S-BEC
The World's Smallest, Lightest Switch-Mode Super BEC
S-BEC is a highly integrated and sophisticated switch-mode power supply operating
from 5.5V to 50V input and producing a constant 5V output, with any load up to 2.5A
continuous – suitable for up to 8 standard servos or 6 digital servos. Besides being the
smallest and lightest switch-mode BEC in the world, thanks to the latest integrated
circuit technology, it also has the highest input voltage rating, allowing the use of up to
41 NiCd or Ni-MH cells (1.2V per cell). S-BEC is also compatible with Li-Ion and Li-Poly
cells. S-BEC has special components to cater for the high instantaneous current draw
that servos usually require. Although this instantaneous current may be above 2.5A,
the continuous current draw of each servo is very much less, and S-BEC is designed to
handle both these current ‘spikes’ and the continuous current requirements of both
standard and digital servos.
* 5.5 V to 50 V input1
* 2.5 Amp continuous output current.
·* Low ripple voltage.
* Exceptionally low EMI (electronically
quiet).
* Short circuit protection.
6 cells minimum, up to 33 cells at
1.5V/cell or 41 cells at 1.2V/cell
1
Min
Typical Max
Units
Input voltage
5.5
-
50
V
Output voltage
4.9
5.0
5.1
V
Current consumption
5.1
5.5
5.9
mA
Output current (continuous)
-
-
2.5
A
-
-
19 x 15 x 8
mm
-
-
.75 x .59 x
.32
inch
7.5
9
10 with
switch
g
Size (L x W x H)
Weight
Until the introduction of the S-BEC, switching BEC were noted for producing high noise
levels, which can interfere with radio reception. But the new S-BEC is much smaller
and the tracks, which become antennas that radiate EMI, are as short as 5mm. This
greatly reduces emissions and also takes them into a non-conflicting frequency range.
S-BEC also uses a shielded inductor, which was the biggest source of EMI in nonshielded switching BEC. Another unique feature of the S-BEC is that the switching
circuitry, including MOSFETs, are all packed in a single monolithic device, which
further quiets the device.
In fact, Electronic Speed Controllers (ESC) for throttle control generate noise several
times that of the S-BEC. Just the same, both ESC and S-BEC should be placed as far
as possible from the receiver. That is simply safest, standard practice.
Connections
Connect the red and black input leads to the battery, making sure that the polarity is
correct. Red is connected to the Positive (+) battery terminal while black is connected
to the Negative (-) battery terminal. Connect the 3‑ way RC connector to the receiver
battery socket or an unused socket. Note that although the orange (signal) lead is
present on the 3-way RC cable, it is unused and is only to help with correct polarity
alignment. The figure below shows a typical electric model setup with S‑ BEC used to
supply power to the receiver from a high-cell-count battery pack. If your ESC uses
integrated BEC circuit, be sure to disable it following the manufacturer’s instructions.
Usually this can be accomplished by removing the pin for (+) voltage from the ESC’s
connector to receiver throttle channel.
Operation
As soon as power is applied to S-BEC, 5V will be present at the output. If the input
voltage drops below 5.5V, the output will fall below 5.0V and will maintain
approximately 0.5V below the input voltage. This means that S-BEC is only
recommended for 6 cells or more – up to 41 Nickel Cadmium (Ni-Cd) or Nickel-MetalHydride (Ni-MH) cells. Note that while charging, Ni-Cd and Ni-MH cells may attain up
to 1.7V per cell. If 30 cells or more are used with S-BEC, the battery voltage may rise
above the maximum 50V input limit so care should be taken to make sure that S-BEC
is disconnected while charging. S-BEC is also compatible with Li‑ Ion and Li-Poly cells,
as long as the voltage is below 50V.
The graph below shows the typical efficiency of S-BEC constructed from actual data.