Philips 27PS60S321 manual In- And Output Selection, Power Supply Control

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recognition is donevia a voltage divider.

The front LED (6691) is connected to an output controlline of the microprocessor (pin 5). It is activated to provide theuser information about whether or not the set is working correctly (e.g.,responding to the remote control, normal operation (USA only) orfault condition)

In- And Output Selection

For the control of the input and output selections,there are three lines:

zSTATUS1 This signal providesinformationrmation to the microprocessor on whether a video signalis available on the SCART1 AV input and output port (only for Europe). Thissignal is not connected in NAFTA sets.

zSTATUS2 Thissignal provides informationrmation to the microprocessor on whethera video signal is available on the SCART2 AV input and output port(only for Europe). For sets with an SVHS input it provides the additional informationrmationif a Y/C or CVBS source is present. The presence of anexternal Y/C source makes this line ‘high’ whilea CVBS source makes the line ‘low’.

zSEL-MAIN-FRNT-RRThisis the source select control signal from the microprocessor. Thiscontrol line is under user control or can be activated by the othertwo control lines.

Power Supply Control

The microprocessor part is supplied with 3.3V and 3.9 V both derived from the ‘MainAux’ voltagevia a 3V3 stabilizer (7560) and a diode.

Two signals are used to control the power supply:

zStdby_con This signalis generated by the microprocessor when over-current takes placeat the ‘MainAux’ line. This is done to enablethe power supply into standby burst mode, and to enable this modeduring a protection. This signal is ‘low’ undernormal operation conditions and goes to ‘high’ (3.3V) under ‘standby’ and ‘fault’ conditions.

zPOWER_DOWN Thissignal is generated by the power supply. Under normal operatingconditions this signal is ‘high’ (3.3 V). During ‘standby’ mode,this signal is a pulse train of approx. 10 Hz and a ‘high’ durationof 5 ms. It is used to give information to the UOC about the fault conditionin the Audio amplifier supply circuit. This information is generatedby sensing the current on the ‘MainAux’ line (usingvoltage drop across R3564 to trigger Q7562). This signal goes ‘low’ whenthe DC-current on the ‘MainAux’ line exceeds 1.6- 2.0 A. It is also used to give an early warning to the UOC abouta power failure. Then the information is used to mute the soundamplifier to prevent a switch off noise and to solve the switch-offspot.

7/8/2004