lm5045sqx National Semiconductor Corporation, lm5045sqx Datasheet - Page 24

• Manufacturer Part Number: lm5045sqx
• Description: Full-bridge Pwm Controller With Integrated Mosfet Drivers
• Manufacturer: National Semiconductor Corporation

www.national.com
CURRENT SENSE
The CS pin receives an input signal representative of its
transformer’s primary current, either from a current sense
transformer or from a resistor located at the junction of source
pin of the primary switches, as shown in Figure 18 and Figure
19 respectively. In both the cases, the filter components R
and C
the ground connection from the current sense transformer, or
R
pin. Please refer to the layout section for more layout tips.
SENSE
F
should be located as close to the IC as possible, and
should be a dedicated trace to the appropriate GND
FIGURE 18. Transformer Current Sense
FIGURE 19. Resistor Current Sense
F
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The current sense components must provide a signal >
710mV at the CS pin during an over-load event. Once the
voltage on the CS pin crosses the current limit threshold, the
current sense comparator terminates the PWM pulse and
starts to charge the RES pin. Depending on the configuration
of the RES pin, the LM5045 will eventually initiate a hiccup
mode restart or be in continuous current limit.
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