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
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.)
HEAD 1A
HEAD 0A
HEAD 0B
HEAD 1B
32 pin QFP (Plastic)
•
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.
PREAMP
OUT
Block Diagram and Pin Configuration
24
23
22
21
20
19
18
FILTER
OUT A
17
VREF
HIGH
GAIN
W/C 1 25
SET
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
POWER
MONITOR
WRITE
DRIVER
PREAMP
FILTER
DIFF+LPF
(BPF)
FILTER
16 OUT B
15 COMP
IN B
14 COMP
IN A
13 A.GND
COMP
ERASE
DRIVER
12 MMVA
FILTER
11 SET
CONTROL
LOGIC
TIME
DOMAIN
FILTER
10 Vcc
HIGH
DENSITY
9
1
POWER
ON
2
WRITE
DATA
3
READ
DATA
4
WRITE
CURRENT
5
WRITE
GATE
6
ERASE
GATE
7
SIDE 1
8
FILTER
CONTROL
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 ]
