Datasheet

LMH0030

www.ti.com

SNLS219G –JANUARY 2006–REVISED APRIL 2013

APPLICATION INFORMATION

Complete details for the SD130ASM evaluation PCB are available on TI’s WEB site. This circuit demonstrates

the capabilities of the LMH0030 and allows its evaluation in a native configuration. An assembled demonstration

board kit, part number SD130EVK, complete with operating instructions, drawing package and list of materials is

available. Contact the Interface Products Group or the Serial Digital Video and Interface Applications Group for

ordering information. Complete circuit board layouts, schematics and other information for the SD130EVK are

also available on TI's WEB site in the application information for this device. For latest product details and

availability information, please see: www.ti.com/appinfo/interface.

PCB LAYOUT AND POWER SYSTEM BYPASS RECOMMENDATIONS

Circuit board layout and stack-up for the LMH0030 should be designed to provide noise-free power to the device.

Good layout practice also will separate high frequency or high level inputs and outputs to minimize unwanted

stray noise pickup, feedback and interference. Power system performance may be greatly improved by using thin

dielectrics (4 to 10 mils) for power/ground sandwiches. This increases the intrinsic capacitance of the PCB power

system which improves power supply filtering, especially at high frequencies, and makes the value and

placement of external bypass capacitors less critical. External bypass capacitors should include both RF ceramic

and tantalum electrolytic types. RF capacitors may use values in the range 0.01 µF to 0.1 µF. Tantalum

capacitors may be in the range 2.2 µF to 10 µF. Voltage rating for tantalum capacitors should be at least 5X the

power supply voltage being used. It is recommended practice to use two vias at each power pin of the LMH0030

as well as all RF bypass capacitor terminals. Dual vias reduce the interconnect inductance by up to half, thereby

reducing interconnect inductance and extending the effective frequency range of the bypass components.

The outer layers of the PCB may be flooded with additional V

(ground) plane. These planes will improve

shielding and isolation as well as increase the intrinsic capacitance of the power supply plane system. Naturally,

to be effective, these planes must be tied to the V

power supply plane at frequent intervals with vias. Frequent

via placement also improves signal integrity on signal transmission lines by providing short paths for image

currents which reduces signal distortion. The planes should be pulled back from all transmission lines and

component mounting pads a distance equal to the width of the widest transmission line or the thickness of the

dielectric separating the transmission line from the internal power or ground plane(s) whichever is greater. Doing

so minimizes effects on transmission line impedances and reduces unwanted parasitic capacitances at

component mounting pads.

The LMH0030 uses two power supply voltages, 2.5 and 3.3 volts. These supplies connect to the device through

seven sets of independent power input pins. The function and system supplied through these is given in the Pin

Description Table. The power supply voltages normally share a common 0 volt or ground return system. Either a

split plane or separate power planes can be used to supply the positive voltages to the device.

In especially noisy power supply environments, such as is often the case when using switching power supplies,

separate filtering may be used at the LMH0030's PLL analog, PLL digital and serial output driver power pins. The

LMH0030 was designed for this situation. The digital section, PLL and output driver power supply feeds are

independent. See the Pin Description Table and the Connection Diagram for details. Supply filtering may take the

form of L-section or pi-section, L-C filters in series with these V

inputs. Such filters are available in a single

package from several manufacturers. Despite being independent feeds, all device power supplies should be

applied simultaneously as from a common source.

Product Folder Links: LMH0030