The ADP1870/ADP1871 are versatile current-mode, synchronous step-down controllers that provide superior transient response, optimal stability, and current-limit protection by using a constant on-time, pseudo-fixed frequency with a programmable currentlimit, current-control scheme. In addition, these devices offer optimum performance at low duty cycles by utilizing valley current-mode control architecture. This allows the ADP1870/ ADP1871 to drive all N-channel power stages to regulate output voltages as low as 0.6 V.
The ADP1871 is the power saving mode (PSM) version of the device and is capable of pulse skipping to maintain output regulation while achieving improved system efficiency at light loads (see the Power Saving Mode (PSM) Version (ADP1871) section for more information).
Available in three frequency options (300 kHz, 600 kHz, and 1.0 MHz, plus the PSM option), the ADP1870/ADP1871 are well suited for a wide range of applications that require a single-input power supply range from 2.95 V to 20 V. Low voltage biasing is supplied via a 5 V internal LDO.
In addition, an internally fixed soft start period is included to limit input in-rush current from the input supply during startup and to provide reverse current protection during soft start for a precharged output. The low-side current-sense, current-gain scheme and integration of a boost diode, along with the PSM/forced pulsewidth modulation (PWM) option, reduce the external part count and improve efficiency.
The ADP1870/ADP1871 operate over the -40°C to +125°C junction temperature range and are available in 10-lead MSOP package.
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|ADP1870/ADP1871: Synchronous Buck Controller with Constant On-Time and Valley Current Mode Data Sheet (Rev B, 07/2012) (pdf, 1861 kB)||Data Sheets|
AN-1075: Synchronous Inverse SEPIC Using the ADP1870/ADP1872 Provides High Efficiency for Noninverting Buck/Boost Applications
(pdf, 167 kB)
Discusses using the ADP1870/ADP1872 as an inverse single-ended primary inductor converter (SEPIC), also known as the Zeta converter, that can operate in either buck or boost mode, decreasing or increasing the input voltage to a desired regulated voltage, with minimal cost, component count, and power loss.
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|Glossary of EE Terms||Glossary||HTML|
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ADP187x Buck Designer Tool
Microsoft Excel download tool from ADIsimPower to generate a power supply design complete with a schematic, bill of materials, and performance specifications.
|ADIsim Design/Simulation Tools||ZIP|
Download files for ADIsimPower™ Voltage Regulator Design Tool
The individual Excel-based voltage regulator design tools used in ADIsimPower™.
|ADIsim Design/Simulation Tools||HTML|
Blank/Unpopulated boards need to be ordered through the appropriate download tool from ADIsimPower.
ADP1870 Evaluation Board
Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.