Rev. 4.0 5/22/2010
International Rectifier
Page 14 of 16
PROPRIETARY INFORMATION - This document and the information contained therein are proprietary and are not to be reproduced, used or disclosed
to others for manufacture or any other purpose except as specifically authorized in writing by
INTERNATIONAL RECTIFIER.
5.4 User Initiated SLEEP Mode
The CT/SD pin of IRS27951 can be used to disable the IC and enter sleep mode in which the IC power
consumption is highly minimized. The IC enters this mode when the CT/SD pin is externally pulled to COM.
This feature facilitates the implementation of system power management functions for reducing overall standby
power consumption by disabling the down converter when no power is being requested by the converter main
output voltage rails.
Ch 1: Low-side device V
GS
Ch 2
: CT/SD pin of IRS27951
Ch 3
: High-side device V
GS
Ch 4
: Resonant tank current
Sleep mode initiated by externally pulling the CT/SD pin to COM
5.5 Efficiency Chart
The efficiency of IRS27951 demo board was tested at both 270Vac input and 400Vdc input over the load
range. The result is shown in the table below.
270Vac
400Vdc
24Vout
24V
current(A)
12Vout
12V current
(A)
Pout(W) Efficiency Efficiency
24.176
1.5
11.97
1.5
54.2
90.8%
91.0%
24.2
3
11.92
3
108.4
92.6%
92.6%
24.22
4.5
11.9
4.5
162.5
92.4%
92.9%
24.24
6
11.86
6
216.6
92.2%
92.7%
23.517
6
12.26
0
141.1
92.8%
24.814
0
11.63
6
69.8
89.5%