E-L6920D Datasheet, PDF (9/13 Pages) STMicroelectronics – 1V HIGH EFFICIENCY SYNCRONOUS STEP UP CONVERTER

L6920
Table 7. Capacitors distributors main list
Manufacturer
Series
Cap Value (µF)
AVX
TPS
15 to 470
KEMET
T510/T494/
T495
10 to 470
PANASONIC
EEFCD
22 to 47
SANYO POSCAP
TPA/B/C
22 to 230
SPRAGUE
595D
100 to 390
Rated Voltage (V)
6.3
6
ESR (mΩ)
50 to 1500
30 to 1000
6.3
50 to 700
6.3
40 to 80
6.3
160 to 700
5.3 Inductor selection
Usually, inductors ranging between 5µH to 40µH satisfy most of the applications.
Small value inductors have smaller physical size and guarantee a faster response to load transient but in steady
state condition a bigger ripple on output voltage is generated. In fact the output ripple voltage is given by Ipeak
multiplied by ESR. Furthermore, as shown in equation (1), inductor size affects also the maximum current de-
liverable to the load. Lastly, a low series resistance is suggested if very high efficiency values are needed. Any-
way, the saturation current of the choke should be higher than the peak current limit of the device (1A).
Good surface mounting inductors are available from COILCRAFTS, COILTRONICS, MURATA and other souc-
es. In the following table are listed some suggested components.
Table 8. Inductors distributors main list
Manufacturer
Series
Inductor Value (uH)
Coilcraft
DO1813HC
22 to 33
DO1608
4.7 to 15
Coiltronics
UP1B
22 to 33
TP3
4.7 to 15
BI
HM76-2
22 to 33
HM76-1
4.7 to 10
Murata
LQN6C
10 to 22
Panasonic
ELL6SH
10 to 22
ELL6RH
5.1 to10
Sumida
CR43
4.7 to 10
Saturation Current (A)
1 to 1.2
0.9 to 1.5
1 to 1.2
0.97 to 1.6
1 to 1.2
1 to 1.5
1.2 to 1.7
0.9 to 1.5
11 to 1.55
0.84 to 1.15
5.4 Layout Guidelines
The board layout is very important in order to minimize noise, high frequency resonance problems and electro-
magnetic interference.
It is essential to keep as small as possible the high switching current circulating paths to reduce radiation and
resonance problems. So, the output and input cap should be very close to the device.
The external resistor dividers, if used, should be as close as possible to the pins of the device (FB and LBI) and
as far as possible from the high current circulating paths, to avoid pick up noise.
Large traces for high current paths and an extended groundplane, help to reduce the noise and increase the
efficiency.
For an example of recommended layout see the following evaluation board.
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