Datasheet

V
IN
= 60V
V
IN
= 48V
V
IN
= 40V
0 5 10 15 20
OUTPUT CURRENT (A)
V
OUT
(V)
6.0
8.0
10.0
12.0
14.0
40V < V
IN
< 60V
0 5 10 15 20
OUTPUT CURRENT (A)
EFFICIENCY (%)
80
85
90
95
100
LM5033
www.ti.com SNVS181B –APRIL 2004–REVISED APRIL 2013
APPLICATION CIRCUIT EXAMPLE
Figure 17 shows an example circuit for a half-bridge 200W DC/DC converter built in a quarter brick format. The
circuit is that of an intermediate bus converter (IBC) which operates open-loop (unregulated output), converting a
nominal 48V input to a nominal 9.0V output with a 30 mΩ output impedance. The current sense transformer (T2),
and the associated filter at the CS pin, provide overcurrent detection at approximately 23A. The auxiliary winding
on T1 powers V
CC
and the LM5100’s V+ pin (once the outputs are enabled) to reduce power dissipation within
the LM5033. The LM5100 provides appropriate level shifting for Q1. Synchronous rectifiers Q3 and Q4 minimize
conduction losses in the output stage. Dual comparators U2 and U3 provide under-voltage and over-voltage
sensing at Vin. The under-voltage sense levels are 37V increasing, and 33V decreasing. The over-voltage sense
levels are 63V increasing, and 61.5V decreasing. The circuit can be shut down by taking the ON/OFF input
below 0.8V. An external synchronizing frequency can be applied to the SYNC input. Measured efficiency and
output characteristics for this circuit are shown in Figure 15 and Figure 16.
Figure 15. Efficiency vs Output Current
Circuit of Figure 17
Figure 16. V
OUT
vs Load Current and V
IN
for the circuit of Figure 17
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