ADP3025 データシートの表示（PDF） - Analog Devices
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ADP3025 Datasheet PDF : 24 Pages
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ADP3025
C22
4.7µF
R14
4.7Ω
VIN 5.5V–25V
U1
C14A C14B
ADP3025
10µF
10µF
C18
1 CS5
BST5 38
C17
150pF
2 FB5
DRVH5 37
100nF
L2
6.8µH
R10
10kΩ
R1
130kΩ
C1
68pF
3 EAN5
SW5 36
D6
1N4148
Q5
SI4410
D2
10BQ040
D4
10BQ040
++
C27A
68µF
C27B
68µF
VOUT5
5V, 4A
4 EAO5
DRVL5 35
C2
330pF
5 ADJ/FX5
PGND1 34
C4
33nF
R2
200kΩ
6 SS5
7 CLSET5
SD 33
PGND2 32
C5
E 22nF
R3
200kΩ
8 REF
9 AGND
10 CLSET3
INTVCC1 31
VIN 30
DRVL3 29
R5
10Ω
T C6
33nF
11 INTVCC2
12 SYNC
13 SS3
SW3 28
D5
1N4148
DRVH3 27
BST3 26
E R4 C8
75kΩ 470pF
C9
L 68pF
14 ADJ/FX3
15 EAO3
16 EAN3
DRV2 25
FB2 24
COMP2/SD2 23
C19
330pF
R11
O 6.2kΩ
17 FB3
18 CS3
19 PFI
CPOR 22
PWRGD 21
PFO 20
R12
10kΩ
R13
10kΩ
R26
34.8kΩ
R24
200kΩ
Q4
SI4410
R27
10kΩ
C15
4.7µF
C13 C20A
1µF 10µF
C20B
10µF
Q2
C12 SI4410
100nF
Q3
SI4410
L1
6.8µH
D1
10BQ040
C10
47nF
PWRGD
PFO
D3
10BQ040
++
C24A
100µF
VOUT33
3.3V, 4A
C24B
100µF
C26
4.7µF Q1
IRF7403
R8
25.5kΩ
VOUT25
2.5V, 1.5A
C11
33µF
R9
49.9kΩ
C29
330pF
C28
33pF
R7
12kΩ
SFigure 17. 45 W, Triple Output DC-to-DC Converter
B MAXIMUM OUTPUT CURRENT AND MOSFET SELECTION
The maximum output current for each switching regulator is
limited by sensing the voltage drop between the drain and
O source of the high-side MOSFET when it is turned on. A
IPEAK
=
IOUT
+ VOUT
× ⎜⎜⎝⎛
VIN(MAX) − VOUT
2 × f × L ×VIN(MAX)
⎟⎟⎠⎞
(4)
current sense comparator senses voltage drop between CS5 and
SW5 for the 5 V converter and between CS3 and SW3 for the
3.3 V converter. The sense comparator threshold is 72 mV when
At a given current comparator threshold, VTH and MOSFET
RDS(ON), the maximum inductor peak current is
the programming pin CLSET is floating, and 300 mV when
IPEAK = VTH
(5)
CLSET is connected to ground. Current limiting is based on
RDS(ON )
sensing the peak current. Peak current varies with input voltage
and depends on the inductor value. The higher the ripple
Rearranging Equation 2 to solve for IOUT(MAX) gives
current or input voltage, the lower the converter maximum
output current at the set current sense amplifier threshold. The
relation between peak and dc output current is given by
IOUT ( MAX )
=
VTH
RDS(ON )
− VOUT
× ⎜⎜⎝⎛
VIN(MAX) − VOUT
2 × f × L ×VIN(MAX)
⎟⎟⎠⎞
(6)
VTH can be chosen to accommodate I . OUT(MAX)
Rev. A | Page 14 of 24
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