L6730C datasheet(14/50 Pages) STMICROELECTRONICS

Part #	L6730C

Description	Adjustable step-down controller with synchronous rectification

PDF	50 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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14 / 50 page

Device description

L6730C - L6730D

14/50

5.2

Internal LDO

An internal LDO supplies the internal circuitry of the device. The input of this stage is the VCC

pin and the output (5V) is the VCCDR pin (see Figure 4.).

5.3

Bypassing the LDO to avoid the voltage drop with low Vcc

The LDO can be by-passed, providing directly a 5V voltage to VCCDR. In this case Vcc and

VCCDR pins must be shorted together as shown in Figure 5. VCCDR pin must be filtered with at

least 1

µF capacitor to sustain the internal LDO during the recharge of the bootstrap capacitor.

VCCDR also represents a voltage reference for Tmask pin, S/O/U pin (L6730C) or CC/O/U pin

(L6730D) and PGOOD pin (see Table 3: Pins connection).

If Vcc

≈ 5V the internal LDO works in dropout with an output resistance of about 1Ω.

The maximum LDO output current is about 100mA and so the output voltage drop can be

100mV: to avoid this the LDO can be bypassed.

Figure 4.

LDO block diagram.

Figure 5.

Bypassing the LDO

LDO

4.5V

÷ 14V

L6730C Datasheet(PDF) 14 Page - STMicroelectronics