E-L6920D Datasheet, PDF (8/13 Pages) STMicroelectronics – 1V HIGH EFFICIENCY SYNCRONOUS STEP UP CONVERTER

L6920
Figure 12. Demoboard Circuit
+VBATT
R1
N.C. _LBI
R2
N.C.
VBATT
7
2
8
VREF
C4
100nF
L6920
4
3
GND
6
5
1
F.B.
not mounted components
Panasonic
ELL6RH100M
L1 10µH
VOUT
C3
R3
N.C.
N.C.
LBO
C2
47µF
C1
47µF
+VBATT
Panasonic
EEFCDJ470R
GND
VOUT
Panasonic
EEFCDJ470R
GND
LBO
SHDN
1
2
J1 3
1 ^{R4 N.C.}
2
J2
3 _{R5 N.C.}
D01IN1310
SHDN
Table 6.
Jumper
J1
J2
Position
1-2
2-3
None
1-2
2-3
Function
Device enabled
Device disabled
Adjustable using R4 and R5 [not mounted]
3.3V output voltage
5V output voltage
R4, R5 should be selected in the range of 100kΩ - 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 10µF-100µF.
An additional, smaller, low ESR capacitor can be in parallel for high frequency filtering. A typical value can be
around 1µF.
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
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