8.2.2 Boost with Schottky Diode

Another typical application example is the USB OTG which normally requires 5-V output as its supply voltage

and consumes as high as 500-mA current. The following design procedure can be used to select external

component values for this application.

TPS613222A

Battery

SW

VOUT

22uF

2.2uH

VOUT

5.0V, 500mA

GND

L1

C1

D1

C2

R1

Figure 8-9. Typical Application Circuit with Schottky Diode

8.2.2.1 Design Requirements

Table 8-4. Design Requirements

PARAMETERS

VALUES

Input voltage

3 V to 4.35 V

Output voltage

5 V

Output vurrent

500 mA

Output voltage ripple

± 25 mV

8.2.2.2 Detailed Design Procedure

8.2.2.2.1 Inductor Selection

The peak current is calculated according to Equation 4 and Equation 5.The saturation current of the inductor

must be higher than the calculated peak inductor current.

In this example, the maximum load for the boost converter is 500 mA, and the minimum input voltage is 3 V.

Assuming the efficiency under this condition is 90%, and a typical 2.2-µH inductor is adopted in this application,

so the boost converter works in continuous operation mode by the calculation. The current ripple is 500mA

and the inductor peak current is calculated as 1.18 A. To leave some margin, a 2.2-µH inductor with at least

1.4-A saturation current is recommended for this application.Table 8-5 lists the recommended inductors for

TPS613222A device.

Table 8-5. List of Inductors

INDUCTAN

CE [µH]

SATURATION CURRENT

[A]

DC

RESISTANC

E [mΩ]

SIZE (L×W×H) (mm)

PART NUMBER

MANUFACTURER(1)

2.2

2.3

82

2.5 × 2 × 1.2

DFE252012F-2R2M

MURATA

2.2

2.4

89

2.5 × 2 × 1

HMLQ25201T-2R2MSR

CYNTEC

2.2

2.5

75

3.2 × 2.5 × 1.2

HMME32251B--2R2MS

CYNTEC

(1)

See Third-party Products Disclaimer

TPS61322

SLVSDY5E – JANUARY 2018 – REVISED FEBRUARY 2024

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