0

5

10

15

20

OUTPUT CURRENT (A)

6.0

8.0

10.0

12.0

14.0

0

5

10

15

20

OUTPUT CURRENT (A)

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 m

Ω output impedance. The current sense transformer (T2),

and the associated filter at the CS pin, provide overcurrent detection at approximately 23A. The auxiliary winding

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

for the circuit of Figure 17

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