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 Reference designs are as supplied “as is” and without warranties of any kind, express, implied, or statutory including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose. No license is granted by implication or otherwise under any patents or other intellectual property by application or use of reference designs. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Analog Devices reserves the right to change devices or specifications at any time without notice. Trademarks and registered trademarks are the property of their respective owners. Reference designs are not authorized to be used in life support devices or systems. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©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