Datasheet

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TEMPRISE LOAD PEAK LOAD

I = I + D I I = 1.5A + 0.2 × 2.5A 1 .5A = 1.7A´ - -

RIPPP LE

PEAK LOAD(MAX)

I = I 1+

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bq24160, bq24160A

bq24161, bq24161B

bq24163, bq24168

SLUSAO0E –NOVEMBER 2011–REVISED NOVEMBER 2013

www.ti.com

APPLICATION INFORMATION

Output Inductor and Capacitor Selection Guidelines

When selecting an inductor, several attributes must be examined to find the right part for the application. First,

the inductance value should be selected. The bq2416x is designed to work with 1.5µH to 2.2µH inductors. The

chosen value will have an effect on efficiency and package size. Due to the smaller current ripple, some

efficiency gain is reached using the 2.2µH inductor, however, due to the physical size of the inductor, this may

not be a viable option. The 1.5µH inductor provides a good tradeoff between size and efficiency.

Once the inductance has been selected, the peak current must be calculated in order to choose the current

rating of the inductor. Use Equation 5 to calculate the peak current.

(5)

The inductor selected must have a saturation current rating greater than or equal to the calculated I

PEAK

. Due to

the high currents possible with the bq2416x, a thermal analysis must also be done for the inductor. Many

inductors have a 40°C temperature-rise rating. The DC component of the current can cause a 40°C temperature

rise above the ambient temperature in the inductor. For this analysis, the typical load current may be used

adjusted for the duty cycle of the load transients. For example, if the application requires a 1.5A DC load with

peaks at 2.5A 20% of the time, a Δ40°C temperature rise current must be greater than 1.7A:

(6)

The bq2416x provides internal loop compensation. Using this scheme, the bq2416x is stable with 10µ F to 200µF

of local capacitance on the SYS output. The capacitance on the SYS rail can be higher if distributed amongst the

rail. To reduce the output voltage ripple, a ceramic capacitor with the capacitance between 10µF and 47µF is

recommended for local bypass to SYS. A 47µF bypass capacitor is recommended for optimal transient response.

Product Folder Links: bq24160 bq24160A bq24161 bq24161B bq24163 bq24168