8958 Datasheet, PDF (1/8 Pages) Allegro MicroSystems – VOICE COIL MOTOR DRIVER

8958
LOGIC
SUPPLY
1
V_CC
INHIBIT
UV₁
2
1.5 V ₊
3
UV₂ 4
LIMIT 5
GROUND_AB 6
GROUND_AB 7
PARK ₈
VOLTAGE
SENSE_IN– 99
IN _A+ 10 ₊
A
IN _A– 11
-
OUT _{A 12}
24 SENSE _OUT
23 ^PARK
DRIVE
22 PARK
21 GROUND
20 PWR OK
19 GROUND_AB
18 GROUND_AB
17 SENSE_IN+
+ ¹⁶
B
- 15
V_BB 14
13
IN _B+
IN _B–
LOAD
SUPPLY
OUT _B
Dwg. PP-054
ABSOLUTE MAXIMUM RATINGS
at T_A = 25°C
Supply Voltages, V_BB and V_CC ............... 16 V
Output Current, I_OUT ............................ ±1.0 A
Park Drive Output Current, I_PARK
Continuous ................................ 250 mA
Peak .............................................. 1.0 A
Amplifier Input Voltage Range,
V_IN ..................................... -2.0 V to V_CC
Sense Input Voltage Range,
V_{SENSE IN} ............................ -0.3 V to V_CC
Comparator and Digital Inputs,
V_IN .................................... -0.3 V to 10 V
I_IN .............................................. ±10 mA
Power OK Output, V_CEX ......................... 20 V
I_C ................................................. 30 mA
Output Clamp Diode Current,
I_F (pulsed) ..................................... 1.0 A
Package Power Dissipation, P_D .. See Graph
Operating Temperature Range,
T_A ...................................... 0°C to +70°C
Junction Temperature, T_J ................... 150°C*
Storage Temperature Range,
T_S ................................ -55°C to +150°C
* Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated but
should be avoided.
VOICE COIL MOTOR DRIVER
Providing control and drive of the voice coil motor used for head
positioning in disk drive applications, the A8958CLB is a full-bridge
driver which can be configured so that its output current is a direct
function of an externally applied control voltage or current. This linear
current control function is supplemented by additional circuitry to
protect the heads and the data disk during system failure or normal
system shutdown.
The two ±800 mA driver outputs provide very-low saturation voltage
drops and precise current control utilizing a single current-sensing
resistor connected in series with the load. Under-voltage lockout
disables the system in a controlled sequence if a fault condition occurs.
When activated by the under-voltage comparator, or a park com-
mand, the output power drivers change from a controlled current to a
user-determined constant park voltage. Other features include a power
ok flag, a limit input to force the outputs to their maximum level in either
polarity, an over-riding output disable to shut down both power amplifi-
ers and reduce quiescent supply current, and internal thermal shutdown
which disables the load (but still allowing the head to be parked) in the
event of excessive junction temperatures. The load is re-enabled when
the junction temperature returns to a safe level.
The A8958CLB is supplied in a 24-lead power SOIC for surface-
mount applications. The copper batwing construction provides for
maximum package power dissipation in a minimum package size. It is
rated for continuous operation over the temperature range of 0°C to
+70°C.
FEATURES
s Controlled-Velocity Head Parking
s Zero Deadband
s High Transconductance Bandwidth
s User-Adjustable Transconductance Gain
s ±800 mA Load Current
s Dual Under-Voltage Monitors
with Flag and User-Selectable Trip Points
s Internal Thermal Shutdown Circuitry
s Replaces UC3175
Always order by complete part number, e.g., A8958CLB .