HA16163T Datasheet, PDF (17/30 Pages) Renesas Technology Corp – Synchronous Phase Shift Full-Bridge Control IC

HA16163T
• Subinterval:4
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).
fr =
1
[Hz]
2π √(Cr1 ⋅ Lr)
⋅⋅⋅⋅⋅(3)
VIN
L1
SA
V11
Lr
Cr1 ^SB
SC
SE
V12
VOUT
SD _Cr2
SF
L2
Subinterval: 4
• Subinterval:5
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.
treset(Lr)|_vpp≤VIN =
1_â‹
4
1
fr
= 0.5π √(Cr1 ⋅ Lr) [s] ⋅⋅⋅⋅⋅(4)
Here, vpp is the resonance voltage peak value.
vpp = ^Io ⋅ ¹ ⋅ √(Lr/Cr1) [V]
2N
⋅⋅⋅⋅⋅(5)
VIN
L1
SA
V11
Lr
Cr1 ^SB
SC
V12
SD _Cr2
SE
SF
VOUT
L2
Subinterval: 5
Rev.5.0, Mar.15.2004, page 17 of 29