LM2619

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SNVS212B – NOVEMBER 2002 – REVISED MAY 2013

Table 2. Suggested Inductors and Their Suppliers

Part Number

Vendor

Phone

FAX

DO1608C-103

Coilcraft

847-639-6400

847-639-1469

ELL6SH100M

Panasonic

714-373-7366

714-373-7323

ELL6RH100M

Panasonic

714-373-7366

714-373-7323

CDRH5D18-100

Sumida

847-956-0666

847-956-0702

P0770.103T

Pulse

858-674-8100

858-674-8262

For low-cost applications, an unshielded inductor is suggested. For noise critical applications, a toroidal or

shielded inductor should be used. A good practice is to lay out the board with footprints accommodating both

types for design flexibility. This allows substitution of a low-noise shielded inductor, in the event that noise from

low-cost unshielded models is unacceptable.

The saturation current rating is the current level beyond which an inductor loses its inductance. Different

manufacturers specify the saturation current rating differently. Some specify saturation current point to be when

inductor value falls 30% from its original value, others specify 10%. It is always better to look at the inductance

versus current curve and make sure the inductor value doesn’t fall below 30% at the peak current rating of the

LM2619. Beyond this rating, the inductor loses its ability to limit current through the PWM switch to a ramp. This

can cause poor efficiency, regulation errors or stress to DC-DC converters like the LM2619. Saturation occurs

when the magnetic flux density from current through the windings of the inductor exceeds what the inductor’s

core material can support with a corresponding magnetic field.

CAPACITOR SELECTION

Use a 10µF ceramic input capacitor. Use X7R or X5R types, do not use Y5V.

Use of tantalum capacitors is not recommended.

Ceramic capacitors provide an optimal balance between small size, cost, reliability and performance for cell

phones and similar applications. A 22µF ceramic output capacitor is recommended for applications that require

increased tolerance to heavy load transients. A 10µF ceramic output capacitor can be used in applications where

the worst case load transient step is less than 200mA. Use of a 10µF output capacitor trades off smaller size for

an increase in output voltage ripple, and undershoot during load transients. Table 3 lists suggested capacitors

and suppliers.

The input filter capacitor supplies current to the PFET switch of the LM2619 in the first part of each cycle and

reduces voltage ripple imposed on the input power source. The output filter capacitor smooths out current flow

from the inductor to the load, helps maintain a steady output voltage during transient load changes and reduces

output voltage ripple. These capacitors must be selected with sufficient capacitance and sufficiently low ESR to

perform these functions.

The ESR, or equivalent series resistance, of the filter capacitors is a major factor in voltage ripple.

Table 3. Suggested Capacitors and Their Suppliers

Model

Type

Vendor

Phone

FAX

C1, C2 (Input or Output Filter Capacitor)

C2012X5ROJ106M

Ceramic

TDK

847-803-6100

847-803-6296

JMK212BJ106MG

Ceramic

Taiyo-Yuden

847-925-0888

847-925-0899

ECJ3YB0J106K

Ceramic

Panasonic

714-373-7366

714-373-7323

JMK325BJ226MM

Ceramic

Taiyo-Yuden

847-925-0888

847-925-0899

C3225X5RIA226M

Ceramic

TDK

847-803-6100

847-803-6296

DSBGA PACKAGE ASSEMBLY AND USE

Use of the DSBGA package requires specialized board layout, precision mounting and careful reflow techniques,

as detailed in application note AN-1112. Refer to the section Surface Mount Technology (SMT) Assembly

Considerations. For best results in assembly, alignment ordinals on the PC board should be used to facilitate

placement of the device.

Copyright © 2002–2013, Texas Instruments Incorporated

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