LTC4267CDHC datasheet(27/32 Pages) LINEAR

27 / 32 page

LTC4267

4267fc

with minimum trace lengths and minimum capacitance.

In a nonisolated application, R1, and R2 should be placed

as close as possible to the VFB pin of the LTC4267 and

CC should be placed close to the ITH/RUN pin of the

LTC4267.

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 in a PD.

The PD interface section of the LTC4267 is relatively im-

mune to layout problems. Excessive parasitic capacitance

on the RCLASS pin should be avoided. If using the DHC

package, include an electrically isolated heat sink to which

the exposed pad on the bottom of the package can be

soldered. For optimum thermal performance, make the

heat sink as large as possible. The SIGDISA pin is adjacent

to the VPORTP pin and any coupling, whether resistive

APPLICATIO S I FOR ATIO

or capacitive may inadvertently disable the signature

resistance. To ensure consistent behavior, the SIGDISA

pin should be electrically connected and not left ﬂoating.

Voltages in a PD can be as large as – 57V, so high voltage

layout techniques should be employed.

Electro Static Discharge and Surge Protection

The LTC4267 is speciﬁed to operate with an absolute

maximum voltage of –100V and is designed to tolerate

brief overvoltage events. However, the pins that interface

to the outside world (primarily VPORTN and VPORTP) can

routinely see peak voltages in excess of 10kV. To protect

the LTC4267, it is highly recommended that a transient

voltage suppressor be installed between the diode bridge

and the LTC4267 (D3 in Figure 2).

LTC4267CDHC Datasheet(PDF) 27 Page - Linear Integrated Systems