OPA361

SBOS334A − SEPTEMBER 2005 − REVISED JANUARY 2006

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11

Video

DAC

1.8V DAC

0.5V V

REF

2−Pole

Filter

Shutdown

Control

+

75

Ω

1.8V

Pull−Up

10k

Ω

100k

4k

Ω

(see note 1)

G = 5.2V/V

75

Ω

TV Detect

TV Detect

GPIO

(1) Closed when enabled during normal operation; open when shut down.

(2) Protects GPIO against overvoltage conditions during active video transmission.

(3) GPIO must be able to generate interrupt.

OMAP2420

OPA361

TWL92230

500

Ω

Regulator V

AUX

2.5V or 2.8V

10mV

R

SET

+In

Out

V+

GND

Enable

Figure 10. Using TV-Detect Signal to Disable/Enable the OPA361

Disabling the OPA361 also disconnects the internal

feedback resistors’ path to GND, and therefore there is no

current flowing from the logic supply through the pull-up

resistor to GND if no video load is connected; this helps to

conserve battery life. The typical leakage when the output

is pulled high and OPA361 is disabled is only about 300pA.

The

following

functionality

can

be

achieved

by

implementing TV-detection:

periodically.

is disconnected.

Proper implementation allows to significantly simplify the

user interface.

For more information, see Application Report SBOA109,

OPA361 and TV Detection, available for download at

www.ti.com.