below +145°C, normal operation resumes.
The thermal detection circuit has +25°C hysteresis.
Thermal shutdown
Normal
operation
+145°
FIGURE 4-2:
Hysteresis.
+170°
TJ
Thermal Protection
2015 Microchip Technology Inc.
DS20005359A-page 11
11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet MTD6508.PDF ] | |
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