THS8134, THS8134A, THS8134B

TRIPLE 8-BIT, 80 MSPS VIDEO D/A CONVERTER

WITH TRI-LEVEL SYNC GENERATION

SLVS205D – MAY 1999 – REVISED MARCH 2000

5

POST OFFICE BOX 655303

functional description

device configuration

Input data to the device can be supplied from a 3x8b GBR/YPbPr input port. If the device is configured to take

data from all three channels, the data is clocked in at each rising edge of CLK. All three DACs operate at the

full clock speed of CLK.

In the case of 4:2:2 sampled data (for YPbPr) the device can be fed over either a 2x8 bit or 1x8 bit multiplexed

input port. An internal demultiplexer will route input samples to the appropriate DAC: Y at the rate of CLK, Pb

and Pr each at the rate of one-half CLK.

According to ITU-BT.656, the sample sequence is Pb-Y-Pr over a 1x8 bit interface (Y-port). The sample

sequence starts at the first rising edge of CLK after BLANK has been taken high (inactive). In this case the

frequency of CLK is two times the Y conversion speed and four times the conversion speed of both Pr and Pb.

With a 2x8 bit input interface, both the Y-port and the Pr-port are sampled on every CLK rising edge. The Pr-port

carries the sample sequence Pb-Pr. The sample sequence starts at the first rising edge of CLK after BLANK

has been taken high (inactive). In this case the frequency of CLK is equal to the conversion speed of Y and 2x

the conversion speed of both Pr and Pb.

The device’s operation mode is set by the M1 and M2 mode selection terminals, according to Table 1. The

operation mode also determines the blanking level, as explained below in the sync/blanking generation

sections.

Table 1. THS8134 Configuration

M1

M2_INT

CONFIGURATION

DESCRIPTION

L

L

GBR

3x8b–4:4:4

GBR mode 4:4:4. Data clocked in on each rising edge of CLK from G, B, and R input channels. For the

definition of the analog output levels during blanking, see note 1.

L

H

YPbPr

3x8b–4:4:4

YPbPr mode 4:4:4. Data clocked in on each rising edge of CLK from Y, Pb and Pr input channels. For

the definition of the analog output levels during blanking, see note 1.

H

L

YPbPr

2x8b–4:2:2

YPbPr mode 4:2:2 2x8 bit. Data clocked in on each rising edge of CLK from Y & Pr input channels. A

sample sequence of Pb–Pr–... should be applied to the Pr port. At the first rising edge of CLK after

BLANK is taken high, Pb should be present on this port. For the definition of the analog output levels

during blanking, see note 1.

H

H

YPbPr

1x8b–4:2:2

YPbPr mode 4:2:2 1x8 bit (ITU-BT.656 compliant). Data clocked in on each rising edge of CLK from Y

input channel. For the definition of the analog output levels during blanking, see note 1.

NOTE 1: In all device versions, the blanking level on the AGY channel output corresponds to input code 0 of the DAC.

to the 128 input code of the DAC, when sync is inserted on all three channels (INS3_INT=H), and to the 0 input code of the DAC,

when sync is only inserted on the Y channel (INS3_INT=L).

the DAC irrespective if sync is inserted on all three channels (INS3_INT=H), or if sync is inserted only on the Y channel

(INS3_INT=L).