HA16163T Datasheet, PDF (16/30 Pages) Renesas Technology Corp – Synchronous Phase Shift Full-Bridge Control IC

HA16163T
• Subinterval:2
As SD is turned off at point t1, the primary-side current flows into resonant capacitance Cr2. At this time Cr2 is
charged, and therefore the potential of V12 rises. Considering that the exciting current and the L1 and L2 ripple
currents are considerable smaller than Io, the following is an approximate equation for the slope of V12.
dV12
dt
=
0.5 Io
N
⋅
1
Cr2
[V/s]
⋅⋅⋅⋅⋅(1)
Here, N is the ratio of the primary coil to the secondary coil (N = N1/N2), and Io is the output current.
As SE and SF are on, the transformer secondary side is in the shorted state, and the value of the current flowing up
to that time is retained.
VIN
L1
SA
V11
Lr
Cr1 ^SB
SC
SE
V12
VOUT
SD _Cr2
SF
L2
Subinterval: 2
• Subinterval:3
SC is turned on at point t2. ZVS operation can be attained by setting the SD off (t2) → SC on (t3) delay to the
optimal value. This delay time can be expressed by equation (2).
TD2 = ^N ⋅ Cr2 ⋅ VIN [s]
0.5 Io
⋅⋅⋅⋅⋅(2)
After SC is turned on, the transformer primary side is in the shorted state, and therefore the current value
immediately after SC was turned on is retained.
VIN
L1
SA
V11
Lr
Cr1 ^SB
SC
SE
V12
VOUT
SD _Cr2
SF
L2
Subinterval: 3
Rev.5.0, Mar.15.2004, page 16 of 29