ADP1621ARMZ-R7(RevB) View Datasheet(PDF) - Analog Devices
Part Name
Description
Manufacturer
ADP1621ARMZ-R7 Datasheet PDF : 32 Pages
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Data Sheet
ADP1621
SEPIC CONVERTER CIRCUIT
A single-ended primary inductance converter (SEPIC) topology
is shown in Figure 39. This topology is useful for an unregulated
input voltage, where the regulated output voltage falls within the
input voltage range.
The input and output are dc-isolated by a coupling capacitor,
C5. L1 and L2 are coupled inductors with a 1:1 turn ratio, which
saves space on the PCB. In steady state, the average voltage across
C5 is the input voltage. When the MOSFET turns on and the
diode turns off, the input voltage provides energy to L1, and C5
provides energy to L2. The output capacitor, COUT, supplies the
load current during this time. When the MOSFET turns off and
the diode turns on, the energy in L1 and L2 is released to charge
the output capacitor, COUT, and the coupling capacitor, C5, as
well as to supply current to the load.
LOW VOLTAGE POWER-INPUT CIRCUIT
The ADP1621 can be configured to run from a low voltage
(as low as 1 V) power input. The power source generally needs
to have a high current capability, such as a fuel cell. Figure 40
illustrates such an application, where the voltage of the power
input is 1 V and the voltage of the chip supply to the IN and
PIN pins is provided by an auxiliary low power source.
C3
1µF
10V
C2
33pF
VIN = 3V TO 5.5V
L2
2.4µH
D1
VOUT = 3.3V
2A
C4
0.1µF
10V
RCOMP
26kΩ
CCOMP
1.2nF
PIN IN
CS
ADP1621
SDSN
GATE
COMP PGND
FREQ
FB
GND
RFREQ
65kΩ
L1
2.4µH
RS
80Ω
C5
10µF
10V
M1 X5R
R1
17.4kΩ
1%
R2
10kΩ
1%
COUT1
1µF
10V
C1
22µF
10V
×2
COUT2
150µF
6.3V
×3
AGND
fOSC = 325kHz
C1 = MURATA GRM332ER61A226K
M1 = VISHAY Si7882DP
COUT2 = SANYO POSCAP 6TPE150MI D1 = VISHAY SSC53L
C5 = MURATA GRM21BR61A106K
L1, L2 = COUPLED INDUCTORS, 1:1 RATIO, BH ELECTRONICS BH510-1006
Figure 39. A SEPIC DC/DC Converter
VIN = 1V
C3
1µF
10V
C2
260pF
VCC = 2.9V TO 5.5V
C4
0.1µF
10V
PIN IN
RCOMP
9.4kΩ
CCOMP
56nF
CS
ADP1621
SDSN
GATE
COMP PGND
FREQ
FB
GND
RFREQ
31.6kΩ
1%
L1
2.2µH
D1
RS
249Ω
R1
35.7kΩ
1%
R2
11.5kΩ
M1
1%
COUT1
1µF
10V
VOUT = 5V
1A
COUT2
10µF
6.3V
COUT3
150µF
6.3V
×2
C1
100µF
X5R
6.3V
AGND
fOSC = 600kHz
C1 = MURATA GRM32ER60J107ME20
COUT2 = MURATA GRM21BR60J106K
COUT3 = SANYO POSCAP 6TPE150MI
M1 = VISHAY Si7882DP
D1 = MBRD835L
L1 = TOKO FDV0630-2R2M
Figure 40. Low Voltage Power-Input Application Circuit
Rev. B | Page 27 of 32
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