P9028AC datasheet(21/39 Pages) RENESAS

21 / 39 page

P9028AC

Product Datasheet

Revision 1.0.3

APPLICATIONS INFORMATION

EXTERNAL COMPONENTS

The P9028AC requires a minimum number of external

components for proper operation, as indicated in Figure

16, 17 and 18 as well as Table 9, 10 and 11.

LDO

Input Capacitor (VRECT Capacitors)

The LDO input capacitors (VRECT capacitors) should be

located as close as possible to the VRECT pins, and

ground (PGND). Ceramic capacitors are recommended for

their lower ESR and small profile. See Figure 17 and

Table 10 for values and type of capacitor.

VDD Capacitor

The P9028AC has an internal LDO regulator that must

have a capacitor connected from the VDD pin to GND.

This capacitor should be as close as possible to the VDD

pin with a close GND connection. See Figure 17, 18 and

Table 10, 11 for values and type of capacitor.

Output Capacitor

The output capacitor connection to the ground pin (PGND)

should be made as short as practical for maximum device

performance. Since the LDO has been designed to

function with very low ESR capacitors, a ceramic capacitor

is recommended for best performance. For better transient

response increase the total amount of output capacitance.

For 1A load steps, an output capacitance of at least 10µF

is recommended.

PCB LAYOUT CONSIDERATIONS

For optimum device performance and lowest output

phase noise, the following guidelines should be

observed. Please contact IDT Inc. for Gerber files that

contain the recommended board layout and

application

note

AN883,

“P9028AC

Layout

Guidelines”.

An optimum layout is one with all components on the

same side of the board, minimizing vias through other

signal layers.

Signal traces not related to the

P9028AC should be routed away from the IC as much

as possible to avoid blocking thermal dissipation

paths from the IC to the PCB. This includes signal

traces just underneath the device, or on layers

adjacent to the ground plane layer used by the device.

Layout and PCB design have a significant influence

on the power dissipation capabilities of power

management ICs because the surface mount

packages used with these devices rely heavily on

thermally conductive traces or pads to transfer heat

away from the package. Appropriate PC layout

techniques should be used to remove the heat due to

device power dissipation.

The following general guidelines will be helpful in

designing a board layout for lowest thermal

resistance:

1. PC board traces with large cross-sectional

areas remove more heat. For optimum

results, use large-area PCB patterns with

wide copper traces, placed on the

uppermost side of the PCB.

2. In cases where maximum heat dissipation is

required, use double-sided copper planes

connected with multiple vias.

3. Thermal vias are needed to provide a

thermal path to inner and/or bottom layers of

the PCB to remove the heat generated by

device power dissipation.

POWER DISSIPATION

AND THERMAL REQUIREMENTS

The P9028AC is offered in a QFN-32 package which has

a maximum power dissipation capability of about 1.9W

and in a WLCSP package, the maximum power

dissipation of which is determined by the number of

thermal vias between the package and the printed circuit

board. The maximum power dissipation of both packages

is defined by the die’s specified maximum operating

junction temperature, TJ, of 125°C. The junction

temperature rises when the heat generated by the

device’s power dissipation goes through the package

thermal resistance. The QFN package offers a typical

thermal resistance, junction to ambient (ΘJA), of 35OC/W

when the PCB layout and surrounding devices are

optimized as described in the PCB Layout Considerations

section. The WLCSP package has a typical ΘJA of 70ºC/W

with 7 thermal vias and 144ºC/W with no thermal vias.

Clearly, maximizing the thermal vias is highly

recommended. The techniques as noted in the PCB

layout section must be followed when designing the

printed circuit board layout, as well as the placement of

the P9028AC IC package in proximity to other heat-

P9028AC Datasheet(PDF) 21 Page - Renesas Technology Corp

P9028AC Datasheet(HTML) 21 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Datasheet Download

Link URL