AAT1112IWP-0.6-T1 View Datasheet(PDF) - Analog Technology Inc

Part Name

Description

MFG CO.

AAT1112IWP-0.6-T1

1.5A, 1.4MHz Step-Down Converter

Analog Technology Inc 

AAT1112

1.5A, 1.4MHz Step-Down Converter

Input Capacitor

Input Ripple VPP = 50mV

1

1

CIN =

⎛

⎝

VPP -

IO1 + IO2

ESR⎞⎠

·

4

·

FS

=

⎛ 50mV

⎝ 1.5A

= 7.3µF; use 10µF

- 5mΩ⎞⎠ · 4 · 1.2MHz

I = RMS(MAX)

IO

2

= 0.75Arms

P = esr · IRMS2 = 5mΩ · (0.75A)2 = 3mW

AAT1112 Losses

Total losses can be estimated by calculating the dropout (VIN = VO) losses where the power MOSFET RDS(ON)

will be at the maximum value. All values assume an 85°C ambient temperature and a 120°C junction temper-

ature with the TDFN 50°C/W package.

PLOSS = IO12 · RDS(ON)H = 1.5A2 · 0.16Ω = 0.36W

TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 360mW = 103°C

The total losses are also investigated at the nominal lithium-ion battery voltage (3.6V). The simplified version

of the RDS(ON) losses assumes that the N-channel and P-channel RDS(ON) are equal.

PTOTAL = IO2 · RDS(ON) + (tsw · FS · IO + IQ) · VIN

= 1.5A2 · 152mΩ + (5ns · 1.2MHz · 1.5A + 50μA) · 3.6V = 375mW

TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 375mW = 104°C

1112.2007.01.1.1

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