TB6575FNG
TOSHIBA CMOS Integrated Circuit
Silicon Monolithic
TB6575FNG
PWM Sensorless Controller for 3-Phase Full-Wave BLDC Motors
The TB6575FNG provides sensorless commutation and PWM
current control for 3-phase full-wave BLDC motors. It controls
rotation speed by changing a PWM duty cycle by analog voltage.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
3-phase full-wave sensorless drive
PWM chopper drive
PWM duty cycle control by analog input
20-mA current sink capability on PWM output pins
Overcurrent protection
Forward/reverse rotation
Lead angle control (7.5° and 15°)
Overlap commutation
Rotation speed sensing signal
DC excitation mode to improve startup characteristic
DC excitation time and forced commutation time for startup operation can be changed.
Forced commutation frequency can be selected. (f
XT
/(6 × 2
16
), f
XT
/(6 × 2
17
), f
XT
/(6 × 2
18
) )
Output polarity switching (P-channel + N-channel, N-channel + N-channel)
Weight: 0.14 g (typ.)
The following conditions apply to solderability:
*Solderability
1. Use of Sn-37Pb solder bath
*solder bath temperature = 230ºC
*dipping time = 5 seconds
*number of times = once
*use of R-type flux
2. Use of Sn-3.0Ag-0.5Cu solder bath
*solder bath temperature = 245ºC
*dipping time = 5 seconds
*number of times = once
*use of R-type flux
1
2006-3-6
TB6575FNG
Block Diagram
Duty
19
V
DD
21
OS FG_OUT
3
7
V
SP
5
Startup time
setting
6-bit AD
converter
PWM
control
13 OUT_UP
15 OUT_VP
SC 2
START 8
IP 9
F
ST
24
DC excitation
control circuit
Forced
commutation
frequency setting
Maximum
commutation
frequency setting
Lead angle
setting
Overcurrent
protection
22 OC
PWM
generator
17 OUT_WP
14 OUT_UN
16 OUT_VN
Timing
control
18 OUT_WN
F
MAX
4
LA 12
CW_CCW 6
SEL_LAP 20
Clock
generation
10
X
Tout
11
X
Tin
1
GND
Position
recognition
23 WAVE
Pin Assignment
GND
SC
OS
F
MAX
V
SP
CW_CCW
FG_OUT
START
IP
X
Tout
X
Tin
LA
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
F
ST
WAVE
OC
V
DD
SEL_LAP
Duty
OUT_WN
OUT_WP
OUT_VN
OUT_VP
OUT_UN
OUT_UP
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2006-3-6
TB6575FNG
Pin Description
Pin No.
1
2
Symbol
GND
SC
I/O
⎯
I
Ground pin
Connection pin for a capacitor to set a startup commutation time and duty cycle ramp-up
time
Select the polarity of transistors.
High or open : High-side transistor
=
P-channel (active low)
Low-side transistor
=
N-channel (active low)
Low
: High-side transistor
=
N-channel (active low)
Low-side transistor
=
N-channel (active low)
The pin has a pull-up resistor.
Set an upper limit of the maximum commutation frequency.
<Fst=Low>
F
MAX
=High or Open , Maximum commutation frequency f
MX
=
f
XT
/ (6×2 )
12
F
MAX
=Low , Maximum commutation frequency f
MX
=
f
XT
/(6
×
2 )
11
Description
3
OS
I
4
F
MAX
I
<Fst=High or Middle>
F
MAX
=High or Open , Maximum commutation frequency f
MX
=
f
XT
/ (6×2 )
9
F
MAX
=Low , Maximum commutation frequency f
MX
=
f
XT
/(6
×
2 )
The pin has a pull-up resistor.
8
5
V
SP
I
Duty cycle control input
0
≤
V
SP
≤
V
AD
(L): Output off
V
AD
(L)
≤
V
SP
≤
V
AD
(H): Set the PWM duty cycle according to the analog input.
V
AD
(H)
≤
V
SP
≤
V
DD
: Duty cycle
=
100% (31/32)
The pin has a pull-down resistor.
Rotation direction input
High
: Reverse rotation (U
→
W
→
V)
Low or open : Forward rotation (U
→
V
→
W)
The pin has a pull-down resistor.
Rotation speed sensing output
The pin is low at startup or upon a detection of a fault. This pin drives three pulses per
rotation (3 ppr) based on the back-EMF (electromotive force) sensing. (In the case of 4
pole motor, 6 pulse output per rotation.)
DC excitation time setting pins
When V
SP
≥
1 V (typ.), the START pin goes low to start DC excitation.
After the IP pin reaches V
DD
/2, the TB6575FNG moves from DC excitation to forced
commutation mode.
Connection pins for a crystal oscillator
These pins have a feedback resistor.
Lead angle control input
LA
=
Low or open : Lead angle of 7.5°
LA
=
high
: Lead angle of 15°
The pin has a pull-down resistor.
PWM output signal for the high-side (positive-side) transistor driving motor phase U
The PWM polarity can be specified by pin 3.
PWM output signal for the low-side (negative-side) transistor driving motor phase U
This signal is active high.
PWM output signal for the high-side (positive-side) transistor driving motor phase V
The PWM polarity can be specified by pin 3.
PWM output signal for the low-side (negative-side) transistor driving motor phase V
This signal is active high.
PWM output signal for the high-side (positive-side) transistor driving motor phase W
The PWM polarity can be specified by pin 3.
PWM output signal for the low-side (negative-side) transistor driving motor phase W
This signal is active high.
PWM output monitor pin
This pin drives PWM output whose duty cycle corresponds to the V
SP
input. It also
reflects the information at the OC pin.
Overlap commutation select pin
Low: Overlap commutation
The pin has a pull-up resistor.
High: 120° commutation
6
CW_CCW
I
7
FG_OUT
O
8
9
10
11
START
IP
X
T
X
Tin
O
I
⎯
⎯
12
LA
I
13
14
15
16
17
18
OUT_UP
OUT_UN
OUT_VP
OUT_VN
OUT_WP
OUT_WN
O
O
O
O
O
O
19
Duty
O
20
SEL_LAP
I
3
2006-3-6
TB6575FNG
Pin No.
21
22
Symbol
V
DD
OC
I/O
⎯
I
5-V power supply pin
Overcurrent detection input
The all PWM output signals are stopped when OC
≥
0.5 (V).
The pin has a pull-up resistor.
Position sensing input
3-phase voltage is applied to this pin.
The pin has a pull-up resistor.
Forced commutation frequency select pin
16
High or open : Forced commutation frequency f
ST
=
f
XT
/(6
×
2 )
17
Middle
: Forced commutation frequency f
ST
=
f
XT
/(6
×
2 )
18
Low
: Forced commutation frequency f
ST
=
f
XT
/(6
×
2 )
The pin has a pull-up resistor.
Description
23
WAVE
I
24
F
ST
I
Functional Description
1. Sensorless drive
On receiving an analog voltage command input, the rotor is aligned to a known position in DC excitation
mode, and then the rotation is started in forced commutation mode by applying a PWM signal to the motor.
As the rotor moves, back-EMF is acquired.
When a signal indicating the polarity of each of the phase voltages including back-EMF is applied to the
position signal input pin, automatic switching occurs from the forced commutation PWM signal to the
natural commutation PWM signal (which is generated based on the back-EMF sensing) to drive a BLDC
motor in sensorless mode.
2. Startup operation
When the motor is stationary, there is no back-EMF and the motor position is unknown. For this reason,
the rotor is aligned to a known position in DC excitation mode and then the rotation is started in forced
commutation mode. An external capacitor sets the times that the TB6575FNG stays in DC excitation and
forced commutation modes. Those times vary depending on the motor type and motor loading. Thus, they
must be adjusted experimentally.
V
SP
≥
1.0 (V)
V
SP
(5 pin)
V
SP
V
AD (L)
SC (2 pin)
START_SP (8 pin)
T
UP
V
DD
T
UP
(typ.)
=
C1
×
V
SP
/3.8
µA
(s)
IP (9 pin)
V
DD
2
(a) (b)
GND
V
SP
5
TB6575FNG
(a): DC excitation period : T
FIX
(typ.)
=
0.69
×
C1
×
R1 (s)
(b): Forced commutation period
2
C
1
9
R
1
C
2
8
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2006-3-6
TB6575FNG
The rotor is aligned to a known position in DC excitation mode for period (a), during which the IP pin voltage
decreases to half V
DD
level. The time constant for the period is determined by C
２
and R
1
. After that, switching
occurs to forced commutation mode represented by (b). The duty cycles for DC excitation and forced commutation
modes are determined according to the SC pin voltage.
When the number of turn of a motor is time more than
forced commutation frequency, the motor switches to sensorless mode.
The duty cycle for sensorless mode is
determined by the V
SP
value.
3. Forced commutation frequency
The forced commutation frequency for startup operation is set as follows.
The optimal frequency varies depending on the motor type and motor loading. Thus, It must be adjusted
experimentally.
F
ST
=
High or Open : Forced commutation frequency f
ST
=
f
XT
/(6
×
2
16
)
F
ST
=
Middle
: Forced commutation frequency f
ST
=
f
XT
/(6
×
2
17
)
F
ST
=
Low
: Forced commutation frequency f
ST
=
f
XT
/(6
×
2
18
)
T
FIX
*
f
XT
: Crystal oscillator frequency
4. PWM frequency
The PWM frequency is determined by an external oscillator.
PWM frequency (f
PWM
)
=
f
XT
/256
*
f
XT
: Crystal oscillator frequency
The PWM frequency must be sufficiently high, compared with the electrical frequency of the motor and
within the switching performance of the transistors.
OS
=
High or Open
PWM signal driving
high-side transistors
PWM signal driving
low-side transistors
Motor pin voltage
5. Speed control V
SP
pin
An analog voltage applied to the V
SP
pin is converted by the 6-bit AD converter to control the duty cycle
Duty cycle
of the PWM.
0
≤
V
DUTY
≤
V
AD
(L)
→
Duty cycle
=
0%
V
AD
(L)
≤
V
DUTY
≤
V
AD
(H)
→
Figure at the right (1/64 to 63/64)
V
AD
(H)
≤
V
DUTY
≤
V
DD
→
Duty cycle
=
100% (63/64)
100%
0%
VAD (L)
1 V (typ.)
VAD (H)
4 V (typ.)
VSP
5
2006-3-6
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