NTE3470
Integrated Circuit
Floppy Disk Read Amplifier System
Description:
The NTE3470 is a monolithic READ Amplifier System for obtaining digital information from floppy disk
storage. It is designed to accept the differential AC signal produced by the magnetic head and pro-
duce a digital output pulse that corresponds to each peak of the input signal. The gain stage amplifies
the input waveform and applies it to an external filter network, enabling the active differentiator and
time domain filter to produce the desired output.
Features:
D
Combines All the Active Circuitry to Perform the Floppy Disk Read Amplifier Function in One Circuit
D
Improved (Positive) Gain T
C
and Tolerance
D
Improved Input Common Mode
Absolute Maximum Ratings: (T
A
= +25
C, Note 1 unless otherwise specified)
Power Supply Voltage (Pin11), V
CC1
7V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Voltage (Pin18), V
CC2
16V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Voltage (Pin1 and Pin2), V
I
0.2 to +7.0V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output Voltage (Pin10), V
O
0.2 to +7.0V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Ambient Temperature Range, T
A
0
to +70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Junction Temperature, T
J
+150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Temperature Range, T
stg
65
to +150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Note 1. "Absolute Maximum Ratings" are those values beyond which the safety of the device cannot
be guaranteed. They are not meant to imply that the device should be operated at these lim-
its. The table of "Electrical Characteristics" provides conditions for actual device operation.
Recommended Operating Conditions:
Power Supply Voltage, V
CC
(V
CC1
)
+4.75 to +5.25V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(V
CC2
)
+10 to +14V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Ambient Temperature Range, T
A
0
to +70
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Characteristics: (T
A
= 0
to +70
C, V
CC1
= 4.75 to 5.25V, V
CC2
= 10 to 14V unless
otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Differential Voltage Gain
A
VD
f = 200kHz, V
iD
= 7mV
RMS
80
100
130
V/V
Input Base Current
I
IB
10
25
A
Input Common Mode Range,
Linear Operation
v
iCM
5% Max THD
0.1
1.5
V
Differential Input Voltage, Linear Op-
eration
v
iD
5% Max THD
25
mV
PP
Output Voltage Swing Differential
v
oD
3
4
V
PP
Output Source Current, Toggled
I
O
8.0
mA
Output Sink Current (Pin16 and Pin17)
I
OS
2.8
4.0
mA
Small Signal Input Resistance
r
i
T
A
= +25
C
100
250
k
Small Signal Output Resistance,
Single Ended
r
o
T
A
= +25
C, V
CC1
= 5V,
V
CC2
= 12V
15
Bandwidth, 3dB
BW
v
iD
= 2mV
RMS,
T
A
= +25
C,
V
CC1
= 5V, V
CC2
= 12V
10
MHz
Common Mode Rejection Ratio
CMRR
T
A
= +25
C, f = 100kHz,
A
VD
= 40dB, v
in
= 200mV
PP
,
V
CC1
= 5V, V
CC2
= 12V
50
dB
V
CC1
Supply Rejection Ratio
T
A
= +25
C, V
CC2
= 12V,
4.75V
V
CC1
5.25V, A
VD
= 40dB
50
dB
V
CC2
Supply Rejection Ratio
T
A
= +25
C, V
CC1
= 5V,
10V
V
CC2
14V, A
VD
= 40dB
50
dB
Differential Output Offset
V
DO
T
A
= +25
C, v
iD
= v
in
= 0V
0.4
V
Common Mode Output Offset
V
CO
v
iD
= v
in
= 0V, Differential and
Common Mode
3.0
V
Differential Noise Voltage Referred
to Input
e
n
T
A
= +25
C, BW = 10Hz to 1MHz
15
V
RMS
Supply Current
I
CC
V
CC1
= 5.25V, S
1
to Pin12 or Pin13
40
mA
V
CC2
= 14V
4.8
mA
Active Differentiator Section
Differentiator Output Sink Current,
Pin12 and Pin13
I
OD
V
OD
= V
CC1
1.0
1.4
mA
Peak Shift
PS
Note 2
5
%
Differentiator Input Resistance,
Differential
r
iD
30
k
Differentiator Output Resistance,
Differential
r
oD
T
A
= +25
C
40
Note 2. f = 250kHz, v
iD
= 1V
PP
, i
cap
= 500
A
where PS = 1/2
x 100%
t
PS1
t
PS2
t
PS1
+ t
PS2
V
CC1
= 5V, V
CC2
= 12V
Electrical Characteristics (Cont'd): (T
A
= 0
to +70
C, V
CC1
= 4.75 to 5.25V, V
CC2
= 10 to 14V
unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Digital Section
Output Voltage High Logic Level, Pin10
V
OH
V
CC1
= 4.75V, V
CC2
= 12V,
I
OH
= 0.4mA
2.7
V
Output Voltage Low Logic Level, Pin10
V
OL
V
CC1
= 4.75V, V
CC2
= 12V,
I
OH
= 8mA
0.5
V
Output Rise Time, Pin10
t
TLH
20
ns
Output Fall Time, Pin10
t
THL
25
ns
Timing Range Mono #1 (t
1A
and t
1B
)
t
1A
, t
1B
500
4000
ns
Timing Accuracy Mono #1
E
t1
t1 = 1
s = 0.625 R1C1 + 200ns,
Note 3, Note 4, Note 5
85
115
%
Timing Range Mono #2
t2
150
1000
ns
Timing Accuracy Mono #2
E
t2
t2 = 200ns = 0.625 R2C2,
Note 6, Note 7
85
115
%
Note 3. R1 = 6.4k
, C1 = 200pF.
Note 4. Accuracy guaranteed for R1 in the range 1.5k
R1
10k
and C1 in the range 150pF
C1
680pF.
Note 5. To minimize current transients, C1 should be kept as small as is convenient.
Note 6. R2 = 1.6k
, C2 = 200pF.
Note 7. Accuracy guaranteed for R2 in the range 1.5k
R2
10k
and C2 in the range 100pF
C1
800pF.
V
CC1
V
CC2
Pin Connection Diagram
Offset Decoupling
Amplifier Input
Offset Decoupling
OneShot Component Mono #2
Differentiator Component
1
2
3
4
Amplifier Input
5
GND
6
OneShot Component Mono #1
7
OneShot Component Mono #1
8
OneShot Component Mono #2
18
17
16
15
Amplifier Output
Amplifier Output
Active Differentiator Input
14
Active Differentiator Input
13
Differentiator Component
12
11
9
10
Data Output
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