TDA4841PS Datasheet, PDF (13/60 Pages) NXP Semiconductors – I2C-bus autosync deflection controller for PC monitors

Philips Semiconductors
I²C-bus autosync deflection controller for
PC monitors
Product specification
TDA4841PS
Table 3 Activation of protection mode
ACTIVATION
Low supply voltage at
pin 10
Power dip, below 8.1 V
X-ray protection XRAY
(pin 2) triggered
HPLL2 (pin 30) externally
pulled to ground
RESET
increase supply voltage,
reload registers,
soft start via I²C-bus
reload registers,
soft start via I²C-bus or via
supply voltage
reload registers,
soft start via I²C-bus
release pin 30
When the protection mode is active, several pins of the
TDA4841PS are forced into a defined state:
HDRV (horizontal driver output) is floating
BDRV (B+ control driver output) is floating
HUNLOCK (indicates, that the frequency-to-voltage
converter is out of lock) is floating (HIGH via external
pull-up resistor)
CLBL provides a continuous blanking signal
VOUT1 and VOUT2 (vertical outputs) are floating
The capacitor at HPLL2 is discharged.
If the soft start procedure is activated via the I²C-bus, all of
these actions will be performed in a well defined sequence
(see Figs 22 and 23).
Power dip recognition
In standby mode the I²C-bus will only answer with an
acknowledge when data is sent to the control register 1AH.
This register contains the standby and soft start control bit.
If the I²C-bus master transmits data to another register, an
acknowledge is given after the chip address and the
subaddress; an acknowledge is not given after the data.
This indicates that data can be stored into normal registers
only in soft start mode.
If the supply voltage drops below 8.1 V the deflection
controller leaves normal operation and changes to standby
mode. The microcontroller can check this state by sending
data into a register with the subaddress 0XH.
The acknowledge will only be given on the data if the IC is
active.
Due to this behaviour the start-up of the TDA4841PS is
defined as follows: the first data that is transferred to the
deflection controller must be sent to the control register
with subaddress 1AH. Any other subaddress will not lead
to an acknowledge. This is a limitation in checking the
I²C-busses of the monitor during start-up.
1999 Oct 25
13