L7983 datasheet(15/43 Pages) STMICROELECTRONICS

Part #	L7983

Description	60 V, 300 mA synchronous step-down switching regulator with 10 μA quiescent current

PDF	43 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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5.3

Switching frequency programming and dithering

The L7983 has one programming pin, FSW (pin 4), which is used to set the regulator free running switching

frequency.

The switching frequency programming feature is performed by selecting the proper 1% accuracy resistor, to be

mounted between pin 4 and ground or VCC, as summarized in the following table. The pinstrapping is active only

before the soft-start phase to minimize the IC consumption.

Refer also to Figure 1 for reference schematic.

Table 7. FSW pin programming resistor

Dithering enabled

Dithering disabled

RVCC [kΩ]

RGND [kΩ]

Fsw [kHz] (1)

RVCC [kΩ]

RGND [kΩ]

Fsw [kHz] (1)

1000

1,8

200

1,8

200

3,3

400

3,3

400

5,6

500

5,6

500

700

1500

2000

2200

1. Typical value. Refer to Table 6 for details.

L7983

Switching frequency programming and dithering

DS13354 - Rev 1

page 15/43

L7983 Datasheet(PDF) 15 Page - STMicroelectronics