LXDC3EP33F-204 데이터 시트보기 (PDF) - Murata Manufacturing

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LXDC3EP33F-204

Micro DC-DC converter

Murata Manufacturing 

LXDC3EP TypeF series

Micro DC-DC converter

MLCC capacitor’s reliability and the lifetime is also dependant on temperature and applied voltage stress. Higher

temperature and/or higher voltage cause shorter lifetime of MLCC, and the degradation can be described by the

Arrhenius model. The most critical parameter of the degradation is IR (Insulation Resistance).

The below figure shows MLCC’s B1 life based on a failure rate reaching 1%. It should be noted that wear-out

mechanisms in MLCC capacitor is not reversible but cumulative over time.

Capacitor Case temperature( )

The following steps should be taken before the design fix of user’s set for a reliable operation.

1. The ambient temperature of the device should be kept below 85 oC

2. The case temperature should be measured on the worst condition of each application. The temperature must

be kept below 125 oC. An appropriate de-rating of temperature and/or output current should be taken.

3. The MLCC temperature should be considered as same as the case temperature. Considering the above

figure, it should be checked if the expected B1 life of MLCC is acceptable or not.

7. Detailed Description

Power-Save Mode / Forced PWM Mode

The MODE pin allows selecting the operating mode. If the MODE pin is pulled to logic low voltage (MODE-L), the

converter operates automatic pulse-skip and PWM mode. In this mode, the converter operates pulse-skip mode

at light load current, and when the load current increases, the operating mode will changes to PWM mode

automatically. In this mode, the converter can work in high efficiency over wide load current range. The transition

current between PFM and PWM is depend on Vin, Vout and other factors, but the ballpark threshold is about 50-

200mA

If the MODE pin is pulled to logic high voltage (MODE-H), the device operates in Forced PWM mode. In this mode,

the converter operates in PWM mode even at light load current. The advantage of this mode is that the converter

6

February 2016

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