SDA5275P Datasheet, PDF (20/30 Pages) Siemens Semiconductor Group – ICs for Consumer Electronics MEGATEXT and MEGATEXT PLUS ICs

SDA 5273 / 75
SDA 5273-2 / 75-2
Characteristics (cont’d)
T_A = 0 to 70 °C
Parameter
Symbol
Limit Values
Unit Test Condition
min. typ. max.
Reset/Chip Initialization
A power-on reset or a reset pulse at pin RES lead to a hardware reset and a software initialization
of registers and internal DRAM. During initialization bus transfers are not allowed.
At / after power-on a reset pulse at pin RES is necessary. RES may return to 0 after the supply
voltage reached its lower limit for chip function (4.7 V). This may be achieved by a capacitor C
between RES and V_DD and by a resistor R between RES and V_SS. The dimensions of R and C
depend on the worst case rise time of V_DD.
Initialization time after power- t_INIT
on or falling edge of RES
25 ms V_DD greater 4.7 V
If the supply voltage drops below V_{DD min}, the IC has to be reset by pin RES.
Pulse width RES
100
ns
High level at pin RES causes chip reset.
In rare cases, the IC may remain in a permanent reset state after power up, depending on the
applicational context. After power up, the software should check proper operation. In case the
Megatext does not react properly, power supply should be switched off for at least 3 s. After that,
power supply can be switched on again.
Other Items
Horizontal frequency pull-in
range of CVBS-PLL:
Horizontal frequency pull-in
range of display-PLL:
15 15.625 16.2 kHz PAL
20.48 MHz crystal
15.2 15.748 16.3 kHz NTSC
20.48 MHz crystal
15 15.625 16.2 kHz
20.48 MHz crystal
Semiconductor Group
20
1997-09-01