ADP1828 Three Output Voltages

Preliminary Technical Data
ADP1828 Reference Design
FCDC 00118
FEATURES
Three Output Voltages: 3.3 V, 2.5 V, 1.25 V
Output Current: 2.2 A, 3.9 A, 12.7 A
Input Voltage Range: 10.8 V – 13.2 V
Ripple 1-2% ppk of Output Voltage
Transient step ±3%, 25% max load
ADP1828 AND ADP1829 DESCRIPTION
This ADP1828 and ADP1829 reference design uses 10.8 V to 13.2 V for the input voltage. The output voltages and currents
are as follows:
•
VOUT1 = 3.3 V with a maximum output current of 2.2 A and ripple voltage of 40 mVpk-pk,
•
VOUT2 = 2.5 V with a maximum output current of 3.9 A and ripple voltage of 25 mVpk-pk,
•
VOUT3 = 1.25 V with a maximum output current of 12.7 A and ripple voltage of 15 mVpk-pk
Design criteria requires coincidental tracking of VOUT2 and VOUT3 with VOUT1 to guarantee that VOUT3 and VOUT2 do not
exceed nor drop 0.5 V below VOUT1 at start up. The transient response is 3% deviation due to 25% instantaneous load step.
The nominal switching frequency is synchronized to an external 300 kHz clock with a minimum pulse width of 200 ns.
Each output is assumed to have additional distributed output capacitance of at least 25 uF / A of maximum load current
comprised of ceramic or low ESR Tantalum and is stable with up to 50 uF / A of maximum load current.
Rev. 1
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owners. Reference designs are not authorized to be used in life support devices or
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©2008 Analog Devices, Inc. All rights reserved.
Preliminary Technical Data
FCDC 00118
TABLE OF COTENTS
Features....................................................................................................................................................................................................... 1
ADP1828 and ADP1829 Description .................................................................................................................................................... 1
Revision History........................................................................................................................................................................................ 2
General Description ................................................................................................................................................................................. 3
ADP1828................................................................................................................................................................................................ 3
ADP1829................................................................................................................................................................................................ 3
Schematic ................................................................................................................................................................................................... 4
Bill of Materials ......................................................................................................................................................................................... 6
Performance............................................................................................................................................................................................... 8
Notes: ........................................................................................................................................................................................................ 10
TABLE OF FIGURES
Figure 1.
Schematic VOUT1 and VOUT2 ................................................................................................................................................ 4
Figure 2.
Schematic VOUT3................................................................................................................................................................... 5
Figure 3.
Calculated Efficiency for VOUT1 ......................................................................................................................................... 8
Figure 4.
Calculated Efficiency for VOUT2 ......................................................................................................................................... 8
Figure 5.
Calculated Efficiency for VOUT3 ......................................................................................................................................... 9
REVISION HISTORY
4/30/2008—Revision 0: Initial Version
8/07/2008—Revision 1: Changed tracking resistors on VOUT2 and VOUT3. Added second source FETs and Inductors.
Rev. 1 | Page 2 of 10
Preliminary Technical Data
FCDC 00118
GENERAL DESCRIPTION
ADP1828
The ADP1828 is a versatile and synchronous PWM voltage mode buck controller. It drives an all N-channel power stage to
regulate an output voltage as low as 0.6 V to 85% of the input voltage and is sized to handle large MOSFETs for point-ofload regulators. The ADP1828 is ideal for a wide range of high power applications, such as DSP and processor core I/O
power, and general-purpose power in telecommunications, medical imaging, PC, gaming, and industrial applications. It
operates from input bias voltages of 3 V to 18 V with an internal LDO that generates a 5 V output for input bias voltages
greater than 5.5 V. The ADP1828 operates at a pin-selectable, fixed switching frequency of either 300 kHz or 600 kHz, or at
any frequency between 300 kHz and 600 kHz with a resistor. The switching frequency can also be synchronized to an
external clock up to 2× the part’s nominal oscillator frequency. The clock output can be used for synchronizing additional
ADP1828s (or the ADP1829 controllers), thus eliminating the need for an external clock source. The ADP1828 includes
soft start protection to limit any inrush current from the input supply during startup, reverse current protection during soft
start for a precharged output, as well as a unique adjustable lossless current-limit scheme utilizing external MOSFET
RDSON sensing. For applications requiring power-supply sequencing, the ADP1828 provides a tracking input that allows
the output voltage to track during startup, shutdown, and faults. The additional supervisory and control features include
thermal overload, undervoltage lockout, and power good. The ADP1828 operates over the −40°C to +125°C junction
temperature range and is available in a 20-lead QSOP
ADP1829
The ADP1829 is a versatile, dual output, interleaved, synchronous PWM buck controller that generates two independent
outputs from an input voltage of 2.9 V to 18 V. Each channel can be configured to provide output voltage from 0.6V to 85%
of the input voltage. The two channels operate 180° out of phase, which reduces the current stress on the input capacitor
and allows the use of a smaller and lower cost input capacitor.
The ADP1829 operates at a pin-selectable fixed switching frequency of either 300 kHz or 600 kHz. For some noise sensitive
applications, it can also be synchronized to an external clock to achieve switching frequency between 300 kHz and 1 MHz.
The switching frequency chosen is 300 kHz to get good efficiency over a wide range of input and output conditions.
The ADP1829 includes an adjustable soft start to limit input inrush current, voltage tracking for sequencing or DDR
termination, independent power-good output, and a power enable pin. It also provides current-limit and short-circuit
protection by sensing the voltage on the synchronous MOSFET.
Rev. 1 | Page 3 of 10
Preliminary Technical Data
FCDC 00118
SCHEMATIC
3.3V at 2.2A and 2.5V at 3.9A
Rf12
Rc11
2
3
4
5
Vo3V3
6
7
Rt2h
8
Rt2l
Rin1
Css1 Cbias1
1
U2clk
Cvcc1
Cc12
Rf11
Cc10
Cc11
12Vin
Enable
Rc12
32
31
30
29
CMP1 TRK1 SS1 VREG
FB1
28
27
26
25
IN LDO EN2 EN1
SD
POK1
U1
SYNC
FREQ
BST1
DH1
ADP1829ACPZ
GND
SW1
UV2
CSL1
FB2
PGND1
CMP2
DL1
TRK2
Cc20
PV
Rpg1
POK3V3
24
23
QH1
Cb1
Cin11
22
21
20
Rlim1
Db1
Clim1
Rpv1
18
Vo3V3
Csn1
Rsn1
19
17
Co11 Co12
L1
QL1
Cpv1
Cinb
QL2
SS2 POK2 BST2 DH2 SW2 CSL2 PGND2 DL2
9
10
11
12
13
14
15
16
Rsn2
Csn2
Rc21 Cc21
Clim2
Css2
Vo2V5
Db2
Rpg2
Rlim2
L2
Co21 Co22
POK2V5
Rf23
Rf22
Rc22
Rf21
Cb2
Cc22
Figure 1.
Schematic VOUT1 and VOUT2
Rev. 1 | Page 4 of 10
QH2
Cin21
Preliminary Technical Data
FCDC 00118
Figure 2.
Schematic VOUT3
Rev. 1 | Page 5 of 10
Preliminary Technical Data
FCDC 00118
BILL OF MATERIALS
Table 1. Bill of Materials
Description
Capacitor Ceramic X7R 1.2n 0603 50V
Designator
Cc12
Quantity
1
Manufacturer
Vishay
MFR#
Generic
Capacitor Ceramic COG 56p 0603 50V
Cc10, Cc20
2
Vishay
Generic
Capacitor Ceramic X7R 1.5n 0603 50V
Cc11 Cc21, Cc32
3
Vishay
Generic
Capacitor Ceramic X7R 1u 0603 16V
Cvcc1, Cvcc2, Cbias1,
Cbias2, Cpv1, Cpv2
6
Murata
GRM188R71C105KA12D
Capacitor Ceramic X7R 47n 0603 16V
Css1
1
Vishay
Generic
Capacitor Ceramic X7R 10u 1206 16V
Cin11, Cin21, Cin31
3
Murata
GRM31CR71C106KAC7L
Capacitor Ceramic X7R 10n 0603 16V
Css3, Css2
2
Vishay
Generic
Capacitor Ceramic X7R 100n 0603 16V
Cb1, Cb2, Cb3
3
Vishay
Generic
Capacitor Ceramic COG 33p 0603 50V
Clim1, Clim2, Clim3
3
Vishay
Generic
Capacitor Ceramic X7R 1.0n 0603 50V
Cc22
1
Vishay
Generic
Capacitor Ceramic X7R 1.2n 0603 50V
Cc31
1
Vishay
Generic
Capacitor Ceramic COG 47p 0603 50V
Cc30
1
Vishay
Generic
Capacitor Ceramic X5R 22u 1206 6.3V
Co11
1
Murata
grm31cr60j226k
Capacitor Ceramic X5R 47u 1206 6.3V
Co21, Co31
2
Murata
grm31cr60j476m
Diode Schottky 200mA SOD-323 40V
Db1, Db2, Db3
3
Inductor Ferrite 8.2uH 10.3mm x 10.5mm
L1
1
Inductor Ferrite 3.8uH 10.3mm x 10.5mm
L2
1
Inductor Ferrite 1uH 12.5mm x 12.5mm
L3
1
Single N-Channel MOSFET TSDSON-8 30V
QH1, QL1, QH2, QL2, QH3
5
Single N-Channel MOSFET TDSON-8 30V
QL3
1
Diodes inc
Coiltronics
Coilcraft
Coiltronics
Coilcraft
Coiltronics
Coilcraft
Infineon
Vishay
Infineon
Vishay
BAT54WS
DR104-8R2-R
MSS1038-702
DR104-3R8-R
MSS1038-382
DR125-1R0-R
MSS1260-102
BSZ088N03MS
Si7114DN
BSC020N03LS
Si7658DP
Single P-Channel MOSFET SOT-323 -50V
Qml
1
Diodes inc
BSS84W
Single N-Channel MOSFET SOT-323 60V
Qmh
1
Diodes inc
2N7002W
Zero Ohm Jumper 0603
Rfreq, Rf23
2
Vishay
Generic
5% Thick Film 10 Ohms 0603
Rin1, Rin2, Rpv1, Rpv2
4
Vishay
Generic
1% Thick Film 10.0k 0603
Rpg1, Rpg2, Rpg3
3
Vishay
Generic
1% Thick Film 20.0k 0603
Rf11, Rf21, Rt2h
3
Vishay
Generic
1% Thick Film 16.2k 0603
Rf31, Rt3h
2
Vishay
Generic
1% Thick Film 6.34k 0603
Rf22
1
Vishay
Generic
1% Thick Film 4.75k 0603
Rt2l
1
Vishay
Generic
1% Thick Film 15.0k 0603
Rf32
1
Vishay
Generic
1% Thick Film 22.1k 0603
Rt3l
1
Vishay
Generic
1% Thick Film 8.2k 0603
Rc31
1
Vishay
Generic
1% Thick Film 100 Ohms 0603
Rc12, Rc22, Rc32
3
Vishay
Generic
1% Thick Film 374k 0603
Rmh
1
Vishay
Generic
1% Thick Film 2.49Meg 0603
Rml
1
Vishay
Generic
1% Thick Film 1.54k 0603
Rlim3
1
Vishay
Generic
1% Thick Film 1.69k 0603
Rlim2
1
Vishay
Generic
1% Thick Film 1.10k 0603
Rlim1
1
Vishay
Generic
1% Thick Film 4.42k 0603
Rf12
1
Vishay
Generic
Rev. 1 | Page 6 of 10
Preliminary Technical Data
FCDC 00118
1% Thick Film 17.8k 0603
Rc11, Rc21
2
Vishay
Generic
2 chan 300k to 600k PWM LFCSP-32
U1
1
Analog Devices
ADP1829ACPZ
1 chan 300k to 600k PWM QSOP-20
U2
1
Analog Devices
ADP1828ARQZ
Rev. 1 | Page 7 of 10
Preliminary Technical Data
FCDC 00118
PERFORMANCE
Figure 3.
Calculated Efficiency for VOUT1
Figure 4.
Calculated Efficiency for VOUT2
Rev. 1 | Page 8 of 10
Preliminary Technical Data
FCDC 00118
Figure 5.
Calculated Efficiency for VOUT3
Rev. 1 | Page 9 of 10
Preliminary Technical Data
FCDC 00118
NOTES:
A reference designator shown on the schematic and not appearing in the Bill of Materials is considered a stuffing option
and is not populated.
If a different number, or different type of output capacitors are used on the switching outputs the loop compensation
components may need adjustment.
©2008 Analog Devices, Inc. All rights
reserved. Trademarks and registered
trademarks are the property of their
respective owners.
EB0561
Rev. 1 | Page 10 of 10
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