A8902CLBA Allegro MicroSystems, A8902CLBA Datasheet - Page 9

• Manufacturer Part Number: A8902CLBA
• Description: 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH BACK-EMF SENSING
• Manufacturer: Allegro MicroSystems

and diagnostic modes to the A8902CLBA. The serial port DATA IN is
enabled/disabled by the CHIP SELECT terminal. When CHIP SE-
LECT is high the serial port is disabled and the chip is not affected by
changes in data at the DATA IN or CLOCK terminals.
prior to the CHIP SELECT terminal going low. Once CHIP SELECT
goes low, information on the DATA IN terminal is read into the shift
register on the positive-going transition of the CLOCK. There are 24
bits in the serial input port.
upon the low-to-high transition of the CHIP SELECT terminal at the
end of the write cycle. D0 will be the last bit written to the serial port.
D0- Sleep/Run Mode; LOW = Sleep, HIGH = Run
D1- Step Mode; LOW = Normal Operation, HIGH = Step Only
D2- Brake; LOW = Run, HIGH = Brake.
D3 and D4 - These two bits set the output current limit:
D5 thru D18-This 14-bit word (active low) programs the
desired motor speed.
Serial Port. The serial port functions to write various operational
To write data to the serial port, the CLOCK terminal should be low
Data written into the serial port is latched and becomes active
This bit allows the device to be powered down when not in use.
When in the step-only mode the back-EMF commutation circuitry
is disabled and the power outputs are commutated by the start-
up oscillator. This mode is intended for device and system
testing.
D3
0
0
1
1
D4
0
1
0
1
Current Limit
600 mA
250 mA
1.2 A
1 A
REF
time to set
MOTOR CONTROLLER/DRIVER
D19-Speed-control mode switch;
D20 and D21-These bits program the number
D22 and D23-Controls the multiplexer for
low clears all serial port bits, including the D0
latch, which puts the A8902CLBA in the sleep
mode.
D22
3-PHASE BRUSHLESS DC
0
0
1
1
Reset. The RESET terminal when pulled
LOW = internal once-around speed signal,
HIGH = external sector data.
of motor poles for the once-around
counter:
DATA OUT:
Bit Number
D23
D20
D10
D11
D12
D13
D14
D15
D16
D17
D18
0
1
0
1
D5
D6
D7
D8
D9
0
0
1
1
TACH (once around or sector)
D21
0
1
0
1
Thermal Shutdown
Count Number
DATA OUT
Motor Poles
131 072
FCOM
SYNC
16 384
32 768
65 536
1 024
2 048
4 096
8 192
128
256
512
8902–A
16
32
64
16
12
8
–
FCOM