VOUT(MAX)=nominal output voltage plus maximum output voltage tolerance IOUT(MAX) =maximum output current plus inductor ripple current RDS(ON)P(MAX)=maximum P-channel switch RDS(ON)P RDC(L) =DC resistance of the inductor If VIN6.3V, the OVP will sleep the chip.
2009.4
WuXi Delicacy Science and Technology Co.,Ltd
5/7
DST6156
APPLICATION INFORMATION
Output Voltage Setting(only for DST6156 ADJ) In the adjustable version only, the external resister sets the output voltage according to the following equation:
VOUT 0.6V (1
R1 ) R2
Inductor Selection For high efficiencies, the inductor should have a low dc resistance to minimize conduction losses. Especially at high switching frequencies the core material has a higher impact on efficiency. When using small chip inductors, the efficiency is reduced mainly due to higher inductor core losses. This needs to be considered when selecting the appropriate inductor. The inductor value determines the inductor ripple current. The larger the inductor value, the smaller the inductor ripple current and the lower the conduction losses of the converter. Conversely, larger inductor values cause a slower load transient response. To avoid saturation of the inductor, the DC current should be rated at least for the maximum output current of the converter plus half the inductor ripple current that is calculated as
L
1 VOUT VOUT (1 ) fosc IL VIN
ILMAX IOUTMAX
IL 2
IL = peak-to-peak inductor ripple current ILmax = maximum inductor current Input Capacitor Sellection Because DST6156 have a pulsating input current, a low ESR input capacitor is required. This results in the best input voltage filtering, minimizing the interference with other circuits caused by high input voltage spikes. Also, the input capacitor must be sufficiently large to stabilize the input voltage during heavy load transients. For good input voltage filtering, usually a 4.7μF input capacitor is sufficient. It can be increased without any limit for better input-voltage filtering. Ceramic capacitors show better performance because of the low ESR value, and they are less sensitive against voltage transients and spikes compared to tantalum capacitors. Place the input capacitor as close as possible to the VIN pin and GND pin of the device for best performance. Output Capacitor Sellection The output capacitor is required to keep the output voltage ripple small and to ensure regulation stability. For excellent output voltage filtering and loop stability, a 10μF output capacitor is adaptable. The cap must have low impedance at switching frequency. Ceramic capacitors are recommended due to their low ESR and high ripple current. The output ripple voltage is determined by:

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