LM3263

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SNVS837 – JUNE 2013

APPLICATION INFORMATION

Recommended External Components

Inductor Selection

A 1.5 µH inductor is needed for optimum performance and functionality of the LM3263. In the case of 2G

transmission current bursts, the effective overall RMS current requirements are reduced. Therefore, please

consult with the inductor manufacturers to determine if some of their smaller components will meet your

application needs even though the classical inductor specification does not appear to meet the LM3263 RMS

current specifications.

The LM3263 automatically manages the inductor peak and RMS current (or steady-state current peak) through

the SW pin. The SW pin has two positive current limits. The first is the 1.45A typical (or 1.65A maximum) over-

current protection. It sets the upper steady-state inductor peak current (as detailed in the Electrical

second is an over-limit current protection. It limits the maximum peak inductor current during large signal

transients (i.e., < 20 µs) to 1.9A typical (or 2.1A maximum). A minimum inductance of 0.3uH should be

maintained at the second current limit.

The ACB circuit automatically adjusts its output current to keep the steady-state inductor current below the

steady-state peak current limit. Thus, the inductor RMS current will effectively always be less than the

bursts, the effective overall RMS current would be much lower.

For good efficiency, the inductor’s resistance should be less than 0.2

Ω; low DCR inductors (<0.2Ω) are

recommended. Table 2 suggests some inductors and their suppliers.

Table 2. Suggested Inductors and Their Suppliers

Model

Vendor

Dimensions (mm)

(30% drop in

DCR

inductance)

DFE201610C1R5N

TOKO

2.2A

120 m

Ω

(1285AS-H-1R5M)

LQM2MPN1R5MG

Murata

2.0A

110 m

Ω

2.0 x 1.6 x 1.0

MAKK2016T1R5M

Taiyo-Yuden

1.9A

115 m

Ω

VLS201610MT-1R5N

TDK

1.4A

151 m

Ω

Capacitor Selection

The LM3263 is designed to use ceramic capacitors for its input and output filters. Use a 10 µF capacitor for the

input and approximately 10 µF actual total output capacitance. Capacitor types such as X5R, X7R are

recommended for both filters. These provide an optimal balance between small size, cost, reliability and

performance for cell phones and similar applications. Table 3 lists suggested part numbers and suppliers. DC

bias characteristics of the capacitors must be considered while selecting the voltage rating and case size of the

capacitor. Smaller case sizes for the output capacitor mitigate piezo-electric vibrations of the capacitor when the

output voltage is stepped up and down at fast rates. However, they have a bigger percentage drop in value with

dc bias. For even smaller total solution size, 0402 (1005) case size capacitors are recommended for filtering. Use

of multiple 2.2 µF or 1µF capacitors can also be considered. For RF Power Amplifier applications, split the output

total capacitance (taking into account effects of capacitor DC bias, temperature de-rating, aging and other

capacitors very close to the respective device. A high-frequency capacitor (3300 pF) is highly recommended to

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