CXA1720Q
Read/Write Amplifier (with Built-in Filters) for FDDs
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Description
32 pin QFP (Plastic)
The CXA1720Q is an IC for use with floppy disk
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
• Supply voltage detection circuit prohibits error
a significant reduction in the number of external
writing during power ON/OFF or abnormal voltage.
parts such as differentiator constants, low-pass
• Power consumption is kept down to 115 mW (typ.)
filters, and switches. (Compared with conventional
and this IC is suitable for use with battery-driven
Sony products, the number of parts has been
FDDs.
reduced by one-half.)
• Built in Time constant capacitors for monostable
• Filter characteristics can be customized.
multivibrator Nos. 1 and 2. (The pulse width for
• Low pre-amplifier input conversion noise voltage of
monostable multivibrator No. 2 is fixed.)
2.0 nV/ √ Hz (typ.) keeps Read data output jitter to
• Power saving function reduces power consumption
a minimum. The pre-amplifier voltage gain can be
when the IC is not in use. When in power saving
selected as either 100× or 200×.
mode (5 mW typ.), only the power supply ON/OFF
• The monostable multivibrator No. 1 pulse width
detector functions.
switching function for the time domain filter permits
• The Write driver has a built-in reset circuit. When
switching between 1M and 2M mode.
the mode is switched from Read mode to Write
• Write current switching function permits switching
mode, the Write current flows from head 0A if head
of the Write current among four modes: 1M/2M
side 0 is selected and from head 1A if head side 1
and inner track/outer track. (Filter inner track/outer
is selected.
track switching is separate.)
Block Diagram and Pin Configuration
24
23
22
21
20
19
18
17
FILTER
OUT B
W/C 1
SET
PREAMP
25
26
27
28
29
30
31
32
16
15
14
13
12
11
10
9
FILTER
DIFF+LPF
(BPF)
W/C 1
COMP
COMP
IN B
W/C 2
SET
COMP
IN A
WRITE
DRIVER
W/C 2
COMP
A.GND
MMVA
D.GND
ERASE
DRIVER
ERASE
OUT 0
FILTER
SET
ERASE
OUT 1
CONTROL
LOGIC
POWER
MONITOR
Vcc
HIGH
DENSITY
POWER
SAVE
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.
—1—
E93717-TE
SONY [ SONY CORPORATION ]
