ML6429CS-1 查看數據表（PDF） - Micro Linear Corporation

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ML6429CS-1

75W Quad Video Cable Drivers and Filters with Switchable Inputs

Micro Linear Corporation 

ML6429

FUNCTIONAL DESCRIPTION

The ML6429 is a quad monolithic continuous time analog

video filter designed for reconstructing signals from four

video D/A sources. The ML6429 is intended for use in AC

coupled input and output applications.

The filters approximate a 4th-order Butterworth

characteristic with an optimization toward low overshoot

and flat group delay. All outputs are capable of driving

2VP-P into AC coupled 150W video loads, with up to 35pF

of load capacitance at the output pin. Likewise, they are

capable of driving a 75W load at 1VP-P.

All channels are clamped during sync to establish the

appropriate output voltage swing range. Thus the input

coupling capacitors do not behave according to the

conventional RC time constant. Clamping for all channels

settles within 10ms of a change in video sources.

Input coupling capacitors of 0.1µF are reccommended for

all channels. During sync, a feedback error amplifier

sources/sinks current to restore the DC level. The net result

is that the average input current is zero. Any change in the

input coupling capacitors value will linearly affect the

clamp response times.

The RGB channels have no pulldown current sources and

are essentially tilt-free. The CV channel's inputs sink less

than 1µA during active video, resulting in a tilt of less than

1mV for a 220 µF. Up to 1000µF recommended to reude

tilt for TV applications.

SWAP MULTIPLEXER CONTROL

Output pins CVOUT1/YOUTA and CVOUT2/YOUTB are each

independently selectable between three input sources

(CVINF, and CVINUA, CVINUB) depending on the digital

inputs SWAP CVF, SWAP CVU, and A/B MUX. This allows

the two outputs to remain independent and pass straight

through, to remain independent but swapped, or for both

outputs to have the same signal sourcing from either CVINF

or CVINFA, CVINUB (See Table 1). If SWAP CVF is forced

to logic low, then CVOUT2/YOUTB sources from CVINUA/

Y2, CVINUB/Y3. If SWAP CVU is logic low, CVOUT1/

YOUTA outputs video from the CVINUA, CVINUB input. If

SWAP CVF is logic high, CVOUT2/YOUTB outputs from

CVINF/Y1 input. If SWAP CVU is high, CVOUT1/YOUTA

outputs from CVINUA/Y2 or CVINUB/Y3. Both SWAP CVF

and SWAP CVU will pull low if they are not driven.

The ML6429 is robust and stable under all stated load and

input conditions. Bypassing both VCC pins directly to

ground ensures this performance. Two ML6429’s can be

connected in a master-slave sync configuration. When

using this configuration, only the “master” ML6429 is

required to have a signal with embedded sync present on

the CVINUA, CVINUB input. In the absence of sync on the

CVINUA or CVINUB input of the “slave” ML6429, the

“slave” IC will have its SYNC IN input connected to the

SYNC OUT output of the “master” ML6429.

SYNCIN AND SYNCOUT PINS

Each ML6429 has two sync detectors which control the

DC restore functions. The filtered channel has its own

detector, which controls the DC restore function during

the horizontal sync period of the CVINF/Y1 input. The

other sync detector controls the DC restore functions for

the filtered channels based upon the composite or luma

input at the CVINUA/Y2 or CVINUB/Y3 pins.

Required Setup: A composite or luma or green signal

must be present on CVINUA/Y2 or CVINUB/Y3 inputs to

provide necessary sync signals to other channels

(R,G,B,Y,C). Otherwise, sync must be provided at the

SYNCIN pin. For RGB applications, the green channel

with sync can be used as an input to CVINUA/Y2 or

CVINUB/Y3.

The SYNCOUT pin outputs a logic high when it detects

the horizontal sync of either the CVINUA/Y2 or CVINUB/Y3

input (note that one input is selected by the A/B MUX pin).

The SYNCIN pin is an input for an external H-sync logic

signal to enable or disable the internal DC restore loop for

the filtered channels. When SYNCIN is logic high, the DC

restore function is enabled.

For normal operation, the SYNCOUT pin is connected to

the SYNCIN pin (see Figure 4). If the CVINUdoes not have

an embedded sync, an external sync can be applied on

the SYNCIN pin. In master-slave configurations, the

SYNCOUT of a ML6429 master can be used as the

SYNCIN of a ML6429 slave.

VIDEO I/O DESCRIPTION

Each input is driven by either a low impedance source or

the output of a 75W terminated line. The input is required

to be AC coupled via a 0.1µF coupling capacitor which

gives a nominal clamping time of 10ms. All outputs are

capable of driving an AC coupled 150W load at 2VP-P or

1VP-P into a 75W load. At the output pin, up to 35pF of

load capacitance can be driven without stability or slew

issues. A 220µF AC coupling capacitor is recommended at

the output to reduce power consumption.

ANALOG MULTIPLEXER CONTROL

The four filter channels each have two input multiplexers

which are paired to select between two four-channel

video sources (i.e., composite video plus RGB component

video).

If A/B MUX is forced to logic high, it will select Bank<A>

of video inputs (CVINUA/Y2, RINA/Y4, GINA/Y6, BINA/C1)

to be enabled. If A/B MUX is logic low, then Bank<B> of

video inputs (CVINUB/Y3, RINB/Y5,GINB/Y7, BINB/C2) will

be selected. If the A/B MUX is open, it will pull to logic

high.

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