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U C T M EN T ROD E TE P EPLAC nter at E S OL DE D R t Ce m/tsc OB N ppo r MME nical Su tersil.co EC O in Data h or w . November 1994, Rev A NO R t our TecSheetww IL ac ont INTERS c 81-88
(R)
EL4390
FN7164
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 150 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 1300 feedback resistors.
Features
* 80MHz -3dB bandwidth for gains of 1 to 10 * 800V/s 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
Pinout
EL4390 (16-PIN PDIP, SO) TOP VIEW
Ordering Information
PART NUMBER EL4390CN EL4390CM TEMP. RANGE -40C to +85C -40C to +85C PACKAGE 16-Pin PDIP 16-Pin SOL PKG. NO. MDP0031 MDP0027
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright (c) 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 = 25C)
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 AMPLIFIER SECTION (NOT RESTORED) VOS IB+ IBROL RINCMRR PSRR VO ISC ISY Input Offset Voltage IIN+ Input Bias Current IIN- Input Bias Current Transimpedance (Note 1) IN- Resistance Common-Mode Rejection Ratio (Note 2) Power Supply Rejection Ratio (Note 3) Output Voltage Swing; RL = 1k Short-Circuit Current Supply Current (Quiescent)
Supplies at 15V, Load = 1k TEMP MIN TYP MAX UNITS
+25C +25C +25C +25C +25C +25C +25C +25C +25C +25C 50 50 12 45 10 100
2 0.2 10 220 50 56 70 13 70 20
15 5 65
mV A A k dB dB V
100 32
mA mA
RESTORING SECTION VOS, COMP IB+, R IOUT PSRR GOUT ISY, RES VIL, RES VIH, RES IIL, RES IIH, RES 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. Composite Input Offset Voltage (Note 4) Restore IN+ Input Bias Current Restoring Current Available Power Supply Rejection Ratio (Note 3) Conductance Supply Current, Restoring RES Logic Low Threshold RES Logic High Threshold RES Input Current, Logic Low RES Input Current, Logic High +25C +25C +25C +25C +25C +25C +25C +25C +25C +25C 1.4 10 2 50 8 0.2 4 70 8 23 1.0 1.8 2 0.5 10 3 37 1.4 35 5 mV A mA dB mA/V mA V V A A
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EL4390
Closed-Loop AC Electrical Specifications
PARAMETER AMPLIFIER SECTION SR SR BW BW dG d Slew Rate (Note 1) Slew Rate w/ 5V Supplies (Note 2) Bandwidth, -3dB, AV = 1 5V Supplies, -3dB Bandwidth, -0.1dB 5V Supplies, -0.1dB Differential Gain at 3.58MHz at 5V Supplies (Note 3) Differential Phase at 3.58MHz at 5V Supplies (Note 3) 800 550 95 72 20 14 0.02 0.02 0.03 0.06 V/s V/s MHz MHz MHz MHz % % () () DESCRIPTION Supplies at 15V, Load = 150 and 15pF, TA = 25C (Note 1) MIN TYP MAX UNITS
RESTORING SECTION TRE TRD 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 = 820, RG = 200. 3. DC offset from -0.714V to +0.714V, AC amplitude is 286mVP-P, equivalent to 40 ire. Time to Enable Restore Time to Disable Restore 35 35 ns ns
TABLE 1. CHARGE STORAGE CAPACITOR VALUE VS. DROOP AND CHARGING RATES CAP VALUE (NF) 10 22 47 100 220 DROOP IN 60S (MV) 30 13.6 6.4 3.0 1.36 CHARGE IN 2S (MV) 400 182 85 40 18 CHARGE IN 4S (MV) 800 364 170 80 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+ x (Line time - Charge time) / capacitor value and the basic charging formula is: V (charge) = IOUT x Charge time / capacitor value Where IOUT is: IOUT = (Clamp voltage - IN+ voltage) / 120
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EL4390 Typical Performance Curves
Gain Flatness for Various RF VS = 15V, AV = 0dB Gain Flatness for Various RF VS = 5V, AV = 0dB Gain Flatness for Various RF and RG Values VS = 15V, AV = 6dB
Gain Flatness for Various RF and RG Values VS = 5V, AV = 6dB
Phase Shift for AV = 2, RF = RG = 1300
Phase Shift for AV = 2, RF = RG = 1000 at VS = 5V and VS = 15V
Gain Flatness VS = 15V, AV = 14dB, RF/RG as Shown
Gain Flatness VS = 5V, AV = 14dB, RF/RG as Shown
Phase Shift for AV = 5dB, RF = 820, RG = 200, VS = 5V
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EL4390 Typical Performance Curves
Gain Flatness VS = 5V, AV = 20dB, RF/RG as Shown
(Continued)
Gain Flatness VS = 5V, AV = 26dB, RF = 680, RG = 36
Differential Gain at VS = 15V
Differential Phase at VS = 15V
Differential Gain at VS = 5V
Differential Phase at VS = 5V
Frequency Response for Various CLOAD, VS = 15V, RF = RG = 1300
Frequency Response for Various CLOAD, VS = 5V, RF = RG = 1300
Crosstalk, Channel R and B to Channel G, VS = 5V, RF = 1300
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EL4390 Typical Performance Curves
Crosstalk, Channel R and G to Channel B, VS = 5V, RF = 1300
(Continued)
IN+ Input Impedance during HOLD, VS = 5V
IN+ Input Impedance during SAMPLE, VS = 5V
Phase Shift at IN+ Pin during Restore, RS = 75 and 150, VS = 5V
IOUT Restoring vs Clamp, Voltage at VS = 5V
Pulse Response with AV = 2, RF = RG = 1300 at VS = 5V
Output during DC-Restoration, Showing DC Droop RF = RG = 1300, VS = 5V
Output during DC-Restoration, RF = RG = 1300, VS = 5V
Pulse Response with AV = 5, RF = 820 and RG = 200 at VS = 15V
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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- x 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- x 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 60S 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) 10 22 47 100 220 DROOP IN 60S (MV) 30 13.6 6.4 3.0 1.36 CHARGE IN 2S (MV) 400 182 85 40 18 CHARGE IN 4S (MV) 800 364 170 80 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 560k 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.
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EL4390
FIGURE 1.
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EL4390
FIGURE 2.
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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.
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
Layout and Dissipation Considerations
As with all high frequency circuits, the supplies should be bypassed with a 0.1F ceramic capacitor very close to the supply pins, and a 4.7F 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
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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 25C, 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.
For information regarding Intersil Corporation and its products, see www.intersil.com 12

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