4
Application Information
Relevant Application Notes
The following Application Notes pertain to the HFA1115:
AN9653-Use and Application of Output Limiting
Amplifiers
AN9752-Sync Stripper and Sync Inserter for
Composite Video
These publications may be obtained from Intersil’s web site
(http://www.intersil.com) or via our AnswerFax system.
HFA1115 Advantages
The HFA1115 features a novel design which allows the user
to select from three closed loop gains, without any external
components. The result is a more flexible product, fewer part
types in inventory, and more efficient use of board space.
Implementing a gain of 2, cable driver with this IC eliminates
the two gain setting resistors, which frees up board space for
termination resistors.
Like most newer high performance amplifiers, the HFA1115
is a current feedback amplifier (CFA). CFAs offer high
bandwidth and slew rate at low supply currents, but can be
difficult to use because of their sensitivity to feedback
capacitance and parasitics on the inverting input (summing
node). The HFA1115 eliminates these concerns by bringing
the gain setting resistors on-chip. This yields the optimum
placement and value of the feedback resistor, while
minimizing feedback and summing node parasitics. Because
there is no access to the summing node, the PCB parasitics
do not impact performance at gains of +2 or -1 (see “Unity
Gain Considerations” for discussion of parasitic impact on
unity gain performance).
Slew Rate
(V
OUT
= 5V
P-P
, A
V
= +2)
+SR
B
25
-
1265
-
V/
μ
s
-SR (Note 5)
B
25
-
870
-
V/
μ
s
Settling Time
(V
OUT
= +2V to 0V step, Note 4)
To 0.1%
B
25
-
23
-
ns
To 0.05%
B
25
-
33
-
ns
To 0.02%
B
25
-
45
-
ns
VIDEO CHARACTERISTICS
Differential Gain
f = 3.58MHz, A
V
= +2,
R
L
= 150
B
25
-
0.02
-
%
Differential Phase
f = 3.58MHz, A
V
= +2,
R
L
= 150
B
25
-
0.03
-
Degrees
OUTPUT LIMITING CHARACTERISTICS
A
V
= +2, V
H
= +1V, V
L
= -1V, Unless Otherwise Specified
Limit Accuracy (Note 4)
V
IN
=
±
1.6V, A
V
= -1
A
Full
-125
-70
125
mV
Overdrive Recovery Time (Note 4)
V
IN
=
±
1V
B
25
-
0.8
-
ns
Negative Limit Range
B
25
-5.0 to +2.5
V
Positive Limit Range
B
25
-2.5 to +5.0
V
Limit Input Bias Current
A
Full
-
85
200
μ
A
Limit Input Bandwidth
C
25
-
100
-
MHz
POWER SUPPLY CHARACTERISTICS
Power Supply Range
C
25
4.5
-
5.5
±
V
Power Supply Current (Note 4)
A
25
6.6
6.9
7.1
mA
A
Full
-
7.1
7.3
mA
NOTE:
3. Test Level: A. Production Tested; B. Typical or Guaranteed Limit Based on Characterization; C. Design Typical for Information Only.
4. See Typical Performance Curves for more information.
5. Slew rates are asymmetrical if the output swings below GND (e.g., a bipolar signal). Positive unipolar output signals have symmetric positive and
negative slew rates comparable to the +SR specification. See the “Application Information” section, and the pulse response graphs for details.
Electrical Specifications
V
SUPPLY
=
±
5V, A
V
= +1, R
L
= 100
, Unless Otherwise Specified
(Continued)
PARAMETER
TEST
CONDITIONS
(NOTE 3)
TEST
LEVEL
TEMP.
(
o
C)
MIN
TYP
MAX
UNITS
HFA1115