lm5027asqx National Semiconductor Corporation, lm5027asqx Datasheet - Page 22

• Manufacturer Part Number: lm5027asqx
• Description: Lm5027a Voltage Mode Active Clamp Controller
• Manufacturer: National Semiconductor Corporation

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Current Sense
The CS pin receives an input signal representative of the
transformer primary current, either from a current sense
transformer or from a resistor in series with the source of the
primary switch, as shown in
cases the sensed current creates a ramping voltage across
R
edge transients. The filtering components RSENSE, RF and
CF should be physically as close to the LM5027A as possible.
SENSE
, and the RF/CF filter suppresses noise and leading
Figure 14
and
Figure
FIGURE 14. Transformer Current Sense
15. In both
22
The current sense components must be scaled for 0.5V at the
CS pin when an over-current condition exists.
If the voltage on the CS pin reaches 0.5V, the present cycle
will be immediately terminated. If the over-load event contin-
ues and the RES pin reaches 1V, the soft-start capacitor is
discharged and the LM5027A will go through an auto re-start
(Hiccup Mode). The Hiccup Mode time is set by the capacitor
on the RES pin.
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