The ISL59830A is a revolutionary device that allows single-supply operation of video amplifiers. The device runs off a single 3.3V supply and generates the desired negative internal voltage. This enables DC precision coupling to play video on a 75Ω double-ended circuit. Because the buffer has an integrated 6dB gain, the only external components require a 75Ω termination resistor and a small capacitor. The input reference voltage can be used to shift the analog video level by an amount equal to the reference voltage (typically 0.6V).

Note: Intersil lead-free + annealed products feature a special lead-free material set; molding compound/mold join material and 100% matte tinplate finish, RoHS compliant and compatible with SnPb and lead-free soldering operations. Intersil's lead-free products are classified as MSLs that meet or exceed the lead-free requirements for temperature IPC/JEDEC J Standard-020 during lead-free peak reflow soldering.

feature

Triple Single Supply Buffer

Single power supply +3.3V power supply

No output DC blocking capacitors required

2 output buffers with fixed gain

output tri-stable

enable/disable function

Charge pump power off function

50MHz 0.1dB bandwidth

200MHz-3dB bandwidth

Lead-free plus annealed (RoHS compliant) available

application

driving video

Absolute Maximum Ratings (TA=+25 degrees)

Supply voltage between VCC, US and GND5V

VCC+0.3V, V-0.3V

Voltage between VIN and VIN... 2 volts between VIN and VIN

Maximum Continuous Output Current...Maximum Continuous Output Current 30mA

Operating temperature, operating temperature, operating temperature, operating temperature. -40-C to +85-C

max temp... max temp... max temp + 150°C

Storage Temperature Storage Temperature Storage Temperature -65-C to +150-C

Lead temperature Lead temperature Lead temperature + 260 degrees Celsius

Power consumption power consumption power consumption see curve

WARNING: Stresses in excess of the Absolute Maximum Ratings may cause permanent damage to the device. This is a pressure rating and operation

Installation under the above or any other conditions stated in the operating section of this specification is not implied.

IMPORTANT: Guaranteed all parameters with min/max specs. Typical values are for reference only. Unless otherwise stated, all tests are pulsed at the specified temperature, thus: TJ=TC=TA

AC Electrical Specifications VCC=DVCC=+3.3V, REF=GND, TA=+25°C, RL=150Ω, unless otherwise specified

DC Electrical Specifications VCC=DVCC=+3.3V, REF=GND, TA=+25°C, RL=150Ω, unless otherwise specified.

Operation and Application Notes

Theory of Operation The ISL59830A is a triple high bandwidth, high speed, low power, rail-to-rail voltage feedback amplifier with a charge pump that provides a negative rail with no additional power supply. Designed for 0V to 3.3V, the ISL59830A requires no separate power supply with a charge pump at 1.6V underground to generate a 4.9V range on a single 3.3V supply on a bottom rail. This show is perfect for NTSC video and its negative sync pulse. The amplifier ISL59830A is a transistor over 20GHz in isolation high 4ghzpnps and NPN speed 5V dual CMOS process - ideal for low distortion, low power requirements and high frequency circuits. While the ISL59830A uses some standard voltage-mode feedback topology, there are many non-standard analog characteristics that provide excellent bandwidth operation and output drive capability. The input signal initially passes through the folded cascode primarily through the fixed input and gain stages. The collector of each input device is directly viewed through a resistor and biased with a very stable DC power supply. The bandwidth limitation of effective Miller capacitance is greatly reduced since the current collector voltage "locks to stabilize". The signal then passes through a second fully implemented differential gain stage and finally through a proprietary common emitter output stage for enhanced rail-to-rail output performance. The result is a very stable, low distortion, low power and high frequency amplifier near rail-to-rail driving of moderate capacitive loads.

Input and Output Range The three amplifier channels have an input common-mode voltage range from 0.15V to 100mV under the bottom rail of the positive supply, the VS+ pin (note: the bottom rail is powered by the negative half of the charge pump to establish the positive supply). As the input signal is moved within the specified range, the output signal will have increasingly higher levels of harmonic distortion. Of course, as the load resistance gets smaller, the current drive capability of the device will be challenged, and it can be reduced on each rail. For example, a load resistor of 1kΩ when loaded with a 150Ω resistor limits the output swing to a rail of 300mV. Amplifier Output Impedance In order to achieve near rail-to-rail performance, the output stage ISL59830A uses a transistor configuration in the common emitter, typically producing higher output impedance than standard emitter follower output stages. The ISL59830A and local feedback reduce the output impedance to below 2Ω at low frequencies. However, since the device is open-loop gain, the output impedance increases with frequency while the open-loop gain decreases with frequency. The inductive effect of this output impedance in the ISL59830A with its proprietary output stage topology maintains a low output impedance range over a wide frequency range and enables it to drive relatively heavy capacitive loads easily and efficiently (see Figure 10).

oil filling pump

The ISL59830A oil-charged pump provides an underground 1.65V supply when operating from a 0V to 3.3V supply. The charge pump is internally regulated to half the positive supply potential. This internal polyphase charge pump is driven by a 160MHz differential loop driving a series of inverters and charge storage oscillator circuits. Each series inverter charges and parallels the adjacent charging circuit with immediately preceding the block. The overall effect is a continuous discharge and a very low ripple of about 10 mV suitable for an amplifier supplying the negative rail to -1.65 volts. There are two ways to reduce output power supply noise.

A 120Ω ferrite bead in series between VCC and DVCC further reduces ripple.

Add a 20pF capacitor to ground between the piggyback 75Ω resistors (see ISL59830A+DC Recovery Solution Schematic on page 10).

The operating frequency of the system is high enough that the associated charge pump noise far exceeds standard video bandwidth requirements. However, proper bypassing must be disciplined, all with power or priming pumps must be properly bypassed. See "Board Layout" in the "Power Supply Bypass and Printed Circuits" section in this section. The VREF pin applies a voltage to the VREF pin, usually the resistance of a voltage amplifier on the ground side of the gain, resulting in an output signal. Apply 100 to the Vref pin A millivolt voltage will apply 100mV DC level shift to the output signal. Charge the pump to provide enough bottom space to accommodate the shifted signal. Note: The VREF input is a 3 amp common point negative input resistor. Any common resistor on the VREF input will be connected with other The terminals share the sensed voltage amps, so using a resistive source to get the offset will cause all amps and the amp + input gain to change. The offset on the VREF pin must be low impedance to prevent gain errors and crosstalk. A transistor emitter follower should Works like an NPN MMBT3904 with the transmitter connected to the VREF pin and 1k pull down to V-1µF cap bypass ground collector to V+ and base to V offset source. Diodes can be placed in series with the tank if better tempco if needed Use ground. The 499W resistor can be used with the collector to prevent damage when testing. See block diagram on page 9

V-shaped pin

The V-pin is the output pin of the priming pump. A voltmeter applied to this pin will show the charge pump. This pin does not affect the section. This pin can be used as an additional voltage source. Remember that the output of this pin is powered by the internal charge pump and fully regulated and must be bypassed properly. We recommend using 0.1µF ceramic capacitors placed close to the pins and connected to the ground plane of the board. Input, Output, and Supply Voltage Ranges The ISL59830A is designed for single-supply operation from 0V to 3.3V. The need for a split power supply has been ruled out by a charge pump capable of generating sub-1.6V bottom rail to ground for the 4.9V range on a single 3.3V supply. This performance is ideal for NTSC video sync pulses. Video Performance For good video performance, an amplifier is required to maintain the same output impedance and the same frequency and phase response to changes in DC level at the output. This is especially difficult when driving standard video loads because changes in the output current change the DC level. Special circuitry has been incorporated into the ISL59830A to reduce output impedance variation with current output. This results in differential gain and differential phase specifications of 0.06% and 0.1° while driving 150Ω with a gain of +2. Driving higher impedance loads will result in similar or better differential gain and differential phase performance.

The ISL59830A internally generates the negative rail which is very suitable for NTSC video and its accompaniment negative sync signal; it is easy to be used by the ISL59830A. No additional power supply is required.

A YPbPr signal from a DVD player requiring three channels with very tightly controlled amplifier gain accuracy presents no difficulty for the ISL59830A. Especially the sync on the standard coded Y channel, which is a negative going signal; easily handled by the ISL59830A without the need to place the negative 1/2 positive supply when the ISL59830A produces a negative rail. Also Pb and Pr are bipolar analog signals, and the video signal is negative running; again easily handled by the ISL59830A

Drive capacitive loads and cables

The ISL59830A, internally compensated to drive a 75Ω cable, will drive a 10pF load in parallel with 1kΩ, less than 5dB to peak. If less peaking is required, a small series resistance, usually between 5Ω and 50Ω, can be used with the output. This will sacrifice a little closed loop gain reduction. When used as a cable driver, double-terminated performances are recommended for no reflections. For these applications, a resistor at the output of a back-end series amplifier will allow the amplifier to be driven with and allow a wide range of capacitances. However, other applications may have high capacitive loads and do not require back-end resistors. Also, having a small series resistor at the output helps reduce peaking. The ISL59830A is a triple amplifier designed to drive three channels; simply treat each channel as a separate channel as described in this section. DC Restore Restores the DC reference of the signal when the ISL59830A is AC coupled. This is done through capacitive "AC" coupling and the input of the device. Refer to Application Circuits for reference DC reduction solutions. Disable/Shutdown The ISL59830A can be disabled and its outputs placed in a high impedance state. The off time is about 25 ns and the power on time is about 200ns. The amplifier's supply current is typically reduced to 0.9mA when disabled, effectively eliminating power dissipation. The power drop of this amplifier can be controlled by standard TTL or CMOS signal levels on the EN and PD pins. Application logic signals are relative to the VS-pin. Float the EN and PD pins or apply a signal 0.8V below VS-will to enable the amplifier. When the signal at the EN pin is higher than VS-2V. The amplifier must be disabled when the charge pump is disabled (PD pin high). The EN and PD pins should be tied together to allow the amplifier and charge pump to be enabled/disabled simultaneously.

output drive capability

The ISL59830A has no internal short circuit protection circuit. The 80mA source short-circuit current output terminal is connected between the half-way 150mA sinking tracks with 10Ω resistance. If the output is shorted indefinitely, power dissipation can easily increase that part will be destroyed. The maximum reliability is that if the output current never exceeds ±40 mA, the electromigration limit of the process is that exceeding this value will damage the part. This limitation is determined by the design of the internal metal interconnects. Power dissipation with the ISL59830A's high output drive capability may exceed +150°C absolute maximum junction temperature at a certain load current. Therefore, it is important to calculate the maximum junction temperature for applications that determine load conditions or require modification of the package type to ensure the amplifier is in a safe operating area. The maximum power consumption allowed in the package is determined by:

TJMAX = maximum junction temperature

TAMAX = maximum ambient temperature

ΘJA = thermal resistance of the package

The maximum power dissipation actually generated by the integrated circuit is the total quiescent supply current times the total power supply voltage plus the power generated by the load in the integrated circuit, or: for purchases:

VS = supply voltage

ISMAX = maximum quiescent supply current

VOUT = maximum output voltage applied

RLOAD = ground load resistance

ILOAD = load current

i=Number of output channels

By setting the two PDMAX equations equal, we can account for the effects of output current and load on overheating of the device.

Power Bypass and Printed Circuits

board layout

A stripline design technique is recommended for the input output signal trace. As with any high frequency device, a good PCB layout is a must for optimization. Lead lengths should be as short as possible. The power supply pins must be bypassed completely to reduce the risk of oscillation. For normal single-supply operation, where the VS-pin is connected to the ground plane, a single 4.7µF tantalum capacitor in parallel with a 0.1µF ceramic capacitor from VS+ to GND is sufficient. Same capacitor if using separate internal supply. In this case, the VS pin becomes the negative rail. For good AC performance, parasitic capacitance should be kept to a minimum. The use of wirewound resistors should be avoided due to the additional series inductance. Sockets should also be avoided if possible. Sockets add parasitic inductance and capacitance that can result in compromised performance. Minimizing parasitic capacitance at the inverting input pin of the amplifier is also very important.