SDA 9380 - B21
Preliminary Data Sheet
System description
within 85ms to its final value. The high time is kept constant. The normal operating pulse ratio H/L is
either 45/55 or 40/60 (selectable by I²C). A watch dog function limits an increasing of the HD period
to max. +10%.
2
The implemented Black Switch-Off behaviour is defined by two I C bits (BSO1, BSO0). When
enabled the signal at BSOIN (e.g. the supply voltage of the line output stage) is watched. If its level
does not come up to a defined threshold Black Swich-Off is started (see 11.2). At first the RGB out-
puts are switched to continuous blanking immediately and the vertical output signals are changed to
about 115..120% overscan. After a delay of 42 lines the picture tube capacitance is discharged with
a current of some mA. From now the vertical overscan rate is calculated depending on the actual
2
voltage at BSOIN to get the desired deflection angle. Three relations are selectable by I C. After the
voltage at BSOIN is dropped down to about 20% of its initial value the output HD and the overscan
calculation may stop.
The protection circuit watches an EHT reference and the saw-tooth of the vertical output stage. If
the EHT succeeds a defined threshold or if the V-deflection fails (refer to 11.5) the related bit is set in
the status byte and the output PROTON goes High. The output HD is deactivated (H-level) immedi-
ately independent of the selected Black Switch-Off function.
HPROT:
input V < V2
continuous blanking
HD disabled
i
V > V1
i
V2 ≤=V < V1
operating range
i
VPROT:
vertical saw-tooth voltage
V < V1 in first half of V-period
i
or V > V2 in second half : HD disabled
i
The pin SCP delivers the composite blanking signal SCP. It contains burst (V ), H-blanking HBL
b
(V
) and selectable V-blanking (control bit SSC). The phase and width of the H-blanking period
HBL
2
can be varied by I C-Bus. For the timing following settings are possible :
BD = 1
: T = 0
BL
BD = 0, BSE = 0 (default value)
BD = 0, BSE = 1(alignment range)
: T
: T
: T
= t (H-flyback time)
HBL
HBL
DBL
f
= (4 * H_blanking-time + 1) / CLL
= (H_shift + 4 * H_blanking_phase
- 2*H_blanking_time + 45) / CLL
SSC = 0
SSC = 1
: T = T
during V-blanking period
BL
VBL
: T is always T
BL
HBL
Micronas
5-8
2001-01-29
MICRONAS [ MICRONAS ]
