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BCD.00197 Rev AG, 09-Mar-2021

Page 4 of 11

IBX15 Series

Boost Converters

© 2021 Bel Power Solutions & Protection

Efficiency

60

70

80

90

0.4

0.8

0

JM121

Vi = 24 V

100

η [%]

0.6

0.2

Vi = 36 V

Fig. 3

Efficiency versus input voltage and output current (24IBX15-50-0G)

Interruption Time

The interruption time of a system comprised of a step-up converter IBX15 (Rev. AB or later) and connected converters can easily

be increased by an external capacitor C

As an example, fig. 4 shows a 36IBX15-50 supplying a DC-DC converter 110IMY70-12.

Formula for the external boost capacitor C

2 • P

C

(V

oB tr

2

– V

i min

2

)

whereas:

C

hu

= external boost capacitance [mF]

P

o

= output power = input power of the supplied converter [W]

t

hu

= interruption or hold-up time [ms]

V

i min

= min. input voltage of supplied converters [V]

V

oB tr

= boost voltage trimmed using R

JM123

+

Output

+

+

+

36IBX15

110IMY70-12

Input

80

60

40

0

0

10

20

20

30

[V]

t

JM122

ms

120

100

Fig. 4

System with increased interruption time

Fig. 5

Increased interruption time. V

P

The external boost capacitor is loaded by a current source to the preselected boost voltage V

after V

Consequently, its rated voltage needs not to be much higher than V

In the case of input voltage loss, the output voltage V

capacitor, sustaining the output voltage; see fig. 5. As long as V

voltage of the supplied converter is not affected.