DATASHEET

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ECO Technica ww.inter
Data
Sheet
November 1994, Rev A
NO R t o u
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IL or
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t
n
R
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8-INT
1-88
EL4390
®
Triple 80MHz Video Amplifier with DC
Restore
The EL4390 is three wideband
current-mode feedback amplifiers
optimized for video performance, each
with a DC restore amplifier. The DC restore function is
activated by a common TTL/CMOS compatible control signal
while each channel has a separate restore reference.
Each amplifier can drive a load of 150Ω at video signal
levels. The EL4390 operates on supplies as low as ±4V up to
±15V.
Being a current-mode feedback design, the bandwidth stays
relatively constant at approximately 80MHz over the ±1 to
±10 gain range. The EL4390 has been optimized for use with
1300Ω feedback resistors.
Pinout
FN7164
Features
• 80MHz -3dB bandwidth for gains of 1 to 10
• 800V/µs slew rate
• 15MHz bandwidth flat to 0.1dB
• Excellent differential gain and phase
• TTL/CMOS compatible DC restore function
• Available in 16-pin PDIP, 16-pin SOL
Applications
• RGB drivers requiring DC restoration
• RGB multiplexers requiring DC restoration
• RGB building blocks
• Video gain blocks requiring DC restoration
• Sync and color burst processing
Ordering Information
EL4390
(16-PIN PDIP, SO)
TOP VIEW
1
PART
NUMBER
TEMP. RANGE
PACKAGE
PKG. NO.
EL4390CN
-40°C to +85°C
16-Pin PDIP
MDP0031
EL4390CM
-40°C to +85°C
16-Pin SOL
MDP0027
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright © Intersil Americas Inc. 2003. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc.
All other trademarks mentioned are the property of their respective owners.
EL4390
Absolute Maximum Ratings (TA = 25°C)
Supply Voltage between VS+ and GND. . . . . . . . . . . . . . . . . +12.6V
Input Voltage (IN+, IN-, ENABLE, CLAMP) . . . GND -0.3V, VS +0.3V
VS
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . ±18V or 36V
VIN Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±15V or VS
∆VIN Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . .±6V
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests
are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
Open-Loop DC Electrical Specifications
PARAMETER
DESCRIPTION
Supplies at ±15V, Load = 1kΩ
TEMP
MIN
TYP
MAX
UNITS
AMPLIFIER SECTION (NOT RESTORED)
VOS
Input Offset Voltage
+25°C
2
15
mV
IB+
IIN+ Input Bias Current
+25°C
0.2
5
µA
IB-
IIN- Input Bias Current
+25°C
10
65
µA
ROL
Transimpedance (Note 1)
+25°C
RIN-
IN- Resistance
+25°C
CMRR
Common-Mode Rejection Ratio (Note 2)
+25°C
PSRR
Power Supply Rejection Ratio (Note 3)
VO
100
220
kΩ
50
Ω
50
56
dB
+25°C
50
70
dB
Output Voltage Swing; RL = 1kΩ
+25°C
±12
±13
V
ISC
Short-Circuit Current
+25°C
45
70
100
mA
ISY
Supply Current (Quiescent)
+25°C
10
20
32
mA
RESTORING SECTION
VOS, COMP
Composite Input Offset Voltage (Note 4)
+25°C
8
35
mV
IB+, R
Restore IN+ Input Bias Current
+25°C
0.2
5
µA
IOUT
Restoring Current Available
+25°C
2
4
mA
PSRR
Power Supply Rejection Ratio (Note 3)
+25°C
50
70
dB
GOUT
Conductance
+25°C
8
mA/V
ISY, RES
Supply Current, Restoring
+25°C
VIL, RES
RES Logic Low Threshold
+25°C
VIH, RES
RES Logic High Threshold
+25°C
IIL, RES
RES Input Current, Logic Low
+25°C
2
10
µA
IIH, RES
RES Input Current, Logic High
+25°C
0.5
3
µA
NOTES:
1. For current feedback amplifiers, AVOL = ROL/RIN2. VCM = ±10V for VS = ±15V.
3. VOS is measured at VS = ±4.5V and VS = ±16V, both supplies are changed simultaneously.
4. Measured from VCL to amplifier output, while restoring.
2
10
1.4
23
37
mA
1.0
1.4
V
1.8
V
EL4390
Closed-Loop AC Electrical Specifications
PARAMETER
Supplies at ±15V, Load = 150Ω and 15pF, TA = 25°C (Note 1)
DESCRIPTION
MIN
TYP
MAX
UNITS
AMPLIFIER SECTION
SR
Slew Rate (Note 1)
800
V/µs
SR
Slew Rate w/ ±5V Supplies (Note 2)
550
V/µs
BW
Bandwidth, -3dB, AV = 1
±5V Supplies, -3dB
95
72
MHz
MHz
BW
Bandwidth, -0.1dB
±5V Supplies, -0.1dB
20
14
MHz
MHz
dG
Differential Gain at 3.58MHz
at ±5V Supplies (Note 3)
0.02
0.02
%
%
dθ
Differential Phase at 3.58MHz
at ±5V Supplies (Note 3)
0.03
0.06
(°)
(°)
RESTORING SECTION
TRE
Time to Enable Restore
35
ns
TRD
Time to Disable Restore
35
ns
NOTES:
1. Test fixture was designed to minimize capacitance at the IN- input. A “good” fixture should have less than 2pF of stray capacitance to ground at
this very sensitive pin. See application notes for further details.
2. SR is measured at 20% to 80% of 4Vpk-pk square wave, with AV = 5, RF = 820Ω, RG = 200Ω.
3. DC offset from -0.714V to +0.714V, AC amplitude is 286mVP-P, equivalent to 40 ire.
TABLE 1. CHARGE STORAGE CAPACITOR VALUE VS.
DROOP AND CHARGING RATES
CAP VALUE
(NF)
DROOP IN
60µS (MV)
CHARGE IN
2µS (MV)
CHARGE IN
4µS (MV)
10
30
400
800
22
13.6
182
364
47
6.4
85
170
100
3.0
40
80
220
1.36
18
36
These numbers represent the worst case bias current, and
the worst case charging current. Note that to get the full
(2mA+) charging current, the clamp input must have
>250mV of error voltage.
Note that the magnitude of the bias current will decrease as
temperature increases.
The basic droop formula is:
V (droop) = IB+ × (Line time - Charge time) / capacitor value
and the basic charging formula is:
V (charge) = IOUT × Charge time / capacitor value
Where IOUT is:
IOUT = (Clamp voltage - IN+ voltage) / 120
3
EL4390
Typical Performance Curves
Gain Flatness for Various RF
VS = ±15V, AV = 0dB
Gain Flatness
for Various RF and RG Values
VS = ±5V, AV = 6dB
Gain Flatness
VS = ±15V, AV = 14dB,
RF/RG as Shown
4
Gain Flatness for Various RF
VS = ±5V, AV = 0dB
Gain Flatness
for Various RF and RG Values
VS = ±15V, AV = 6dB
Phase Shift for AV = 2,
RF = RG = 1300Ω
Phase Shift for AV = 2,
RF = RG = 1000Ω
at VS = ±5V and VS = ±15V
Gain Flatness
VS = ±5V, AV = 14dB,
RF/RG as Shown
Phase Shift
for AV = 5dB, RF = 820Ω,
RG = 200Ω, VS = ±5V
EL4390
Typical Performance Curves
Gain Flatness
VS = ±5V, AV = 20dB,
RF/RG as Shown
Differential Phase
at VS = ±15V
Frequency Response
for Various CLOAD, VS = ±15V,
RF = RG = 1300Ω
5
(Continued)
Gain Flatness
VS = ±5V, AV = 26dB,
RF = 680Ω, RG = 36Ω
Differential Gain
at VS = ±15V
Differential Gain
at VS = ±5V
Differential Phase
at VS = ±5V
Frequency Response
for Various CLOAD, VS = ±5V,
RF = RG = 1300Ω
Crosstalk,
Channel R and B to Channel G,
VS = ±5V, RF = 1300Ω
EL4390
Typical Performance Curves
(Continued)
Crosstalk,
Channel R and G to Channel B,
VS = ±5V, RF = 1300Ω
IN+ Input Impedance
during HOLD, VS = ±5V
Phase Shift at IN+ Pin
during Restore,
RS = 75Ω and 150Ω, VS = ±5V
IOUT Restoring vs Clamp,
Voltage at VS = ±5V
Output during DC-Restoration,
Showing DC Droop
RF = RG = 1300Ω, VS = ±5V
6
Output during DC-Restoration,
RF = RG = 1300Ω, VS = ±5V
IN+ Input Impedance
during SAMPLE, VS = ±5V
Pulse Response with AV = 2,
RF = RG = 1300Ω at VS = ±5V
Pulse Response with AV = 5,
RF = 820Ω and RG = 200Ω
at VS = ±15V
EL4390
Typical Performance Curves
(Continued)
Maximum Power Dissipation
vs Ambient Temperature—
16-Pin PDIP
Maximum Power Dissipation
vs Ambient Temperature—
16-Pin PDIP
Simplified Schematic of One Channel of EL4390
Applications Information
Circuit Operation
Each channel of the EL4390 contains a current feedback
amplifier and a TTL/CMOS compatible clamp circuit. The
current that the clamp can source or sink into the noninverting input is approximately:
I = (VCLAMP - VIN+) / 120
So, when the non-inverting input is at the same voltage as
the clamp reference, no current will flow, and hence no
charge is added to the capacitor. When there is a difference
in voltage, current will flow, in an attempt to cancel the error
AT THE NON-INVERTING input. The amplifier’s offset
voltage and (IB- × RF) DC errors are not cancelled with this
7
loop. It is purely a method of adding a controlled DC offset to
the signal.
As well as the offset voltage error, which goes up with gain,
and the IB- × RF error which drops with gain, there is also the
IB+ error term. Since the amplifier is capacitively coupled,
this small current is slowly integrated and shows up as a
very slow ramp voltage. Table below shows the output
EL4390
voltage drift in 60µS for various values of coupling capacitor,
all assuming the very worst IB+ current.
TABLE 2. CHARGE STORAGE CAPACITOR VALUE VS.
DROOP AND CHARGING RATES
CAP VALUE
(NF)
DROOP IN
60µS (MV)
CHARGE IN
2µS (MV)
CHARGE IN
4µS (MV)
10
30
400
800
22
13.6
182
364
47
6.4
85
170
100
3.0
40
80
220
1.36
18
36
In normal circuit operation, the picture content will also
cause a slow change in voltage across the capacitor, so at
every back porch time period, these error terms can be
corrected.
When a signal source is being switched, e.g., from two
different surveillance cameras, it is recommended to
synchronize the switching with the vertical blanking period,
and to drive the HOLD pin (pin 6) low, during these lines.
This will ensure that the system has been completely
restored, regardless of the average intensity of the two
pictures.
Application Hints
Figures 1 & 2 shows a three channel DC-restoring system,
suitable for R-G-B or Y-U-V component video, or three
synchronous composite signals.
Figure 1 shows the amplifiers configured for non-inverting
gain, and Figure 2 shows the amplifiers configured for
inverting gains. Note that since the DC-restoring function is
accomplished by clamping the amplifier’s non-inverting
input, during the back porch period, any signal on the noninverting input will be distorted. For this reason, it is
recommended to use the inverting configuration for
composite video, since this avoids the color burst being
altered during the clamp time period.
Since all three amplifiers are monolithic, they run at the
same temperature, and will have very similar input bias
currents. This can be used to advantage, in situations where
the droop voltage needs to be compensated, since a single
trim circuit can be used for all three channels. A 560kΩ or
similar value resistor helps to isolate each signal. See Figure
2. The advantage of compensating for the droop voltage, is
that a smaller capacitor can be used, which allows a larger
level restoration within one line. See Table 1 for values of
capacitor and charge/droop rates.
8
EL4390
FIGURE 1.
9
EL4390
FIGURE 2.
10
EL4390
FIGURE 3.
In Figure 3, one of the three channels is used, together with
a low-offset op-amp, to automatically trim the bias current of
the other two channels. The two remaining channels are
shown in the non-inverting configuration, but could equally
well be set to provide inverting gains. Two DC-restored
channels are typically needed in fader applications. See the
EL4094 and EL4095 for suitable, monolithic video faders.
Layout and Dissipation Considerations
As with all high frequency circuits, the supplies should be
bypassed with a 0.1µF ceramic capacitor very close to the
supply pins, and a 4.7µF tantalum capacitor fairly close, to
handle the high current surges. While a ground plane is
recommended, the amplifier will work well with a “star”
grounding scheme. The pin 3 ground is only used for the
11
internal bias generator and the reference for the TTL
compatible “HOLD” input.
As with all current feedback capacitors, all stray capacitance
to the inverting inputs should be kept as low as possible, to
avoid unwanted peaking at the output. This is especially true
if the value of RF has already been reduced to raise the
bandwidth of the part, while tolerating some peaking. In this
situation, additional capacitance on the inverting input can
lead to an unstable amplifier.
Since there are three amplifiers all in one package, and each
amplifier can sink or source typically more than 70mA, some
care is needed to avoid excessive die temperatures.
Sustained, DC currents, of over 30mA, are not
recommended, due to the limited current handling capability
of the metal traces inside the IC. Also, the short circuit
EL4390
protection can be tripped with currents as low as 45mA,
which is seen as excessive distortion in the output waveform.
As a quick rule of thumb, both the SOL and DIP 16 pin
packages can dissipate about 1.4 watts at 25°C, and with
±15V supplies and a worst case quiescent current of 32mA,
yields 0.96 watts, before any load is driven.
Dissipation of the EL4390 can be reduced by lowering the
supply voltage. Although some performance is degraded at
lower supplies, as seen in the characteristic curves, it is
often found to be a useful compromise. The bandwidth can
be recovered, by reducing the value of RF, and RG as
appropriate.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
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