NJW4170 datasheet(21/24 Pages) NJRC

Part #	NJW4170

Description	Current Mode Control High Speed Frequency Internal 1A MOSFET Switching Regulator IC for Buck Converter

PDF	24 Pages

Scroll/Zoom	100%

Manufacturer	NJRC [New Japan Radio]

Direct Link	http://www.jrc.co.jp/eng/index.html

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21 / 24 page

NJW4170

- 21 -

Ver.2016-01-25

Calculation of Package Power

A lot of the power consumption of buck converter occurs from the internal switching element (Power MOSFET).

Power consumption of NJW4170 is roughly estimated as follows.

Input Power:

PIN = VIN IIN [W]

Output Power:

POUT = VOUT IOUT [W]

Diode Loss:

PDIODE = VF IL(avg) OFF duty [W]

NJW4170 Power Consumption: PLOSS = PIN POUT PDIODE [W]

Where:

VIN

: Input Voltage for Converter

IIN

: Input Current for Converter

VOUT

: Output Voltage of Converter

IOUT

: Output Current of Converter

: Diode's Forward Saturation Voltage

IL(avg)

: Inductor Average Current

OFF duty

: Switch OFF Duty

Efficiency ( ) is calculated as follows.

= (POUT PIN) 100 [%]

You should consider temperature derating to the calculated power consumption: PD.

You should design power consumption in rated range referring to the power dissipation vs. ambient temperature

characteristics.

Technical Information

NJW4170 Application Manual

NJW4170 Datasheet(PDF) 21 Page - New Japan Radio