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STV9211

Functional description

2

FUNCTIONAL DESCRIPTION

2.1

RGB input, clamping function

The three RGB inputs have to be supplied with a video signal (maximum peak-to-peak value = 1V)

through coupling capacitors (100 nF typ.).

The RGB inputs include a clamping function using the input serial capacitor as “memory capacitor”.

To avoid the discharge of this capacitor during the line (due to leakage current), the input voltage is

referenced to the ground.

This clamping function is gated by the BPCP pulse (Black Porch Clamping Pulse) which is internally

generated (see

(see

Note 1: When BPCP is synchronized by BLK, the leading edge of the BLK must be selected to get a proper

synchronization.

Figure 3: BPCP selection of synchronization edge

- Synchronization:

HS or BLK signal (Register 8, bit0)

- Polarity:

Positive or negative (Automatic detection) when synchronized by HS

Positive or negative ( programmed via Register 9, bit 0) when

synchronized by BLK - see

Note 1

- Edge:

Trailing or Leading (Register 8, bit1)

- Width:

From 0.33µs to 1.33µs (Register 8, bit2 and bit3)

- Direct BPCP:

If the application provides the BPCP, one can program the direct

connection between Pin 19 and the internal BPCP (Register 8, bit4)

Synchronization

source

Edge selection

BPCP generation

HS

(R8, bit 0=0)

Trailing

(R8, bit 1=0)

HS (Pin 19)

Internal BPCP

Leading

(R8, bit 1=1)

HS (Pin 19)

Internal BPCP

BLK

(R8, bit 0=1)

Leading

(R8, bit 1=0)

BLK (Pin 20)

Internal BPCP

HS

(R8, bit 4=1)

_

HS (Pin 19)

Internal BPCP =HS