TOSHIBA TB6548F Technical data
TOSHIBA CMOS Integrated Circuit Silicon Monolithic
T B 6 5 4 8 F
3-Phase Full-Wave PWM Sensorless Controller for Brushless DC Motors
TB6548F is a 3-phase full-wave sensorless controller for
brushless DC motors. It is capable of controlling voltage by PWM
signal input. It is capable of PWM type sensorless driving when
used conjunction with TA84005F
Features
• 3-phase full-wave sensorless drive
• PWM control (PWM signal is supplied from external sources.)
• Turn-on signal output current: 20 mA
• Built-in protection against overcurrent
• Forward/reverse modes
• Built-in lead angle control function (0, 7.5, 15 and 30 degrees)
• Built-in lap turn-on function
Weight: 0.32 g (typ.)
TB6548F
1
2001-08-28
Block Diagram
TB6548F
V
13
DD
FG_OUT
6
PWM
SEL_LAP
CW_CCW
LA0
LA1
Pin Assignment
3
8
4
1
2
PWM Control
Rotation
Instruction
Circuit
Lead Angle
Setting Circuit
Clock
Generator
Circuit
10
11
Tin
XT
Timing
Control
12
GND X
Turn-on Signal
Forming Circuit
Overcurrent
Protection
Circuit
Position
Detection
Circuit
14
17
21
15
19
22
23
24
OUT_UP
OUT_VP
OUT_WP
OUT_UN
OUT_VN
OUT_WN
OC
WAVE
NC
NC
NC
X
Tin
1
2
3
4
5
6
7
8
9
10
T
11
12
24
23
22
21
20
19
18
17
16
15
14
13
WAVE
OC
OUT_WN
OUT_WP
NC
OUT_VN
NC
OUT_VP
NC
OUT_UN
OUT_UP
V
DD
LA0
LA1
PWM
CW_CCW
FG_OUT
SEL_LAP
X
GND
2
2001-08-28
Pin Description
Pin No. Symbol I/O Description
Lead angle setting signal input pin
1 LA0 I
2 LA1 I
3 PWM I
4 CW_CCW I
5 NC Not connected
6 FG_OUT O
7 NC Not connected
8 SEL_LAP I
9 NC Not connected
10 X
11 X
12 GND Connected to GND.
13 V
14 OUT_UP O
15 OUT_UN O
16 NC Not connected
17 OUT_VP O
18 NC Not connected
19 OUT_VN O
20 NC Not connected
Tin
DD
T
• LA0 = Low, LA1 = Low: Lead angle 0 degree
• LA0 = High, LA1 = Low: Lead angle 7.5 degree
• LA0 = Low, LA1 = High: Lead angle 15 degree
• LA0 = High, LA1 = High: Lead angle 30 degree
• Built-in pull-down resistor
PWM signal input pin
• Inputs Low-active PWM signal
• Built-in pull-up resistor
• Disables input of duty-100% (Low) signal
High for 250 ns or longer is required.
Rotation direction signal input pin
• High: Reverse (U → W → V)
• Low, Open: Forward (U → V → W)
• Built-in pull-down resistor
Number of ratation detection signal output pin
• Equiralent to U-phase signal (except PWM)
Lap turn-on select pin
• Low: Lap turn-on
• High: 120 degrees turn-on
• Built-in pull-up resistor
Resonator connecting pin
• Selects starting commutation frequency.
Connected to 5-V power supply.
Starting commutation frequency f
U-phase upper turn-on signal output pin
• U-phase winding wire positive ON/OFF switching pin
• ON: Low, OFF: High
U-phase lower turn-on signal output pin
• U-phase winding wire negative ON/OFF switching pin
• ON: High, OFF: Low
V-phase upper turn-on signal output pin
• V-phase winding wire positive ON/OFF switching pin
• ON: Low, OFF: High
V-phase lower turn-on signal output pin
• V-phase winding wire negative ON/OFF switching pin
• ON: High, OFF: Low
st
TB6548F
= Resonator frequency fxt/(6 × 217)
3
2001-08-28
Pin No. Symbol I/O Description
W-phase upper turn-on signal output pin
21 OUT_WP O
22 OUT_WN O
23 OC I
24 WAVE I
• W-phase winding wire positive ON/OFF switching
• ON: Low, OFF: High
W-phase lower turn-on signal output pin
• W-phase winding wire negative ON/OFF switching pin
• ON: High, OFF: Low
Overcurrent signal input pin
• High on this pin can put constraints on the turn-on signal which is performing PWM
control.
• Built-in pull-up resistor
Positional signal input pin
• Inputs majority logic synthesis signal of three-phase pin voltage.
• Built-in pull-up resistor
Functional Description
1. Sensorless Drive
On receipt of PWM signal start instruction turn-in signal for forcible commutation (commutation
irrespective of the motor’s rotor position) is output and the motor starts to rotate. The motor’s rotation
causes induced voltage on winding wire pin for each phase.
When signals indicating positive or negative for pin voltage (including induced voltage) for each phase
are input on respective positional signal input pin, the turn-on signal for forcible commutation is
automatically switched to turn-on signal for positional signal (induced voltage).
Thereafter turn-on signal is formed according to the induced voltage contained in the pin voltage so as to
drive the brushless DC motor.
2. Starting commutation frequency
The forcible commutation frequency at the time of start is determined by the resonator’s frequency and
the number of counter bit (within the IC).
Starting commutation frequency f
The forcible commutation frequency at the time of start can be adjusted using inertia of the motor and
load.
• The forcible commutation frequency should be set higher as the number of magnetic poles increases.
• The forcible commutation frequency should be set lower as the inertia of the load increases.
3. PWM Control
PWM signal can be reflected in turn-on signal by supplying PWM signal from external sources.
The frequency of the PWM signal shoud be set adequately high with regard to the electrical frequency of
the motor and in accordance to the switching characteristics of the drive circuit.
Because positional detection is performed in synchronization with the falling edges of PWM signal,
positional detection cannot be performed with 0% duty or 100% duty.
(resonator pin and counter bit select pin)
= Resonator frequency fxt/(6 × 2
st
pin
(bit + 3)
TB6548F
) bit = 14
Duty (max)
250 ns
Duty (min)
250 ns
The voltage applied to the motor is duty 100% because of the storage time of the drive circuit even if the
duty is 99%.
4
2001-08-28
Loading...