THAT1420 ETC [List of Unclassifed Manufacturers], THAT1420 Datasheet - Page 5

• Manufacturer Part Number: THAT1420
• Description: Balanced Line Drivers
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Rev. 4/24/01
Preliminary Information
1420/1430 are relatively straightforward.
solid ground reference, stiff voltage supplies, and ad-
equate supply bypassing are all that is required to
achieve excellent performance out of both ICs. Both
devices are stable into any capacitive load, and the
maximum capacitance is limited only by slew rate
and frequency response considerations.
lation, the line driver’s 50W sense resistors can be
lumped into a single 100W resistor. The correct ca-
ble
inter-conductor capacitance and the two conduc-
tor-to-shield capacitances. Unfortunately, some man-
ufacturers
capacitance and the capacitance of one conductor to
the other while connected to the shield, and some ex-
traction may be required.
shielded, twisted pair with 30pF/ft of inter-conductor
capacitance and 25pF/ft of conductor to shield capac-
Circuit
For the purposes of the frequency response calcu-
As an example, one manufacturer supplies a
4. Copyright ã 1991 Rane Corporation
100n
100n
In
capacitance
C4
C5
implementations
only
4
3
In
Gnd
Vcc
Vee
to
VEE
VCC
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
specify
Sens+
Sens-
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
use
Out-
Out+
U1
THAT1420
is
8
the
1
using
the
Figure 4. Basic THAT 1420 applications circuit
inter-conductor
sum
the
A quiet,
of
Applications
THAT
the
itance. The corner frequency of the THAT 1420/1430
driving 500 ft of this cable will be
One must also consider the slew rate limitations
posed by excessive cable and other capacitances. We
know that
and that
Rane Corporation has published a document titled
RaneNote 126
ments for a balanced line driver, including a)
stablility into reactive loads, b) output voltage swing
of at least ±11 volts peak (+20dBu), and c) reliabil-
ity. This document also suggests a reasonable rule
by which to calculate the output current require-
ments at 20kHz. The author concludes that the ac-
dV
i
dt
f
C
=
=
=
C
2
3
V
2
dV
dt
´ ´
Peak
In-
In+
p
100
Vee
4
Vcc
VCC
´
VEE
, which specifies some of the require-
W
2p
´
500 30
Ref
´
f
(
Out
U2
THAT1243 or equiv.
pF
C6
100n
C7
100n
1
ft
6
+
25
pF
Out
ft
+
25
pF
ft
)
»
40
kHz
Page 5