www.ti.com

DCGain=1

1/2

OPA2727

C

1

1nF

C

2

330pF

R

2

15.9kW

R

1

1.93kW

2.2nF

C

3

C

4

100pF

R

4

22.3kW

R

3

2.07kW

CutoffFrequency=50kHz

1/2

OPA2727

V

O

DFN PACKAGE

LAYOUT GUIDELINES

OPA727,, OPA2727

OPA4727, OPA728

SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007

Note:

FilterPro is a low-pass filter design program available for download at no cost from TI’s web site (www.ti.com). The

program can be used to determine component values for other cutoff frequencies or filter types.

Figure 34. Four-Pole Butterworth Sallen-Key Low-Pass Filter

The OPA727 series uses the DFN-8 (also known as

The leadframe die pad should be soldered to a

SON), which is a QFN package with lead contacts on

thermal pad on the PCB. A mechanical data sheet

only two sides of the bottom of the package. This

showing an example layout is attached at the end of

leadless, near-chip-scale package maximizes board

this data sheet. Refinements to this layout may be

space

and

enhances

thermal

and

electrical

required based on assembly process requirements.

characteristics through an exposed pad.

Mechanical drawings located at the end of this data

sheet list the physical dimensions for the package

DFN packages are physically small, have a smaller

and pad. The five holes in the landing pattern are

routing area, improved thermal performance, and

optional, and are intended for use with thermal vias

improved electrical parasitics, with a pinout scheme

that connect the leadframe die pad to the heatsink

that

is

consistent

with

other

commonly-used

area on the PCB.

packages, such as SO and MSOP. Additionally, the

absence of external leads eliminates bent-lead

Soldering the exposed pad significantly improves

issues.

board-level reliability during temperature cycling, key

push, package shear, and similar board-level tests.

The DFN package can be easily mounted using

Even

with

applications

that

have

low-power

standard

printed

circuit

board

(PCB)

assembly

dissipation, the exposed pad must be soldered to the

techniques. See Application Note, QFN/SON PCB

PCB to provide structural integrity and long-term

Attachment

(SLUA271)

and

Application

Report,

reliability.

Quad Flatpack No-Lead Logic Packages (SCBA017),

both available for download at www.ti.com.

The exposed leadframe die pad on the bottom of

the package should be connected to V–.

14

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