Data Sheet

ADPL76030

analog.com

Rev.0

27 of 40

where:

∆IL% =

∆IL

IL(AVG)

f is the switching frequency.

VIN(MIN) is the minimum input voltage.

VIN(MAX) is the maximum input voltage.

VOUT is the output voltage.

IOUT(MAX)is the maximum output current.

Slope compensation provides stability in constant frequency current-mode control by preventing subharmonic

oscillations at certain duty cycles. The minimum inductance required for stability when duty cycles are larger than

50% can be calculated as:

L >

10 × VOUT × RSENSE

f

For high efficiency, choose an inductor with low core loss, such as ferrite. Also, the inductor should have low DC

resistance to reduce the I2R losses, and must be able to handle the peak inductor current without saturating. To

minimize radiated noise, use a shielded inductor.

R

SENSE Selection and Maximum Output Current

RSENSE is chosen based on the required output current. The duty cycle independent maximum current-sense

thresholds (50 mV in peak-buck and 50 mV in peak-boost) set the maximum inductor peak current in buck region,

buck-boost region, and boost region.

In boost region, the lowest maximum average load current happens at VIN(MIN)and can be calculated as:

IOUT(MAX_BOOST) = (

50 mV

RSENSE

−

∆IL(BOOST)

2

)

×

VIN(MIN)

VOUT

where, ∆IL(BOOST) is the peak-to-peak inductor ripple current in boost region, and can be calculated as:

∆IL(BOOST) =

VIN(MIN) × (VOUT − VIN(MIN))

f

× L × VOUT

In buck region, the lowest maximum average load current happens at VIN(MAX), and can be calculated as:

IOUT(MAX_BUCK) = (

50 mV

RSENSE

−

∆IL(BUCK)

2

)

where, ∆IL(BUCK)is peak-to-peak inductor ripple current in buck region and can be calculated as:

∆IL(BUCK) =

VOUT × (VIN(MAX) − VOUT)

f

× L × VIN(MAX)

The maximum current sense RSENSE in the boost region is: