A8904SLP Allegro Microsystems Inc, A8904SLP Datasheet - Page 9

• Manufacturer Part Number: A8904SLP
• Description: IC CTRLR/DRVR DC MOTOR 28TSSOP
• Manufacturer: Allegro Microsystems Inc

Specifications of A8904SLP

• 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: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

A8904
* For the LP package, ground terminals 1, 8, and 22 must be connected together externally.
ANALOG GROUND
POWER GROUND
DIGITAL GROUND
LOGIC SUPPLY
Terminal Name
LOAD SUPPLY
SECTOR DATA
CHIP SELECT
OSCILLATOR
CENTERTAP
DATA OUT
GROUND
GROUND
DATA IN
BRAKE
FILTER
RESET
CLOCK
OUT
OUT
OUT
C
C
C
C
C
NC
NC
NC
NC
NC
RES
WD
D2
ST
D1
A
B
C
Function
V
One of two capacitors used to generate the ideal commutation points from
the back-EMF zero crossing points.
Timing capacitor used by the watchdog circuit to blank out the back-EMF
comparators during commutation transients, and to detect incorrect motor
position.
Start-up oscillator timing capacitor.
No( internal) connection.
Power amplifi er A output to motor.
No (internal) connection.
Power and logic ground and thermal heat sink.
Power ground.
No (internal) connection.
Power amplifi er B output to motor.
Power amplifi er C output to motor.
Motor centertap connection for back-EMF detection circuitry.
Active low turns ON all three sink drivers shorting the motor windings to
ground. External capacitor and resistor at B
The brake function can also be controlled via the serial port.
External reservoir capacitor used to hold charge to drive the source drivers’
gates. Also provides power for brake circuit.
Analog ground.
Analog voltage input/output to control motor current. Also, compensation node
for internal speed control loop.
External tachometer input. Can use sector or index pulses from disk to
provide precise motor speed feedback to internal frequency-locked loop.
V
Clock input for the speed reference counter.
Thermal shutdown indicator, FCOM, TACH, or SYNC signals available in
real time, controlled by 2-bit multiplexer via serial port.
No (internal) connection.
Power and logic ground and thermal heat sink.
Logic ground.
When pulled low forces the chip into sleep mode; clears all serial port bits.
No (internal) connection.
Strobe input (active low) for data word.
Clock input for serial port.
Sequential data input for the serial port.
One of two capacitors used to generate the ideal commutation points from
the back-EMF zero crossing points.
BB
DD
; the 5 V or 12 V motor supply.
; the 5 V logic supply.
3-Phase Brushless DC Motor Controller/Driver
Terminal Functions
RAKE
provide brake delay.
with Back EMF Sensing
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
(SOIC)
18-19
6-7
LB
10
11
12
13
14
15
16
17
20
21
22
23
24
1
2
3
4
–
5
–
–
–
8
9
–
–
–
–
(TSSOP)
22*
LP
15
16
17
18
19
20
21
23
24
25
26
27
28
10
11
12
13
14
1*
8*
–
2
3
4
5
6
7
–
9
8