tb6551fag TOSHIBA Semiconductor CORPORATION, tb6551fag Datasheet - Page 9

• Manufacturer Part Number: tb6551fag
• Description: 3-phase Full-wave Sine-wave Pwm Brushless Motor Controller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Functional Description
Basic operation
Function to stabilize bootstrap voltage
Dead time function: upper/lower transistor output off-time
Correcting lead angle
Setting carrier frequency
Switching the output of turn-on signal
the positional signal reaches number of rotations f = 5 Hz or higher, the rotor position is inferred from the
positional signal and a modulation wave is generated. The modulation wave and the triangular wave are
compared; the sine-wave PWM signal is then generated and the motor is driven.
(1)
(2)
short circuit caused by the simultaneous turning on of upper and lower external power devices.
a short circuit.
voltage.
square wave.)
On start-up, the motor is driven by the square-wave turn-on signal based on a positional signal. When
When the motor is driven by a sine-wave PWM, dead time is generated digitally in the IC to prevent any
When a square wave is generated in full duty cycle mode, the dead time function is turned on to prevent
The lead angle can be corrected in the turn-on signal range from 0 to 58° in relation to the induced
Analog input from LA pin (0 V to 5 V divided by 32):
This feature sets the triangular wave cycle (carrier cycle) necessary for generating the PWM signal.
(The triangular wave is used for forcibly turning on the lower transistor when the motor is driven by
This function switches the output of the turn-on signal between high and low.
Pin OS:
High or Open
From start to 5 Hz: When driven by square wave (120° turn-on) f = f
5 Hz or higher: When driven by sine-wave PWM (180° turn-on) When f
T
f
0 V = 0°
5 V = 58° (when more than 5 V is input, 58°)
Carrier cycle = f
High = active high
Low = active low
osc
When voltage instruction is input at V
The lower transistor is turned on at the regular (carrier) cycle. (On duty is approx. 8%.)
When voltage instruction is input at V
(On duty is approx. 8%.)
Note: At startup, to charge the upper transistor gate power supply, turn the lower transistor on for a fixed
OFF
Td Pin
During sine-wave drive, the drive signal is output as it is.
During square-wave drive, the lower transistor is forcibly turned on at the regular (carrier) cycle.
Low
= reference clock (ceramic oscillation)
values above are obtained when f
time with V
osc
e
Internal Counter
/ 252 (Hz)
≤ 0.2 V.
11/f
16/f
osc
osc
osc
e
e
≤ 0.2 V:
> 0.2 V:
= 4.19 MHz.
2.6 μs
3.8 μs
T
9
OFF
f
osc
= Reference clock (ceramic oscillation)
osc
/(2
osc
12
= 4 MHz, approx. 5 Hz
× 32 × 6)
TB6551FG/FAG
2008-12-24