LM5010 Datasheet, PDF (16/19 Pages) National Semiconductor (TI) – High Voltage 1A Step Down Switching Regulator

Applications Information (Continued)
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FIGURE 15. Efficiency vs V_IN
Circuit of Figure 14
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FIGURE 17. Output Voltage Ripple vs V_IN
Circuit of Figure 14
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FIGURE 16. Efficiency vs Load Current and V_IN
Circuit of Figure 14
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FIGURE 18. Frequency vs V_IN
Circuit of Figure 14
INCREASING THE CURRENT LIMIT THRESHOLD
The current limit threshold is nominally 1.25A, with a mini-
mum guaranteed value of 1.0A. If, at maximum load current,
the lower peak of the inductor current (I_PK- in Figure 13)
exceeds 1.0A, resistor R_CL must be added between S_GND
and I_SEN to increase the current limit threshold to equal or
exceed that lower peak current. This resistor diverts some of
the recirculating current from the internal sense resistor so
that a higher current level is needed to switch the internal
current limit comparator. I_PK- is calculated from:
www.national.com
(11)
where I_O(max) is the maximum load current, and I_OR(min) is
the minimum ripple current calculated using Equation 10.
R_CL is calculated from:
16