AAT2505 Analogic Corporation, AAT2505 Datasheet - Page 21

• Manufacturer Part Number: AAT2505
• Manufacturer: Analogic Corporation

1.8V Buck Input Capacitor
Input Ripple V
AAT2505 Total Losses
C
I
P = esr · I
P
T
2505.2006.06.1.1
RMS
J(MAX)
TOTAL
IN
=
=
⎛
⎝
=
+ (t
=
+ (5ns · 1.4MHz · 0.4A + 50µA +125µA) · 4.2V + (4.2V - 3.3V) · 0.3A = 395mW
= T
I
OBUCK
I
I
OBUCK
2
0.4
V
OBUCK
RMS
sw
AMB
PP
· F
2
2
= 0.2Arms
· (0.725 Ω · 1.8V + 0.7Ω · [4.2V - 1.8V])
+ Θ
PP
= 5mΩ · (0.2A)
2
S
· (R
- ESR · 4 · F
· I
= 25mV
JA
1
OBUCK
DSON(H)
· P
⎞
⎠
LOSS
+ I
· V
QBUCK
= 85°C + (50°C/W) · 395mW = 105°C
S
OBUCK
2
4.2V
= 0.2mW
=
+ I
⎛
⎝
+ R
QLDO
V
25mV
0.4A
IN
DSON(L)
) · V
IN
- 5mΩ · 4 · 1.4MHz
· [V
+ (V
IN
IN
⎞
⎠
- V
1
- V
OBUCK
OLDO
] )
) · I
OLDO
= 4.75μF
Converter/Linear Regulator
Dual Channel, Step-Down
21