Samsung P, Service Manual

Page: 19 / 104

Circuit Operation Description
Samsung Electronics 5-5
1) Over voltage Protection
SMPS has an over voltage detection circuit as well as a circuit which keeps a constant level of voltage.
It is designed so that when an Over Voltage occurs in any part it does not affect another output part.
SMPS cuts off Over Voltage in latch mode. The following tagle gives te Over Voltage protection
specifications.
Table2. Over voltage Protection.
Parameter
VS(85V)
VA(75V)
D6V
D3.3V
Min
100 ~
94 ~
8.2 ~
4.7 ~
Unit
V
V
V
V
2) Short Circuit and Over current Protection.
Short-circuit of the output terminal is defined as an output impedance that is less than 300mohm.
For a given SMPS, when a VS output is short-circuited, the SMPS stops operation. Even if a short-circuit
occurs between the main output and the STD_5V, the SMPS does not fail. When the short-circuit is cleared,
it will operate normally again. Even if a short_circuit occurs when the SMPS is operating within the range
presented in Chapter 3, it will not cause a malfunction to the parts or the PCB patterns.
The following table gives Over Current protection specifications.
Table3. Over Current Protection.
Parameter
VS(85V)
VA(75V)
12V
6V
D3.3V
Min
~
~
~
~
~
Unit
A
A
A
A
A