TB6556FG_12 datasheet(11/22 Pages) TOSHIBA | 3-Phase Full-Wave Sine-Wave PWM Brushless Motor Controller

11 / 22 page

TB6556FG

2012-10-22

Functional Description

Basic operation

The motor is driven by the square-wave turn-on signal based on a positional signal. When the positional

signal reaches frequency f = 5 Hz or higher, the rotor position is estimated according to the positional

signal and a modulation wave is generated. The modulation wave and the triangular wave are compared;

then the sine-wave PWM signal is generated and the motor is driven.

From start to 5 Hz: When driven by square wave (120° turn-on) f = fOSC / (212  32  6)

5 Hz or higher: When driven by sine-wave PWM (180° turn-on);

when fOSC = 4 MHz, approx. 5 Hz

Select drive function

This function can select drive mode.

SS pin

HIGH or OPEN = Sine-wave PWM drive (180° turn-on mode)

LOW = Square-wave drive (120° turn-on mode)

Note: If the position sensing signal is f = 5 Hz or lower, the driver is 120° turn-on mode even when SS =

HIGH.

Ve voltage command signal function and function to stabilize bootstrap voltage

(1)

When the voltage command signal is input at Ve ≤ 1.0 V:

Turns off output (gate protection)

(2)

When the voltage command signal is input at 1.0 V

 Ve ≤ 2.1 V:

Turns on the lower transistor at the regular (carrier) cycle. (ON duty is approx. 8%.)

(3)

When the voltage command signal is input at Ve  2.1 V:

During sin-wave drive, outputs drive signal as it is. During square-drive, forcibly turns on the lower

transistor at regular (carrier) cycle. (ON duty is approx. 8%)

Note: At startup, turn the lower transistor on for a fixed time with 1.0 V

 Ve ≤ 2.1 V to charge the

upper transistor gate power supply.

Dead time function: upper/lower transistor output off-time

When the motor is driven by sine-wave PWM, dead time is digitally generated in the IC to prevent a

short circuit caused by the simultaneous turning on of upper and lower external power devices. When a

square wave is generated in full-duty cycle mode, the dead time function is turned on to prevent a short

circuit.

Td Pin

Internal Counter

TOFF

HIGH or OPEN

8/fOSC

1.9

μs

LOW

16/fOSC

3.8

μs

TOFF values above are obtained when fOSC = 4.19 MHz.

fOSC = reference clock (ceramic oscillation)

(1)

(2)

(3)

100%

2.1 V

1.0 V

5.4 V

PWM Duty

TB6556FG Datasheet(PDF) 11 Page - Toshiba Semiconductor

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