SI9961A Просмотр технического описания (PDF) - Vishay Semiconductors
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SI9961A Datasheet PDF : 10 Pages
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Product is End of Life 12/2014
12-V Voice Coil Motor Driver
Si9961A
Vishay Siliconix
DESCRIPTION
The Si9961A is a linear actuator (voice coil motor) driver suit-
able for use in disk drive head positioning systems. The
Si9961A contains all of the power and control circuitry nec-
essary to drive the VCM that is typically found in 31/2 inch
hard disk drives and optical disk drives. The driver is capable
of delivering 1.8 A at a nominal supply of 12 V.
The Si9961A provides all necessary functions including a
motor current sense amplifier, a loop compensation amplifier
and a power amplifier featuring four complementary MOS-
FETs in a H-bridge configuration. The output crossover pro-
tection ensures no cross-conducting current and true Class
B operation during linear tracking. Externally programmable
gain switch at the input summing junction increases the res-
olution and dynamic range for a given DAC. The head retract
circuitry can be activated by either an undervoltage condition
or an external command. An external resistor is required to
set the VCM current during retract.
The Si9961A is constructed on a self-isolated BiC/DMOS
power IC process. The IC is available in both standard and
lead (Pb)-free, 24-pin SO packages for operation over the
commercial, C suffix (0 to 70 °C) temperature range.
FEATURES
• 1.8 A H-Bridge Output
• Class B Linear Operation
• Externally Programmable Gain and Bandwidth
• Undervoltage Head Retract
• Programmable Retract Current
• Low Standby Current
• Rail-to-Rail Output Swing
• Single 12 V Supply
• System Voltage Monitor with Fault Output
FUNCTIONAL BLOCK DIAGRAM
EXT
V+
VREF VREF_
8
7
12
4
FAULT
VCC
5
23
IA2-
RETRACT 9
IRET
6
Enable 11
OA2 22
GAIN 10
SELECT
Voltage
Monitor
- A2
R
+
VR
VR
Acceleration Error
R
VR
VR
8R
+
A4
-
Retract
Control
-
A5
+
7 R A3 -
+
VDD
18
Q1
Q3
Q2
Q4
17 OUTPUT
A
19 OUTPUT
B
1
RINH
2
RINL
Document Number: 70014
S-40845-Rev. H, 03-May-04
24
RFB
3
ISENSE
OUT
13
21
15 14
16 20
ISENSE ISENSE SA GND SB
IN+ IN-
www.vishay.com
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