IR1167ABPBF データシートの表示（PDF） - International Rectifier
部品番号
コンポーネント説明
メーカー
IR1167ABPBF Datasheet PDF : 16 Pages
| |||
IR1167AS/BS
cycle of the SR MOSFET and, as a consequence, the
max duty cycle of the primary side switch.
DCM/CrCM Turn-off phase
Once the SR MOSFET has been turned on, it will
remain on until the rectified current will decay to the
level where VDS will cross the turn-off threshold VTH1.
This will happen differently depending on the mode
of operation.
In DCM the current will cross the threshold with a
relatively low dI/dt. Once the threshold is crossed, the
current will start flowing again through the body diode,
IPRIM
is blanked for a certain amount of time (TBLANK) after
VTH1 has been triggered.
The blanking time is internally set. As soon as VDS
crosses the positive threshold VTH3 also the blanking
time is terminated and the IC is ready for next
conduction cycle.
CCM Turn-off phase
In CCM mode the turn off transition is much steeper
and dI/dt involved is much higher. The turn on phase
is identical to DCM or CrCM and therefore won’t be
repeated here.
During the SR FET conduction phase the current will
decay linearly, and so will VDS on the SR FET.
VPRIM
IPRIM
T1
ISEC
VSEC
T2
T3
time
time
Primary and secondary currents and
voltages for DCM mode
IPRIM
VPRIM
T1
T2
ISEC
VSEC
time
time
Primary and secondary currents and
voltages for CrCM mode
causing the VDS voltage to jump negative. Depending
on the amount of residual current, VDS may trigger
once again the turn on threshold: for this reason VTH2
VPRIM
T1
T2
ISEC
VSEC
time
Primary and secondary currents and time
voltages for CCM mode
Once the primary switch will start to turn back on, the
SR FET current will rapidly decrease crossing VTH1
and turning the gate off.
The turn off speed is critical to avoid cross conduction
on the primary side and reduce switching losses.
also in this case a blanking period will be applied, but
given the very fast nature of this transition, it will be
reset as soon as VDS crosses VTH3.
www.irf.com
8
Share Link: 