Cirrus Logic AN351 - Manual

Copyright  Cirrus Logic, Inc. 2011
(All Rights Reserved)
http://www.cirrus.com
Application Note
BOOST INDUCTANCE VS. INDUCTOR SIZE
1. INTRODUCTION
This application note explains the effects to performance of reducing the size of the boost inductor used
in the CDB150x-00 PFC demonstration board. The CDB150x-00 was designed using a 380 uH boost in-
ductor. However, for applications requiring a constant power load where the load is applied before V
link
has reached its nominal value, the system may fail to start. For these particular applications, reducing the
size of the boost inductor resolves this problem, but with slightly higher THD and lower efficiency. Please
see the Performance Plots section for specific information.
Presented in the following sections are the updated schematic and bill of materials. A complete set of per-
formance plots and oscilloscope waveforms are also included to demonstrate the system’s behavior with
the smaller boost inductor. Please reference the CDB150x-00 data sheet for comparison.
Extreme caution needs to be exercised while handling this board. This board is to be used by trained pro-
fessionals only. Prior to applying AC power to the CDB150x-00 board, the CS1500 needs to be biased
using an external 13 VDC power supply.
Figure 1. CS150x-00 Assembly
Boost Inductor (L5)
AN351
MAY ’11
AN351REV2