LTM8008HVPBF LINER [Linear Technology], LTM8008HVPBF Datasheet - Page 11

• Manufacturer Part Number: LTM8008HVPBF
• Description: 72VIN, 6 Output DC/DC SEPIC ?Module Regulator
• Manufacturer: LINER [Linear Technology]

applicaTions inForMaTion
4. Connect all of the GND connections to as large a copper
5. For good heatsinking, use vias to connect the GND cop-
pour or plane area as possible on the top layer. Avoid
breaking the ground connection between the external
components and the LTM8008.
per area to the board’s internal ground planes. Liberally
distribute these GND vias to provide both a good ground
connection and thermal path to the internal planes of the
printed circuit board. Pay attention to the location and
density of the thermal vias in Figure 3. The LTM8008
can benefit from the heat-sinking afforded by vias that
connect to internal GND planes at these locations, due to
their proximity to internal power handling components.
The optimum number of thermal vias depends upon
the printed circuit board design. For example, a board
might use very small via holes. It should employ more
thermal vias than a board that uses larger holes.
CAPACITORS
Figure 3. Layout Showing Suggested External Components, GND Plane and Interconnect/Thermal Vias
OUTPUT
LDO
GND
SPV
SPV
C
INTVCC
LDO OUTPUT CAPACITOR
CONTROL DISCRETES
Post Regulator Output Capacitance and Transient
Response
The LTM8008 linear post regulators are designed to be
stable with a wide range of output capacitors. The ESR
of the output capacitor affects stability, most notably with
small capacitors. The output transient response will be a
function of output capacitance. Larger values of output
capacitance decrease the peak deviations and provide im-
proved transient response for larger load current changes.
Bypass capacitors, used to decouple individual components
powered by the post regulators, will increase the effective
output capacitor value. Extra consideration must be given
to the use of ceramic capacitors. Ceramic capacitors are
manufactured with a variety of dielectrics, each with dif-
ferent behavior across temperature and applied voltage.
The most common dielectrics used are specified with EIA
temperature characteristic codes of Z5U, Y5V, X5R and
SW
GND
V
IN
C
OUT
CAPACITOR
INDUCTOR
COUPLED
FLYING
L1
C
OUT
POWER
DIODE
SPV
LTM8008
C
V
IN
IN
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