RLIM1 value is chosen by Equation 15. RLIM2 value is chosen by
Equation 14.
where RLIM_MAX_L is the smallest value between RLIM_MAX_L1 and RLIM_MAX_L2 in the Single RLIM Resistor Selection Section, and 0.5V represents the diode forward voltage drop of DLIM.
When the calculated RLIM1 and RLIM2 values have large enough difference, the RDR improvement on efficiency will be significant. If RLIM1 and RLIM2 values are close, then single RLIM resistor can be considered to reduce the external components.
The power loss of RLIM1 can be derived as
Equation 15.
where
Equation 16.
The power loss of RLIM2 can be approximated as
Equation 17.
The maximum voltage rating of diode D
LIM
needs to consider the highest V
VDD-to-VEE. The maximum current rating of
D
LIM can be chosen based on the derating from the worst-case
continuous current, (V
COM-to-VEE – V
F_DLIM) /
R
LIM2, where V
F_DLIM is the forward voltage of
D
LIM. The diode package size is determined based on the power loss in
forward conduction, P
Loss_DLIM = V
F_DLIM x
((V
COM-to-VEE – V
F_DLIM) / R
LIM2). A Schottky
diode is recommended to reduce the power loss.