Table 9-2. Low-ESR Capacitor Manufacturers (continued)

MANUFACTURER

PHONE

WEBSITE

CAPACITOR TYPE

Tokin

(408)-432-8020

www.tokin.com

Ceramic chip capacitors

9.2.2.3 Paralleling Devices

Any number of LM2767 devices can be paralleled to reduce the output resistance. Because there is no closed

loop feedback, as found in regulated circuits, stable operation is assured. Each device must have its own

pumping capacitor C1, while only one output capacitor COUT is needed as shown in Figure 9-3. The composite

output resistance is:

R

OUT =

R

OUT

of each LM 2767

Number of Devices

(4)

Figure 9-3. Lowering Output Resistance by Paralleling Devices

9.2.2.4 Cascading Devices

Cascading the several LM2767 devices is an easy way to produce a greater voltage (a two-stage cascade circuit

is shown in Figure 9-4).

The effective output resistance is equal to the weighted sum of each individual device:

ROUT = 1.5 ROUT_1 + ROUT_2

(5)

Note that increasing the number of cascading stages is practically limited because it significantly reduces the

efficiency, increases the output resistance and output voltage ripple.

Figure 9-4. Increasing Output Voltage By Cascading Devices

9.2.2.5 Regulating VOUT

It is possible to regulate the output of the LM2767 by use of a low dropout regulator (such as LP2980-5.0). The

whole converter is depicted in Figure 9-5.

A different output voltage is possible by use of LP2980-3.3, LP2980-3.0, or LP2980-ADJ.

The following conditions must be satisfied simultaneously for worst case design:

LM2767

SNVS069E – FEBRUARY 2000 – REVISED JANUARY 2022

www.ti.com

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