AN2115 datasheet(10/33 Pages) STMICROELECTRONICS

Part #	AN2115

Description	This application note details the main features

PDF	33 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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10 / 33 page

Operation description

AN2115

10/33

Doc ID 11165 Rev 5

Basically, the device switches with its internal free running frequency of 1.4 MHz. Obviously,

in very light load conditions, the device could skip some cycles in order to keep the output

voltage regulated. In Figure 6 and Figure 7 the LCM and LNM typical waveforms are shown.

Figure 6.

Low consumption mode

Figure 7.

Low noise mode

●

Measurement conditions:

–Vin = 4.2 V

–Vout = 1.5 V

–Iout = 30 mA

–

L = 3.3 µH

–CIN = 10 µF

–COUT = 10 µF

–RC = 20 kΩ

–CC = 330 pF

A comparison between the efficiency in low noise mode and low consumption mode is

shown in Figure 19 of this document.

Red line: inductor current

Blue line: output voltage (AC coupled)

Green line: LX pin

Red line: inductor current

Blue line: output voltage (AC coupled)

Green line: LX pin

AN2115 Datasheet(PDF) 10 Page - STMicroelectronics