ADP1649ACBZ-R7 datasheet(26/28 Pages) AD

Il numero della parte	ADP1649ACBZ-R7

Spiegazioni elettronici	1.0 A LED Flash Driver with I2C-Compatible Interface

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ADP1649

Data Sheet

Rev. 0 | Page 26 of 28

The worst-case capacitance accounting for capacitor variation

over temperature, component tolerance, and voltage is calcu-

lated using the following equation:

CEFF = COUT × (1 − TEMPCO) × (1 − TOL)

where:

CEFF is the effective capacitance at the operating voltage.

TEMPCO is the worst-case capacitor temperature coefficient.

TOL is the worst-case component tolerance.

In this example, the 10 μF X5R capacitor has the following

characteristics:

• TEMPCO from −40°C to +85°C is 15%.

• TOL is 10%.

• C

OUT at VOUT (max) = 5 V, is 3 μF, as shown in Figure 41.

Figure 41. DC Bias Characteristic of a 6.3 V, 10 μF Ceramic Capacitor

Substituting these values in the equation yields

CEFF = 3 μF × (1 − 0.15) × (1 − 0.1) = 2.3 μF

The effective capacitance needed for stability, which includes

temperature and dc bias effects, is 3.0 μF.

–10

–20

–30

–40

–50

–60

–70

–80

–90

6.30

5.04

3.78

2.52

DC BIAS VOLTAGE (V)

1.26

ADP1649ACBZ-R7 Scheda tecnica(PDF) 26 Page - Analog Devices