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PDF TB6588FG Data sheet ( Hoja de datos )
| Número de pieza | TB6588FG | |
| Descripción | 3-Phase Full-Wave PWM Driver | |
| Fabricantes | Toshiba | |
| Logotipo |  |
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TOSHIBA BiCD Integrated Circuit Silicon Monolithic
TB6588FG
TB6588FG
3-Phase Full-Wave PWM Driver for Sensorless DC Motors
The TB6588FG is a three-phase full-wave PWM driver for
sensorless brushless DC (BLDC) motors. It controls rotation speed
by changing the PWM duty cycle, based on the voltage of an
analog control input.
Features
• Sensorless drive in three-phase full-wave mode
• PWM chopper control
• Controls the PWM duty cycle, based on an analog input
(7-bit ADC)
Weight: 0.79 g (typ.)
• Output current: IOUT = 1.5 A typ. (2.5 A max)
• Power supply: VM = 7 to 42 V (50 V max)
• Overcurrent protection
• Forward and reverse rotation
• Lead angle control (0°, 7.5°, 15°, 30°)
• Overlapping commutation
• Rotation speed detecting signal
• DC excitation mode to improve starting characteristics
• Adjustable DC excitation time and forced commutation time for a startup operation
• Forced commutation frequency control: fosc/(6 × 216), fosc/(6 × 217), fosc/(6 × 218), fosc/(6 × 219)
1 2008-4-25
Free Datasheet http://www.datasheet4u.com/
1 page  
TB6588FG
Functional Description
1. Sensorless Drive Mode
Based on the analog voltage input for a startup operation, the rotor is aligned to a known position in DC
excitation mode. Then the forced commutation signal is generated to start the motor rotation. As the motor
rotates, the back-EMF occurs in each phase of the coil.
When a signal indicating the polarity of three phase voltage of the motor, including the back-EMF, is
detected at the position signal inputs (WAVEP, WAVEM), the motor driving signal is automatically switched
from the forced commutation PWM signal to the normal commutation PWM signal that is based on the
position signal input (back-EMF). Then, a BLDC motor starts running in sensorless commutation mode.
2. Startup Operation
At startup, no induced voltage is generated due to the stationary motor, and the rotor position cannot be
detected in sensorless mode. Therefore, the TB6588FG rotor is first aligned to a known position in DC
excitation mode for an appropriate period of time, and then the motor is started in forced commutation mode.
The DC excitation and forced commutation times are determined by external capacitors. These time settings
vary depending on the motor type and load, so that they should be adjusted experimentally.
VSP
VSP ≥ 1.0 (V)
VSP
SC
START
VAD (L)
TUP
VREF
TUP (typ.) = C1 × VSP/4.5 µA (s)
IP
VREF/2
(a) (b)
TFIX
(a): DC excitation time: TFIX (typ.) = 0.69 × C2 × R1 (s)
(b): Forced commutation time
GND
VSP
C1
VSP
TB6588FG
SC
IP START
R1
C2
The rotor is aligned to a known position specified in DC excitation mode for the period of (a), during which
the IP pin voltage decreases from VREF to VREF/2. The time constant for the period is determined by C2 and
R1. Then, operation mode is switched to forced commutation mode for the period of (b) as shown above. The
duty cycles for DC excitation and forced commutation modes are determined according to the SC pin voltage.
When the motor rotation frequency exceeds the forced commutation frequency specified by FST1 and FST2,
the operation mode is switched to the sensorless mode. The duty cycle for sensorless mode is determined by
VSP.
5 2008-4-25
Free Datasheet http://www.datasheet4u.com/
5 Page 
TB6588FG
12. Overcurrent Protection Circuit (Note)
The overcurrent protection circuit limits the current by turning the high-side output transistors off. The
output current is monitored as a voltage across R1. If it exceeds the rated VOC voltage (0.5 V (typ.)), the
protection functionality is enabled.
The current value that trips the overcurrent protection circuit is calculated as:
IOUT = Overcurrent detection voltage VOC/Resistor value R1
R2 and C2 used as an RC filter should be adjusted properly to prevent the malfunction of the overcurrent
protection circuit due to the PWM switching noise.
Example: When R1 = 0.33 [Ω], IOUT (typ.) = 0.5 [V] (typ.)/0.33 [Ω] ∼− 1.5 [A]
TB6588FG
VM3 VM1 VM2
200 kΩ
U
V
W
VOC = 0.5 V
OC IR3 IR1 IR2
R2
IOUT
C2 R1
Note: The overcurrent protection circuit (normally a current limiter) is not intended to provide protection against
all abnormal conditions. Therefore, the TB6588FG should exit the abnormal state immediately after the
overcurrent protection circuit is enabled.
If the device is used beyond the maximum ratings, the overcurrent protection circuit may not operate
properly, or the device may break down before the protection circuit is activated.
Also, if the overcurrent still persists after the protection circuit is activated, the device may be destroyed
due to overheating.
If the overcurrent protection circuit remains active, the timing of the position detection that is performed
synchronously with the PWM signal changes. Thus, the motor may lose synchronization. Therefore, the
overcurrent protection circuit must be configured not to operate under normal operation.
11 2008-4-25
Free Datasheet http://www.datasheet4u.com/
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet TB6588FG.PDF ] | |
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