Absolute Maximum Ratings
Load Supply Voltage, V
BB
. . . . . . . . . . . . 15 V
Output Current
1
, I
OUT . . . . . . . . . . . . . . . . . . . . .
1.4 A
Peak Output Current (Brake)
2
, I
OUT(BRK)
. 3.0 A
Period
2
for I
OUT(BRK)
to fall from
3.0 A to 1.4 A . . . . . . . . . . . . . . . 800 ms
Logic Supply Voltage, V
DD
. . . . . . . . . . . 7.0 V
Logic Input Voltage Range, V
IN
(continuous) . . . . . . -0.3 V to V
DD
+ 0.3 V
(t
w
<30 ns) . . . . . . . -1.0 V to V
DD
+ 1.0 V
Package Power Dissipation, P
D
. . See Graph
Operating Temperature, T
A
. . . -20C to +85C
Junction Temperature
3
, T
J
. . . . . . . . . +150C
Storage Temperature,T
S
. . . . -55C to +150C
1
Output current rating may be restricted to a value
determined by system concerns and factors. These
include: system duty cycle and timing, ambient
temperature, and use of any heatsinking and/or forced
cooling. For reliable operation, the specified maximum
junction temperature should not be exceeded.
2
Peak output current is a transient condition that
occurs during braking when the motor acts as a
generator. The 3 A level is based on the maximum
peak of a sine wave that is damped. The maximum
period between the initial brake being applied and the
current through the drivers falling to 1.4 A should not
exceed 800 ms. See Braking section for more
information.
3
Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated, but should
be avoided.
Data Sheet
26301.5B
The A8904SLB and A8904SLP are three-phase brushless dc motor
controller/drivers designed for applications where accurate control of high-
speed motors is required. The three half-bridge outputs are low on-resistance
n-channel DMOS devices capable of driving up to 1.2 A. The A8904 provides
complete, reliable, self-contained back-EMF sensing, motor startup and
running algorithms. A programmable digital frequency-locked loop speed
control circuit together with the linear current control circuitry provides
precise motor speed regulation.
A serial port allows the user to program various features and modes of
operation, such as the speed control parameters, startup current limit, sleep
mode, direction, and diagnostic modes.
The A8904 is fabricated in Allegro's BCD (Bipolar CMOS DMOS)
process, an advanced mixed-signal technology that combines bipolar, analog
and digital CMOS, and DMOS power devices. The A8904SLB is provided in
a 24-lead wide-body SOIC batwing package. The A8904SLP is provided in a
thin (<1.2 mm), 28-lead SSOP package with an exposed thermal pad. Each
package type is available in a lead-free version (100% matte tin leadframe).
Features
Pin-for-pin replacement for A8902CLBA
Startup commutation circuitry
Sensorless commutation circuitry
Option of external sector data tachometer signal
Option of external speed control
Oscillator operation up to 20 MHz
Programmable overcurrent limit
Transconductance gain options: 500 mA/V or 250 mA/V
Programmable watchdog timer
Directional control
Serial Port Interface
TTL-compatible inputs
System diagnostics data out ported in real time
Dynamic braking through serial port or external terminal
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
8904
A8904SLB
(SOIC)
Always order by complete part number:
Part Number
Package
A8904SLB
24-pin batwing SOIC
A8904SLB-T
24-pin batwing SOIC; Lead-free
A8904SLP
28-pin SSOP with Exposed Thermal Pad
A8904SLP-T
24-pin SSOP with Exposed Thermal Pad; Lead-free
8904
3-PHASE BRUSHLESS DC
MOTOR CONTROLLER/DRIVER
www.allegromicro.com
5
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
C
WD
Current
I
CWD
Charging, D26 = 0, D27 = 0
-9.0
-10
-11
A
Charging, D26 = 0, D27 =1
-18
-20
-22
A
Charging, D26 = 1 D27 = 0
-27
-30
-33
A
Charging, D26 = 1, D27 =1
-36
-40
-44
A
C
WD
Threshold Voltage
V
TL
0.22
0.25
0.28
V
V
TH
2.25
2.5
2.75
V
Max. FLL Oscillator Frequency
f
OSC
20*
--
--
MHz
Oscillator High Duration
ton
20
--
--
ns
Oscillator Low Duration
toff
20
--
--
ns
Maximum Output Current
I
OUT
(MAX)
D3 = 0, D4 = 0, D28 = 0
1.0
1.2
1.4
A
D3 = 0, D4 = 1, D28 = 0
0.9
1.0
1.1
A
D3 = 1, D4 = 0, D28 = 0
500
600
700
mA
D3 = 1, D4 = 1, D28 = 0
--
250
--
mA
D3 = 0, D4 = 0, D28 = 1
500
600
700
mA
D3 = 0, D4 = 1, D28 = 1
415
500
585
mA
D3 = 1, D4 = 0, D28 = 1
--
300
--
mA
D3 = 1, D4 = 1, D28 = 1
--
125
--
mA
Transconductance Gain
g
m
D28 = 1
210
250
290
mA/V
D28 = 0
420
500
580
mA/V
Centertap Resistors
R
CT
5.0
10
13
k
Back-EMF Threshold with respect
--
5.0
20
37
mV
to V
CTAP
at FCOM transition
-5.0
-20
-37
mV
ELECTRICAL CHARACTERISTICS continued
Negative current is defined as coming out of (sourcing) the specified device terminal.
* Operation at an oscillator frequency greater than the specified minimum value is possible but not waranteed.
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