Working principle, IC pin details, Power supply circuit diagram - Philips 25 inch color TV DVD combo 25HT3312
The Hercules generates this signal. This line is logic “low” (0 V) under normal operation and in semi-Standby of the TV, and is “high” (3.3 V) during Standby.
Power - down signal
The AUX SMPS generates this signal. It is logic “high” (3 .3 V) under normal operation of the TV and goes “low” (0 V) when the AC power (or Mains) input voltage supply goes below 70 V_ac.
B (Hercules port)
This port is used to switch the AUX SMPS output V_aux “On/Off”. This is required for DVD and iDTV (for future extensions).
Startup Sequence
When the set is connected to the AC power, the rectified line voltage (via winding 4-5 of L5531 connected to pin 14 of IC7531) will start the internal voltage source to charge the V_cc capacitor (C2532). The IC starts to switch as soon as the V_cc reaches the V_cc start level of 9.5 V. This supply is automatically taken over by winding 1-2, as soon as the V_cc is high enough, and the internal supply source will stop (for high efficiency switching).
Pinning
overview TEA1523
As C2532 of IC7531 is charged, it will also start to charge the V_cc capacitor (C2511) of IC7511. Via resistor R3519 and C2511, the TEA1506 starts to switch as soon as the V_cc voltage reaches the V_cc start level of is about 11 V. The V_cc voltage is automatically taken over by the main transformer L5512 (winding 2-3) when the V_cc is high enough (when this voltage is even higher than the voltage on C2511, there is no current flow from C2532 to C2511 due to diode D6512)
Pinning overview TEA1506
Standby Mode
In this mode, IC7511 (TEA1506) will be totally disabled. So there is no voltage on the main transformer output. But IC7531 (TEA1523) will still work and will provide the necessary output voltages (6V > 5V, 3.3V, 3V > 1.8V) to the Hercules (IC7200)
SMPS Circuit diagram
External power supply
PSU voltage overview
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