lm5015mhx National Semiconductor Corporation, lm5015mhx Datasheet - Page 19

• Manufacturer Part Number: lm5015mhx
• Description: High Voltage Monolithic Two-switch Forward Dc-dc Regulator
• Manufacturer: National Semiconductor Corporation

IC. Judicious positioning of the PC board within the end prod-
uct, along with use of any available air flow will help reduce
the junction temperature. If using forced air cooling, avoid
placing the LM5015 in the airflow shadow of large compo-
nents, such as input or output capacitors, inductors or trans-
formers.
Application Examples
The following schematics present four examples dc-dc con-
verters utilizing the LM5015 switching regulator IC:
1.
2.
3.
Non-Isolated Two-Switch Forward for 48V input and 5V
2.5A output,
Isolated Two-Switch Forward for 48V input and 5V 2.5A
output
Isolated Two-Switch Flyback converter for 48V input and
5V 2.5A output,
FIGURE 12. Non-Isolated Two-Switch Forward
19
4.
48V NON-ISOLATED TWO-SWITCH FORWARD
The Non-Isolated Two-Switch Forward converter shown in
Figure 12 utilizes the internal voltage reference for the regu-
lation set-point. The output is +5V at 2.5A while the input
voltage can vary from 36V to 72V. The switching frequency is
300 kHz. An auxiliary winding on transformer (T1) provides
10V to power the LM5015 when the output is in regulation.
This disables the internal high voltage VCC LDO regulator
and improves efficiency. The converter can be shut down by
driving the EN input below 1.26V with an open-collector or
open-drain transistor. An external synchronizing frequency
can be applied to the SYNC input.
A 1:1 dc-dc transformer with the input/output operating
range of 5V to 15V
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