SD3112-4R7-R datasheet(18/22 Pages) SKYWORKS

18 / 22 page

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201999B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013

AAT1171

600mA Voltage-Scaling Step-Down Converter

for RF Power Amplifiers with Bypass Switch

DATA SHEET

PA Step-Down Converter Design Example

Specifications

VO(BUCK) 0.6V to 3.4V with RL =10Ω

VIN

2.7V to 4.2V (3.6V nominal)

2.0MHz

TAMB

85°C

Output Inductor

L1 = 2.2μH

For Copper Electronics SD3112, 2.2μH, DCR = 140mΩ.

2.1

2.1V

ΔIL1(MAX) =

⋅ 1 -

= 239mA

L ⋅ FS

VIN

2.2µH ⋅ 2.0MHz

4.2V

⎛

⎝

⎞

⎠

⎛

⎝

⎞

⎠

The maximum inductor ripple current occurs at 50% duty cycle at the maximum input voltage.

PKL1 = IO +

ΔIL1(MAX)

= 0.6A + 0.118A = 0.718A

L1 = IO

⋅ DCR = 0.6A2 ⋅ 140mΩ = 50mW

Output Capacitor

Specify that VDROOP = 0.2V for a 600mA load pulse.

3.4V · (4.2V - 3.4V)

4.7µH · 2.0MHz · 4.2V

RMS

L1 · FS · VIN(MAX)

3 · ΔILOAD

VDROOP · FS

3 · 0.6A

0.2V · 2.0MHz

COUT =

= 4.5µF

= 69mArms

(VO) · (VIN(MAX) - VO) =

PESR = ESR · IRMS2 = 5mΩ · (69mA)2 = 24µW

Input Capacitor

Specify a maximum input voltage ripple of VPP = 25mV.

CIN(MIN) =

= 3.4µF

⎛⎞

- ESR ·

4 · FS

⎝⎠

VPP

⎛⎞

- 5mΩ ·

4 · 2.0MHz

⎝⎠

25mV

0.6A

RMS

P = ESR · IRMS2 = 5mΩ · (0.3A)2 = 0.45mW

= 0.3Arms

SD3112-4R7-R Datasheet(PDF) 18 Page - Skyworks Solutions Inc.

SD3112-4R7-R Datasheet(HTML) 18 Page - Skyworks Solutions Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Datasheet Download

Link URL