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XR-2247 Datasheet Preview

XR-2247 Datasheet

Floppy Disk Write Amplifier

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XR·2247/2247A
Floppy Disk Write Amplifier
GENERAL DESCRIPTION
FUNCTIONAL BLOCK DIAGRAM
The XR-2247/2247A is a write amplifier designed to pro-
vide the complete interface between write data signals
and tunnel-erase magnetic heads. Although primarily
intended for floppy disk drive systems, the XR-22471
2247A can also be used in other magnetic media sys-
tems such as tape drives. To minimize external part
count for dual head systems, complete head switching
is does internally with emitter-coupled PNP transistors
in the XR-2247 and diodes (which offer improved broad-
band noise characteristics) in the XR-2247A. Write and
erase currents are each externally programmable with
a single resistor. Also included is circuitry for inner
track write current compensation. To prevent false
write current outputs during power-on, an inhibit input
has been provided. Erase turn-on and turn-off times are
each externally programmable.
The XR-2247/2247A, available in a 22-Pin DIP, operates
from a single power supply and provides TIL compati-
ble inputs.
Vee
eTa
TOOFF
GND
HS
fGND
r--_----4 20 ~
HEAD 1
~
~
~OUT
~
HEADO
~
IRWS
FEATURES
Fully Programmable Write and Erase Currents
Fully Programmable Erase Turn-onlTum-off Times
Internal Head Switching for Dual Head Drives
Single Supply Operation
Inner Track Write Current Compensation
Inhibit Input
TIL Compatible Inputs
Low External Parts Count
APPLICATIONS
Floppy Disk Drives
SinglelDual Head Systems
Magnetic Tape Write Amplifier
ABSOLUTE MAXIMUM RATINGS
Power Supply Voltage (Pin 1)
16 V dc
Input Voltage (all digital inputs) - 0.2V to + 16 V dc
Reference Current (Pin 4)
10 rnA dc
Output Current (Pins 2, 10, 12,22)
100 mA dc
Storage Temperature
- 55°C to + 150°C
Operating Junction Temperature
150°C
Power Dissipation
750 mW
Derate Above 25°C
6.5 mW/oC
ORDERING INFORMATION
Part Number
XR-2247CN
XR-2247CP
XR-2247ACN
XR-2247ACP
Package
Ceramic
Plastic
Ceramic
Plastic
Operating Temperature
O°C to + 70°C
O°C to +70°C
O°C to + 70°C
O°C to + 70°C
SYSTEM DESCRIPTION
The XR-2247/2247A accepts a serial binary data
stream input. With the write mode selected, negative
transitions of this input signal will alternately provide
write current to each half of the head. The XR-22471
2247A provides two sets of current outputs for dual
head drives, with the head select (HS) control determin-
ing which is active. The write current is externally pro-
grammed with a resistor between the internal voltage
reference and the current setting input. Two high-
current open-collector outputs provide the erase coil
drive. Turn-on and turn-off delay circuitry is provided for
these outputs, with the delay externally programmed.
An inhibit input (INH) is provided to disable the outputs
to prevent false writing during power-on. With the read
mode selected, internal head switching channels the
proper head to the read outputs.
4-6




Exar

XR-2247 Datasheet Preview

XR-2247 Datasheet

Floppy Disk Write Amplifier

No Preview Available !

XR·2247/2247A
ELECTRICAL CHARACTERISTICS
Test Conditions: TA = 25°C, VCC = 12V, Rref = 10 kO, unless otherwise specified.
SYMBOL
PARAMETERS
ICC Power Supply Current
VCC Power Supply Range
DIGITAL INPUT VOLTAGE
V,H High Level Voltage
V,L Low Level Voltage
DIGITAL INPUT CURRENTS
IIH High Level Current
',L Low Level Current
CTO or CT1 OUTPUTS
VCTH Output High Voltage
VCTL Output Low Voltage
EO or E1 OUTPUTS
IOL Output High Leakage
VOEL Output Low Voltage
TD ON Erase Turn-on Delay
TD OFF Erase Turn-off Delay
CURRENT SOURCE
Vref Reference - Pin 4
Vmir
'WRL
Vcomp
'WR
'WRS
AIWA
Iref Input Voltage - Pin 13
Write Current Off Leakage -
Pins 15, 16, 19,20
Current Sink Compliance -
Pins 15, 16, 19,20
Write Current wlo IAWS-
Pins 15,16, 19,20
Write Current with 'RWS -
Pins 15, 16, 19,20
Difference in Write Current
READ OUTPUT
eno Differential Noise Voltage at Read
Output -
2247
2247A
Note 1: Difference = 1(lplN 15,16 - 'piN 19,20)1
MIN TYP MAX UNIT
CONDITIONS
- 13 20 rnA VCC = 9V to 16V
9 12 16 V
2.0 - -
- - 0.8
V
V
- 0.1 4.0 p.A V, = 2.4V
- 15 100 p.A
9.5 10.2 -
- 0.1 0.2
V lout = 100 rnA
V lout = 1 rnA
- 0.01 20 p.A VCC = 16V
- 1.0 1.5 V 'out = 100 rnA
0.45 0.5 0.55 mS RD1 = 4.55 KO, CD1 = 0.1 p.F
0.9 1.0 1.1 mS RD2 = 9.54 KO, CD2 = 0.1 p.F
8.0 8.5 9.0 V Iref = 1 rnA
7.8 8.2 8.8 V Iref = 10 rnA
0.65 0.80 0.95 V Iref = 1 rnA
- 0.03 15 p.A
7 - 12 V
3.7 4.1 4.5 rnA 'RWS = Low
5.1 5.7 6.3
- - 40
rnA 'RWS = High
p.A 'RWS = Low (Note 1)
-
-
4
1
- p.Vrms 8W = 10 Hz to 1.0 MHz
- p.Vrms 18 = 200 p.A
4-7


Part Number XR-2247
Description Floppy Disk Write Amplifier
Maker Exar
Total Page 7 Pages
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