LTC4267-3
28
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applicaTions inForMaTion
low impedance alternate connection should be employed
between the PGND pins of the LTC4267-3 and the PGND
side of R
SENSE
, away from the high current loop. This
Kelvin sensing will ensure an accurate representation of
the sense voltage is measured by the LTC4267-3.
The placement of the feedback resistors R1 and R2 as
well as the compensation capacitor C
C
is very important
in the accuracy of the output voltage, the stability of the
main control loop, and the load transient response. In
an isolated design application, R1, R2, and C
C
should be
placed as close as possible to the error amplifier’s input
with minimum trace lengths and minimum capacitance. In
a nonisolated application, R1, and R2 should be placed as
close as possible to the V
FB
pin of the LTC4267-3 and C
C
should be placed close to the I
TH
/RUN pin of the LTC4267-3.
In essence, a tight overall layout of the high current loop
and careful attention to current density will ensure suc
-
cessful operation of the LTC4267-3 in a PD.
Place C14 (Figure 9) as close as physically possible to the
LTC4267-3. Place the series 10Ω resistor close to C14.
Excessive parasitic capacitance on the R
CLASS
pin should
be avoided. The SIGDISA pin is adjacent to the V
PORTP
pin and any coupling, whether resistive or capacitive may
inadvertently disable the signature resistance. To ensure
consistent behavior, the SIGDISA pin should be electri
-
cally connected and not left floating. Voltages in a PD can
be as large as –
57V, so high voltage layout techniques
should be employed.
