ADV7127

–9–

REV. 0

PIN FUNCTION DESCRIPTIONS

Pin

Mnemonic

Function

CLOCK

Clock Input (TTL Compatible). The rising edge of CLOCK latches the R0–R9, G0–G9, B0–B9,

SYNC and

BLANK pixel and control inputs. It is typically the pixel clock rate of the video system. CLOCK should be driven

by a dedicated TTL buffer.

D0–D9

Data Inputs (TTL Compatible). Data is latched on the rising edge of CLOCK. D0 is the least significant data bit.

Unused data inputs should be connected to either the regular PCB power or ground plane.

Current Output. This high impedance current source is capable of directly driving a doubly terminated 75

Ω

coaxial cable.

full-scale video signal. Note that the IRE relationships are maintained, regardless of the full-scale output current.

× V

Ω)

COMP

Compensation Pin. This is a compensation pin for the internal reference amplifier. A 0.1

µF ceramic capacitor

Voltage Reference Input. An external 1.23 V voltage reference must be connected to this pin. The use of an exter-

nal resistor divider network is not recommended. A 0.1

µF decoupling ceramic capacitor should be connected

Analog Power Supply (5 V

± 5%). All V

GND

Ground. All GND pins must be connected.

Differential Current Output. Capable of directly driving a doubly terminated 75

Ω load. If not required, this out-

put should be tied to ground.

PSAVE

Power Save Control Pin. The part is put into standby mode when

PSAVE is low. The internal voltage reference

circuit is still active on the TSSOP in this case.

PDOWN

Power-Down Control Pin (24-Lead TSSOP Only). The ADV7127 completely powers down, including the voltage

reference circuit, when

PDOWN is low.

TERMINOLOGY

Color Video (RGB)

This usually refers to the technique of combining the three

primary colors of red, green and blue to produce color pictures

within the usual spectrum. In RGB monitors, three DACs are

required, one for each color.

Gray Scale

The discrete levels of video signal between reference black and

reference white levels. A 10-bit DAC contains 1024 different

levels, while an 8-bit DAC contains 256.

Raster Scan

The most basic method of sweeping a CRT one line at a time to

generate and display images.

Reference Black Level

The maximum negative polarity amplitude of the video signal.

Reference White Level

The maximum positive polarity amplitude of the video signal.

Video Signal

That portion of the composite video signal which varies in gray

scale levels between reference white and reference black. Also

referred to as the picture signal, this is the portion that may be

visually observed.