ST5R00 Просмотр технического описания (PDF) - STMicroelectronics

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ST5R00

MICROPOWER VFM STEP-UP DC/DC CONVERTER

STMicroelectronics 

ST5R00 SERIES

DIODE SELECTION

A Schottky diode with an high switching speed and a very low Forward Voltage (VF) is needed. Higher VF

may cause lost power as heat in the diode, with a decrease of the Efficiency. Moreover, since the Output

Voltage pin is also used as the device Supply Voltage, the Start-up Voltage (see related plots) is strictly

due to the diode Forward Voltage at the rated Forward Current. A good diode choice is a STPS1L30A.

INPUT/OUTPUT CAPACITORS SELECTION

The Output Ripple Voltage, as well as the Efficiency, is strictly related to the behavior of these elements.

The output ripple voltage is the product of the peak inductor current and the output capacitor Equivalent

Series Resistance (ESR). Best performances are obtained with good high frequency characteristics

capacitors and low ESR. The best compromise for the value of the Output Capacitance is 47µF Tantalum

Capacitor, Lower values may cause higher Output Ripple Voltage and lower Efficiency without

compromising the functionality of the device.

An Input Capacitor is required to compensate, if present, the series impedance between the Supply

Voltage Source and the Input Voltage of the Application.

A value of 4.7µF is enough to guarantee stability for distances less than 2". It could be necessary

(depending on VIN, VOUT, IOUT values) to proportionally increase the input capacitor value up to 100µA for

major distances.

In any case we suggest to connect both capacitors, CIN and COUT, as close as possible to the device pins.

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