Philips 27PS60S321 manual Safe-Restart Mode, Standby

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Safe-Restart Mode

This mode is introduced to prevent the componentsfrom being destroyed during eventual system fault conditions. Itis also used for the Burst mode. The Safe-Restart mode will be enteredif it is triggered by one of the following functions:

zOver voltageprotection,

zShort winding protection,

zMaximum ‘on time’ protection,

zV CC reachingUVLO level (fold back during overload),

zDetecting a pulse for Burst mode,

zOver temperature protection.

When entering the Safe-Restart mode, the output driveris immediately disabled and latched. The V CC winding will not chargethe V CC capacitoranymore and the V CC voltagewill drop until UVLO is reached. To recharge the V CC capacitor, the internalcurrent source (I (restart)(VCC) ) will be switched ‘on’ to initiate a new start-upsequence as described before. This Safe-Restart mode will persistuntil the controller detects no faults or burst triggers.

Standby

The set goes to Standby in the following cases:

zAfter pressingthe ‘standby’ key on the remote control.

zWhen the set is in protection mode.

In Standby, the power supply works in ‘burstmode’.

Burst mode can be used to reduce the power consumption below1 W at stand-by. During this mode, the controller is active (generatinggate pulses) for only a short time and for a longer time inactivewaiting for the next burst cycle.

In the active period the energy is transferred to thesecondary and stored in the buffer capacitor C STAB in front of the linear stabilizer(see Figure below). During the inactive period, the load (e.g. microprocessor)discharges this capacitor. In this mode, the controller makes useof the Safe-Restart mode.

7/8/2004