STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER

S-8540/8541 Series

19

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Precautions

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Install the external capacitors, diode, coil, and other peripheral components as close to the IC as possible,

and make a one-point grounding.

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Characteristics ripple voltage and spike noise occur in IC containing switching regulators. Moreover rush

current flows at the time of a power supply injection. Because these largely depend on the inductor, the

capacitor and impedance of power supply used, fully check them using an actually mounted model.

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If the input voltage is high and output current is low, pulses with a low duty ratio may appear, and then the

0% duty ratio continues for several clocks. In this case the operation changes to the pseudo pulse

frequency modulation (PFM) mode, but the ripple voltage hardly increases.

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If the input power supply voltage is lower than 1.0 V, the IC operation is unstable and the external switch

may be turned on.

If input power supply voltage is 10.0 V or higher, the circuit operation is unstable and the IC may be

damaged.

The input voltage must be in the standard range (2.5 to 10.0 V).

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In choosing the components, make sure that overcurrent will not surpass the allowable dissipation of the

switching transistor and the inductor.

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Make sure that dissipation of the switching transistor will not surpass the allowable power dissipation of the

package (especially at high temperature).

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Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in

electrostatic protection circuit.

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SII Semiconductor Corporation shall bear no responsibility for any patent infringement by a product that

includes an IC manufactured by SII Semiconductor Corporation in relation to the method of using the IC in

that product, the product specifications, or the destination country.