AAT2689 Analogic Corporation, AAT2689 Datasheet - Page 17

• Manufacturer Part Number: AAT2689
• Manufacturer: Analogic Corporation

AAT2689 Design Example
Specifications
V
V
V
F
T
Channel 1 Output Inductor
For Sumida inductor RCH108NP-4R7M, 4.7μH, DCR = 11.7mΩ max.
ΔI =
Channel 1 Output Capacitor
V
C
I
Channel 1 Input Capacitor
Input Ripple V
C
For low cost applications, 100μF/25V electrolytic capacitor in parallel with 1μF/25V ceramic capacitor are used to reduce
the ESR.
I
P = ESR · ( I
P
P
SystemPower
SystemPower
I
2689.2008.06.1.0
2689.2008.06.1.0
RMS(MAX)
RMS
PK1
S
AMB
O1
O2
IN1
DROOP
L1
OUT
RMS
IN1
= 490kHz
= I
= 3.3V @ 2.5A, Pulsed Load ΔI
= 1.8V @ 600mA
= I
=
= 12V
=
L
= 85°C in TDFN34-16 Package
V
= ESR · I
=
1
OUT1
I
OUT1
OUT1
= 0.33V (10% Output Voltage)
OUT1
· F
V
V
I
=
2
OUT1
3 · ΔI
DROOP
PP1
S
2
2
+
·
· DCR = 3.5A
· 1 -
1
= 1.25A
RMS
- ESR · 4 · F
ΔI
LOAD
2
3
RMS
TM
TM
· F
PP
)
·
2
= 2.5A + 1A = 3.5A
2
= 25mV
V
S
V
1
= 5mΩ · (1.25A)
PMIC Solution for 12V Adapter Systems with 2-Output High Performance Step-Down Converters
PMIC Solution for 12V Adapter Systems with 2-Output High Performance Step-Down Converters
V
= 11.7mΩ · (357mA)
OUT1
OUT1
=
IN
L · F
0.33V · 490kHz
· (V
=
2
S
3 · 2.5A
S
4.7μH · 490kHz
IN(MAX)
· 11.7mΩ = 143mW
· V
=
IN1(MAX)
3.3V
- V
25mV
2.5A
2
= 7.8mW
OUT1
LOAD
= 46.4μF; use 2x22μF
2
)
- 5mΩ · 4 · 490kHz
= 1.5W
=
= 2.5A
2
· 1 -
·
1
1
3
·
w w w . a n a l o g i c t e c h . c o m
w w w . a n a l o g i c t e c h . c o m
3.3V
12V
4.7μH · 490kHz · 24V
3.3V · (24V - 3.3V)
= 1A
= 102μF
= 357mA
RMS
PRODUCT DATASHEET
PRODUCT DATASHEET
AAT2689
AAT2689
17
17