TDA4857 datasheet(35/56 Pages) PHILIPS

35 / 56 page

2000 Jan 31

Philips Semiconductors

Product speciﬁcation

I2C-bus autosync deﬂection controller for

PC monitors

TDA4857PS

Protection and standby mode

Soft-down sequence:

• Start the sequence by setting control bit SOFTST = 0

• BDRV duty cycle decreases

• HDRV duty cycle decreases.

Protection mode:

• Pins HDRV and BDRV are floating

• Continuous blanking at pin CLBL is active

• Pin HUNLOCK is floating

• PLL1 and PLL2 are disabled

• Register contents are kept in internal memory.

Protection mode can be left by 3 ways:

1. Entering standby mode by setting control

bit SOFTST = 0 and control bit STDBY = 1

2. Starting the soft-start sequence by setting control

bit SOFTST = 1 (bit STDBY = don’t care);

see L3 of Fig.18 for continuation

3. Decreasing the supply voltage below 8.1 V.

Standby mode:

• Set control bit STDBY = 1

• Driver outputs are floating (same as protection mode)

• Supply current is 9 mA

• Only the I2C-bus and protection circuits are operative

• Contents of all registers except the value of bit STDBY

and bit SOFTST are lost

• See L2 of Fig.18 for continuation.

MBK382

Standby mode (XXXX XX01)

STDBY = 1

SOFTST = 0

all other register contents are random

Soft-down sequence (XXXX XX00)

STDBY = 0

SOFTST = 0

L3 (1)

yes

SOFTST = 1?

yes

L2 (1)

Protection mode (XXXX XX00)

STDBY = 0

SOFTST = 0

registers are set

STDBY = 1?

8CH

0DH

00H

A P

8CH

0DH

01H

A P

Fig.19 I2C-bus flow for protection and standby

mode.

(1) See Fig.18.

TDA4857 Datasheet(PDF) 35 Page - NXP Semiconductors

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