L6920

8/13

Figure 12. Demoboard Circuit

Table 6.

R4, R5 should be selected in the range of 100k

Ω - 10MΩ to minimize consumption and error due to current sunk

by FB pin (few nA).

5.2 Output capacitor selection

The output capacitor affects both efficiency and output ripple so its choice has to be considered with particular

care.

The capacitance value should be in the range of about 10

µF-100µF.

An additional, smaller, low ESR capacitor can be in parallel for high frequency filtering. A typical value can be

around 1

µF.

If very high performances, in terms of efficiency and output voltage ripple, are required, a very low ESR capac-

itor has to be chosen.

Ceramic capacitors are the lowest ESR but they are very expensive.

Other possibilities are low-ESR tantalum capacitors, available from KEMET, AVX and other sources. POSCAP

capacitors from SANYO and polymeric capacitors from PANASONIC are also good.

Below there is a list of some capacitors suppliers. The cap values and rated voltages are only a suggested pos-

sibility

Jumper

Position

Function

J1

1-2

Device enabled

2-3

Device disabled

J2

None

Adjustable using R4 and R5 [not mounted]

1-2

3.3V output voltage

2-3

5V output voltage

L1 10

µH

+VBATT

+VBATT

VBATT

F.B.

VOUT

7

1

8

GND

Panasonic

ELL6RH100M

Panasonic

EEFCDJ470R

Panasonic

EEFCDJ470R

C2

47

µF

C3

N.C.

C1

47

µF

C4

100nF

R1

N.C.

R3

N.C.

R2

N.C.

not mounted components

R4 N.C.

R5 N.C.

VOUT

GND

1

2

3

3

2

J2

J1

1

LBO

3

SHDN

5

VREF

GND

4

6

LBI

2

LBO

SHDN

L6920

D01IN1310