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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 produce 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 TC and Tolerance
D Improved Input Common Mode
Absolute Maximum Ratings: (TA = +25°C, Note 1 unless otherwise specified)
Power Supply Voltage (Pin11), V
Power Supply Voltage (Pin18), V
Input Voltage (Pin1 and Pin2), V
Output Voltage (Pin10), V
O
CC1
CC2
I
Operating Ambient Temperature Range, T
Operating Junction Temperature, T
Storage Temperature Range, T
J
stg
–0.2 to +7.0V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
–0.2 to +7.0V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A
0° to +70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
–65° to +150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
+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 limits. The table of “Electrical Characteristics” provides conditions for actual device operation.
Recommended Operating Conditions:
Power Supply Voltage, V
(V
(V
) +4.75 to +5.25V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CC1
) +10 to +14V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CC2
Operating Ambient Temperature Range, T
CC
A
0° to +70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Electrical Characteristics: (TA = 0° to +70°C, V
otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Unit
= 4.75 to 5.25V, V
CC1
= 10 to 14V unless
CC2
Differential Voltage Gain A
Input Base Current I
Input Common Mode Range,
v
f = 200kHz, ViD = 7mV
VD
IB
5% Max THD –0.1 – 1.5 V
iCM
Linear Operation
Differential Input Voltage, Linear Op-
v
5% Max THD – – 25 mV
iD
eration
Output Voltage Swing Differential v
Output Source Current, Toggled I
Output Sink Current (Pin16 and Pin17) I
Small Signal Input Resistance r
Small Signal Output Resistance,
Single Ended
Bandwidth, –3dB BW viD = 2mV
oD
O
OS
TA = +25°C 100 250 – kΩ
i
r
TA = +25°C, V
o
V
V
CC2
CC1
= 12V
RMS, TA
= 5V, V
CC1
CC2
= 5V,
= +25°C,
= 12V
Common Mode Rejection Ratio CMRR TA = +25°C, f = 100kHz,
AVD = 40dB, vin = 200mV
V
CC1
V
Supply Rejection Ratio TA = +25°C, V
CC1
4.75V ≤ V
V
Supply Rejection Ratio TA = +25°C, V
CC2
10V ≤ V
Differential Output Offset V
Common Mode Output Offset V
TA = +25°C, viD = vin = 0V – – 0.4 V
DO
viD = vin = 0V, Differential and
CO
= 5V, V
CC1
CC2
= 12V
CC2
= 12V,
CC2
≤ 5.25V, AVD = 40dB
= 5V,
CC1
≤ 14V, AVD = 40dB
Common Mode
RMS
P–P
80 100 130 V/V
– –10 –25 µA
P–P
3 4 – V
P–P
– 8.0 – mA
2.8 4.0 – mA
– 15 – Ω
10 – – MHz
50 – – dB
,
50 – – dB
50 – – dB
– 3.0 – V
Differential Noise Voltage Referred
e
TA = +25°C, BW = 10Hz to 1MHz – 15 – µV
n
to Input
Supply Current I
CC
V
= 5.25V, S1 to Pin12 or Pin13 – 40 – mA
CC1
V
= 14V – 4.8 – mA
CC2
Active Differentiator Section
Differentiator Output Sink Current,
I
OD
VOD = V
CC1
1.0 1.4 – mA
Pin12 and Pin13
Peak Shift PS Note 2 – – 5 %
Differentiator Input Resistance,
r
iD
– 30 – kΩ
Differential
Differentiator Output Resistance,
r
TA = +25°C – 40 – Ω
oD
Differential
Note 2. f = 250kHz, viD = 1V
t
CC2
PS1
t
PS1
= 12V
where PS = 1/2 x 100%
V
= 5V, V
CC1
P–P
– t
+ t
, i
PS2
PS2
cap
= 500µA
RMS
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Electrical Characteristics (Cont’d): (TA = 0° to +70°C, V
unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Unit
Digital Section
= 4.75 to 5.25V, V
CC1
= 10 to 14V
CC2
Output Voltage High Logic Level, Pin10 V
Output Voltage Low Logic Level, Pin10 V
Output Rise Time, Pin10 t
Output Fall Time, Pin10 t
Timing Range Mono #1 (t1A and t1B) t1A, t
Timing Accuracy Mono #1 E
Timing Range Mono #2 t2 150 – 1000 ns
Timing Accuracy Mono #2 E
TLH
THL
V
OH
OL
1B
t1
t2
= 4.75V, V
CC1
= –0.4mA
I
OH
V
= 4.75V, V
CC1
IOH = 8mA
t1 = 1µs = 0.625 R1C1 + 200ns,
Note 3, Note 4, Note 5
t2 = 200ns = 0.625 R2C2,
Note 6, Note 7
CC2
CC2
= 12V,
= 12V,
2.7 – – V
– – 0.5 V
– – 20 ns
– – 25 ns
500 – 4000 ns
85 – 115 %
85 – 115 %
Note 3. R1 = 6.4kΩ, C1 = 200pF.
Note 4. Accuracy guaranteed for R1 in the range 1.5kΩ ≤ R1 ≤ 10kΩ 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 = 1.6kΩ, C2 = 200pF.
Note 7. Accuracy guaranteed for R2 in the range 1.5kΩ ≤ R2 ≤ 10kΩ and C2 in the range 100pF ≤
C1 ≤ 800pF.
Pin Connection Diagram
Amplifier Input
Amplifier Input
Offset Decoupling
Offset Decoupling
One–Shot Component Mono #1
One–Shot Component Mono #1
One–Shot Component Mono #2
1
2
3
4
5GND
6
7
8One–Shot Component Mono #2
18
17
16
15
14
13
12
11
9 10
V
CC2
Amplifier Output
Amplifier Output
Active Differentiator Input
Active Differentiator Input
Differentiator Component
Differentiator Component
V
CC1
Data Output
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18 10
.250
(6.35)
19
.870 (22.0) Max
.160
(4.06)
Max
.100 (2.54) Typ .125 (3.17) Min
.800 (20.32)
.325 (8.25)
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