CXA1720Q Datasheet, PDF (1/26 Pages) Sony Corporation – Read/Write Amplifier (with Built-in Filters) for FDDs

CXA1720Q
Read/Write Amplifier (with Built-in Filters) for FDDs
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Description
The CXA1720Q is an IC for use with floppy disk
32 pin QFP (Plastic)
drives, and contains a Read circuit (with built-in
filters), Write circuit, Erase circuit, and supply
voltage detection circuit, all into a single chip.
Features
• Single 5 V power supply.
• Filter system can be switched among four modes:
1M/2M, and inner track/outer track. This allows for
a significant reduction in the number of external
parts such as differentiator constants, low-pass
filters, and switches. (Compared with conventional
Sony products, the number of parts has been
reduced by one-half.)
• Filter characteristics can be customized.
• Low pre-amplifier input conversion noise voltage of
2.0 nV/ √ Hz (typ.) keeps Read data output jitter to
a minimum. The pre-amplifier voltage gain can be
selected as either 100× or 200×.
• The monostable multivibrator No. 1 pulse width
switching function for the time domain filter permits
switching between 1M and 2M mode.
• Write current switching function permits switching
of the Write current among four modes: 1M/2M
and inner track/outer track. (Filter inner track/outer
track switching is separate.)
Block Diagram and Pin Configuration
• Supply voltage detection circuit prohibits error
writing during power ON/OFF or abnormal voltage.
• Power consumption is kept down to 115 mW (typ.)
and this IC is suitable for use with battery-driven
FDDs.
• Built in Time constant capacitors for monostable
multivibrator Nos. 1 and 2. (The pulse width for
monostable multivibrator No. 2 is fixed.)
• Power saving function reduces power consumption
when the IC is not in use. When in power saving
mode (5 mW typ.), only the power supply ON/OFF
detector functions.
• The Write driver has a built-in reset circuit. When
the mode is switched from Read mode to Write
mode, the Write current flows from head 0A if head
side 0 is selected and from head 1A if head side 1
is selected.
W/C 1
SET
25
W/C 1
COMP 26
W/C 2
SET 27
W/C 2
COMP
28
D.GND 29
ERASE
OUT 0
30
ERASE
OUT 1
31
POWER 32
SAVE
24 23 22 21 20 19 18 17
PREAMP
WRITE
DRIVER
FILTER
DIFF+LPF
(BPF)
16
FILTER
OUT B
15
COMP
IN B
14
COMP
IN A
13 A.GND
ERASE
DRIVER
POWER
MONITOR
CONTROL
LOGIC
12 MMVA
11
FILTER
SET
10 Vcc
9 ^HIGH
DENSITY
1
2
3
4
5
6
7
8
Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by
any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the
operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.
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E93717-TE