LLCC68 datasheet(31/106 Pages) SEMTECH

31 / 106 page

LLCC68

Data Sheet

Rev. 1.0

DS.LLCC68.W.APP

July 2019

31 of 106

Semtech

www.semtech.com

5.1.3 Consideration on the DC-DC Inductor Selection

The selection of the inductor is essential to ensure optimal performance of the DC-DC internal block. Selecting an incorrect

inductor could cause various unwanted effects ranging from ripple currents to early aging of the device, as well as a

degradation of the efficiency of the DC-DC regulator.

For the LLCC68, the preferred inductor will be shielded, presenting a low internal series resistance and a resonance

frequency much higher than the DC-DC switching frequency. When selecting the 15 μH inductor, the user should therefore

select a part with the following considerations:

•

DCR (max) = 2 ohms

•

Idc (min) = 100 mA

•

Freq (min) = 20 MHz

5.2 Flexible DIO Supply

The transceiver has two power supply pins, one for the core of the transceiver called VBAT and one for the host controller

interface (SPI, DIOs, BUSY) called VBAT_IO. Both power supplies can be connected together in application. In case a low

voltage micro-controller (typically with IO pads at 1.8 V) is used to control the transceiver, the user can:

•

use VBAT at 3.3 V for optimal RF performance

•

directly connect VBAT_IO to the same supply used for the micro-controller

•

connect the digital IOs directly to the micro-controller DIOs

At any time, VBAT_IO must be lower than or equal to VBAT.

Figure 5-3: Separate DIO Supply

Table 5-3: Recommended 15 μH Inductors

Reference

Manufacturer

Value

(μH)

Idc max

(mA)

Freq

(MHz)

DCR

(ohm)

Package

(L x W x H in mm)

LPS3010-153

Coilcraft

370

0.95

2.95 x 2.95 x 0.9

MLZ2012N150L

TDK

0.47

2 x 1.25 x 1.25

MLZ2012M150W

TDK

120

0.95

2 x 1.25 x 1.25

VLS2010ET-150M

TDK

440

1.476

2 x 2 x 1

VLS2012ET-150M

TDK

440

1.062

2 x 2 x 1.2

Battery

Typ. 1.8 to 3.7 V

Controller

Regulator 1.8 V

Transceiver

VBAT_IO

VBAT

SPI

DIOx

NRESET

Requirement: VBAT ≥ VBAT_IO

LLCC68 Datasheet(PDF) 31 Page - Semtech Corporation

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