LM2524D, LM3524D

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SNVS766E – JUNE 2009 – REVISED MAY 2013

This holds the output of the error amplifier initially low thus reducing the duty-cycle to a minimum. Without the

slow start circuit the inductor may saturate at turn-on because it has to supply high peak currents to charge the

output capacitor from 0V. It should also be noted that this circuit has no supply rejection. By adding a reference

voltage at the non-inverting input to the error amplifier, see Figure 31, the input voltage variations are rejected.

The LM3524D can also be used in inductorless switching regulators. Figure 32 shows a polarity inverter which if

connected to Figure 30 provides a

−15V unregulated output.

L1 = > 25 turns No. 24 wire on Ferroxcube No. K300502 Toroid core.

Figure 30. 15V, 0.5A Step-Up Switching Regulator

Figure 31. Replacing R3/R4 Divider in Figure 30 with Reference Circuit Improves Line Regulation

Figure 32. Polarity Inverter Provides Auxiliary

−15V Unregulated Output from Circuit of Figure 30

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Product Folder Links: LM2524D LM3524D