ha16163t Renesas Electronics Corporation., ha16163t Datasheet - Page 17

• Manufacturer Part Number: ha16163t
• Description: Synchronous Phase Shift Full-bridge Control Ic
• Manufacturer: Renesas Electronics Corporation.

HA16163T
• Subinterval:4
• Subinterval:5
Rev.5.0, Mar.15.2004, page 17 of 29
As SA is turned off at point t3, the primary-side current discharges resonant capacitance Cr1, and the potential of
V11 falls. A negative potential is applied to resonant inductor Lr, and a flux reset starts. At this time, since the
series resonance circuit is composed of Cr1 and Lr, the V11 waveform changes to a sine wave. The resonance
frequency is given by equation (3).
When synchronous switch SF is turned off at point t4, the current flowing in SF up to that time continues to flow
through the SF body diode. SF turn-off must be performed before completion of the resonant inductor Lr flux reset.
If SF is not off on completion of the Lr flux reset, power transmission will be performed with the transformer
secondary-side shorted, and therefore an excessive current will flow in the transformer primary and secondary sides,
and parts may be damaged.
Also, if the SF body diode is on for a long period, loss will be high. Therefore, optimal timing should be set by
means of the HA16163's delay adjustment pin, DELAY-3.
Lr reset time tr is given by equation (4) when the resonance voltage peak value is within the input voltage.
Here, vpp is the resonance voltage peak value.
fr =
treset(Lr)|
vpp =
2
Io
2
(Cr1 Lr)
vpp VIN
1
N
1
Cr1
Cr1
(Lr/Cr1)
=
= 0.5
1
4
[Hz]
V11
V11
SA
SB
SA
SB
fr
1
(Cr1 Lr)
[V]
VIN
VIN
Lr
Lr
[s]
(3)
(4)
(5)
Subinterval: 4
Subinterval: 5
SC
V12
SD
SC
V12
SD
Cr2
Cr2
SF
SE
SF
SE
L1
L2
L1
L2
VOUT
VOUT