ILA8395N View Datasheet(PDF) - Integral Corp.

Part Name

Description

Manufacturer

ILA8395N

SECAM decoder

Integral Corp. 

ILA8395N

FUNCTIONAL DESCRIPTION

The ILA8395N is a self-calibrating SECAM decoder designed for use with a baseband delay circuit. During

frame retrace a 4.433619 MHz reference frequency is used to calibrate the filters and the demodulator. The reference

frequency should be very stable during this period.

The Cloche filter is a gyrator-capacitor type filter the resonance frequency of which is controlled during the

calibration period and offset during scan; this ensures the correct frequency during calibration. The demodulator is a

Phase-Locked Loop (PLL) type demodulator which uses the frequency reference and the bandgap reference to force the

PLL to the required demodulation characteristic.

The low frequency de-emphasis is matched to the PLL and is controlled by the tuning voltage of the PLL. A

digital identification circuit scans the incoming signal for SECAM (only line-identification is implemented). The

identification circuit needs to communicate with the ILA8362ANS to guarantee that the output signal from the decoder

is only available when no PAL signal has been identified. If a SECAM signal is decoded a request for colour-on is

transmitted to pin 1 (current is sunk). If the signal request is granted (i.e. pin 1 is HIGH therefore no PAL) the colour

difference outputs ((BY) and (RY)) from the ILA8362 are high impedance and the output signals from the ILA8395N

are switched ON.

If no SECAM signal is decoded during a two-frame period the demodulator will be initialized before another

attempt is made also during a two-frame period. The CD outputs will be blanked or high-impedance depending on the

logic level at pin 1.

A two-level sandcastle pulse generates the required blanking periods and, also, clocks the digital identification

pulse on the falling edge of the burst gate pulse. To enable the calibration period to be defined the vertical retrace is

discriminated from the horizontal retrace, this is achieved by measuring the width of the blanking period.

APPLICATION INFORMATION

The leakage current at pin 8 should be well below 20 nA to meet the specification of the black levels (C8 = 220

nF).

The leakage current at pin 7 should be well below 60 nA to meet the specification of the Cloche resonance

frequency (C7 = 100 nF).

The capacitors C7 and C8 should be connected to the ground pin as close as possible to the package. If not, this

can result in a black level error for both channels.

TEST INFORMATION

The performance of the Cloche filter can be measured at pin 2. The use of a FET-probe is advised for low

capacitive loading.

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