TDA8777_3

© Koninklijke Philips Electronics N.V. 2005. All rights reserved.

Preliminary data sheet

Rev. 03 — 15 August 2005

6 of 18

Philips Semiconductors

TDA8777

Triple 10-bit video DAC, up to 330 MHz sample frequency

An external reference resistor must be connected between pin RSET and analog ground.

This resistor sets the reference current which determines the analog output level, and is

specified to be 560

Ω. This value allows a 1 V (p-p) output (video plus sync) into a 37.5 Ω

load, such as a double-terminated 75

Ω coaxial cable.

8.2 Blanking and sync pulse insertion

The video signal (see Figure 3) is comprised of the following three parts:

amplitude = 700 mV (p-p)

video line and the start of the next video line; sync nominal amplitude = 300 mV; sync

is added to the video signal output via the SYNC input (active LOW)

is allocated either side of the sync pulse; the blank level is equal to the video black

level; blanking is added to the video signal output via the BLANK input (active LOW).

The values of SYNC and BLANK are latched on the rising edge of the clock signal. When

no sync and no blank are applied, the DAC can be used continuously. This is the so-called

generic mode.

Because the signal delay in the DAC is 1.5 times the clock period, the sync and blank are

also delayed by 1.5 times the clock period.

9.

Limiting values

Fig 3.

Video signal sync pulse and blanking period

mle291

sync pulse

blanking period

video information

0.7 V

0.3 V

Table 4:

Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol

Parameter

Conditions

Min

Max

Unit

analog supply voltage

−0.5

+6.5

V

voltage on digital input pins

−0.5

+5.5

V

storage temperature

−55

+150

°C

ambient temperature

0

70

°C

junction temperature

−40

+125

°C