NR263S Calculation Tool

Runing a Calculation

1. In the Calculation Conditions pane, move the slider to set a numerical value in each field.
− Move the slider to enter or adjust a numerical value in each text box.
− To enter a numecial value directly, click or tap (hereafter “click”) in the field.
− When using a keyboard, click to select the slider thumb, and then use arrow keys (left and right) on your keyboard to move the slider.
2. To run a calculation, click the Calculate button.
− To run a new calculation after you made any changes to the values entered, click the Calculate button again.
− If the tool displays an error calculation result after you click the Calculate button, see “Troubleshooting” below.

Reset Button

1. Resets all the values entered in the Calculation Conditions pane.
2. Resets all the positions of the slider thumbs in the Calculation Conditions pane to their default settings.
3. Makes no change to the values in the Calculation Results pane.

Troubleshooting

1. SYMPTOM: " NaN " is displayed in the Calculation Results pane.
− Either one or more fields in the Calculation Conditions pane are left blank.
− Any of the user-entered values contains numerals or characters other than half-width digits or a half-width period ( . ).
− Any of the user-entered values contains a half-width period ( . ) at an invalid position.
Examples: “ .3.4 ”, “ .2. ”, “ 0.6. ”

The Basics Explained

Basic Circuit Connection

Description of circuit symbols in Basic Circuit Connection

• C_IN ： Input Smoothing Capacitor
• C_OUT ： Output Smoothing Capacitor
• C_SS ： Soft-Start Timing Capacitor
• C_BS ： Power Supply Capacitor for High Side Driver ( Default Value : 0.1µF )
• R_EN1 ： Enable Terminal Setting Resistor ( Default Value : 100kΩ )
• Inductor : Inductance L Value

Inductance L Value Calculation Procedure

1. Enter the wished inductor ripple current ⊿I_L value into the text box of ⊿I_L setting .
2. Click the Calculate button and calculate inductance L value.
3. Please refer to the inductor manufacturer's catalog and select parts with close values.
4. Enter the selected inductance L value into the text box of Inductance L Value Setting.
5. Click the Calculate Button and recalculate ⊿I_L according to the selected inductance L value.

Setting Criterion of Inductor Ripple Current ⊿I_L

Calculation of Pulse-Skip Frequency Fskip

The Pulse-Skip as "Light Load High Efficiency Mode" is a Energy Saving Function installed in the NR263S. It can reduce the number of switching per unit time in the light load condition and reduce power consumption. When the inductance L value is smaller, the Pulse-Skip Frequency Fskip rises higher.

1. Entering of load current I_O at stand-by load

A value of "Stand-by Load Current I_O Setting at Pulse-Skip-Operation" is not maximum load condition when you use. Please use only the stand-by load current value.

2. Entering of Inductor Peak Current IL_P at Pulse-Skip Operation

The inductor peak current IL_P during pulse skipping has dependency on the user-selected inductance L value and the input voltage V_IN. The Pulse-Skip Frequency Fskip can be calculated by the equation described in the datasheet, but you must enter the IL_P value as an indispensable condition. As for the IL_P, please refer to following the reference characteristic chart. Pick up IL_P value from the condition of input voltage V_IN and the condition of user-selected inductance L value, and enter IL_P value into the text box of "Inductor Peak Current IL_P Setting in Pulse-Skip-Operation".

In this tool, the Pulse-Skip Frequency Fskip calculation is only an approximate estimation as the criterion. Please be aware that it is not a guaranteed value.

Supplementary matter

1. The entered target efficiency η value is used to estimate the input current I_in approximatly. It is necessary when you estimate the load current of the transformer secondary winding.
2. Regarding the setting of the target output ripple voltage, please enter the value how do you want to suppress the output ripple voltage magnitude ? (Unit : mV peak to peak)
3. In the calculation result, the ESR requirement value and ripple current of the output smoothing capacitor C_OUT are calculated by the user selected inductance L value.
4. The internal loss of NR263S must be within the thermal derating curve ( Ambient Temperature vs. Power Dissipation characteristic ) shown in the data sheet.