A8904SLB Allegro Microsystems Inc, A8904SLB Datasheet - Page 15

• Manufacturer Part Number: A8904SLB
• Description: IC CTRLR/DRIVER DC MOTOR 24SOIC
• Manufacturer: Allegro Microsystems Inc

Specifications of A8904SLB

• Applications: DC Motor Driver, Brushless (BLDC), 3 Phase
• Number Of Outputs: 1
• Current - Output: ±1.4A
• Voltage - Load: 4 V ~ 14 V
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

A8904
the default condition for A8902-A operation. The only consid-
eration when using the A8904 in an A8902-A application is to
ensure the minimum CHIP SELECT high time is at least 500 ns.
allows the device to be powered down when not in use.
Only. When in the step-only mode the back-EMF commutation
circuitry is disabled and the start-up oscillator commutates the
power outputs. This mode is intended for device and system
testing.
D4; D28 sets the transconductance gain.
number to produce the corresponding REF signal, which indi-
cates the desired motor speed.
D3
D0 - Sleep/Run Mode; LOW = Sleep, HIGH = Run. This bit
D1 - Step Mode; LOW = Normal Operation, HIGH = Step
D2 - Brake; LOW = Run, HIGH = Brake.
D3, D4, and D28 - The output current limit is set by D3 &
0
0
1
1
0
0
1
1
D5 to D18 - 14-bit word, active low. Programs the count
D4
0
1
0
1
0
1
0
1
Bit number
D28
0
0
0
0
1
1
1
1
D10
D11
D12
D13
D14
D15
D16
D17
D18
D5
D6
D7
D8
D9
Current limit Transconductance
(typical)
600 mA
250 mA
600 mA
500 mA
300 mA
125 mA
1.2 A
1.0 A
Count number
131,072
16,384
32,768
65,536
1,024
2,048
4,096
8,192
3-Phase Brushless DC Motor Controller/Driver
128
256
512
16
32
64
Functional Description (cont’d)
500 mA/V
500 mA/V
500 mA/V
500 mA/V
250 mA/V
250 mA/V
250 mA/V
250 mA/V
gain
speed signal, HIGH = external sector data.
once-around FCOM counter.
See DATA OUT Section for status defi nitions.
technique, HIGH = External (internal control disabled).
dog capacitor. This function is used for adjusting the blanking
duration and also the watchdog commutation period.
D28 - Programs the transconductance gain. LOW = 500 mA/V,
HIGH = 250 mA/V.
serial port bits are reset to LOW and the part operates in sleep
mode.
condition occurs, all the serial port bits are reset to LOW and the
part operates in sleep mode.
a voltage rail above the load supply for driving the high-side
DMOS gates. In addition the charge pump supply capacitor,
C
conditions. C
RES,
D26
D22
D19 - Speed control mode; LOW = internal, once-around
D20 and D21 - Programs the number of motor poles for the
D22 and D23 - Controls the multiplexer for DATA OUT.
D24 - Speed Reference. LOW = Internal, using back-EMF
D25 - Direction. LOW = Forward, HIGH = Reverse.
D26 and D27 - Programs the charging current for the watch-
Reset. When the RESET terminal is pulled low, all the
Undervoltage lockout, V
Charge pump. The charge pump is required to provide
0
0
1
1
0
0
1
1
also powers the brake control circuit during power-down
D27
D23
0
1
0
1
RES
0
1
0
1
with Back EMF Sensing
D20
should be 220 nF.
0
0
1
1
DATA OUT
TACH (once around or sector) signal
Thermal shutdown
SYNC signal
FCOM signal
Watchdog charge current (typical)
-10 μA
-20 μA
-30 μA
-40 μA
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
D21
0
1
0
1
DD
. When an undervoltage
Motor poles
16
12
8
4
14