The ADP1821 is a versatile and inexpensive, synchronous, pulse-width-modulated (PWM), voltage-mode, step-down controller. It drives an all N-channel power stage to regulate an output voltage as low as 0.6 V. The ADP1821 can be configured to provide output voltages from 0.6 V to 85% of the input voltage and is sized to handle large MOSFETs for point-of-load regulators.

The ADP1821 is well suited for a wide range of high power applications, such as DSP and processor core power in telecommunications, medical imaging, high performance servers, and industrial applications. It operates from a 3.7 V to 5.5 V supply with a power input voltage ranging from 1.0 V to 24 V.

The ADP1821 operates at a pin-selectable, fixed switching frequency of either 300 kHz or 600 kHz, minimizing external component size and cost. For noise sensitive applications, it can be synchronized to an external clock to achieve switching frequencies between 300 kHz and 1.2 MHz. The ADP1821 includes soft start protection to limit the inrush current from the input supply during startup, reverse current protection during soft start for precharged outputs, as well as a unique adjustable lossless current-limit scheme utilizing external MOSFET sensing.

The ADP1821 operates over the –40°C to +125°C junction temperature range and is available in a 16-lead QSOP.

Applications

Telecommunications and networking systems

Set-top boxes

Printers

Servers

Medical imaging systems

Microprocessor and DSP core power supplies

Mobile communication base stations

Data Sheet, Rev. C, 4/07

Part#	Vin Range	Pwr Stage Vin	Vout Adj Options	Multi-Output	Shutdown Current	Supply Current (max)	Switching Frequency	Iout (max)	Synchronous	Step Down	Step Up	Pkg	Product Description	Price* (1000-4999)
ADP1621	2.9V-5.5V	As Low As 1V	Lossless ISens@<30V Vout, Resistor ISens@>30V	No	10µA	3mA	100 KHz - 1.5 MHz	-	No	No	Yes	MSOP-10	Constant-Frequency, Current-Mode, Step-Up DC/DC Controller	$1.30
ADP1821	3.7V-5.5V	1V-24V	0.6V to 85% PwrStgVin	No	10µA	2mA	300 kHz -600 kHz, Sync up to 1 MHz	20A	Yes	Yes	No	QSOP-16	20 A Step-Down DC-DC Controller	$1.35
ADP1822	3.7V-5.5V	1V-24V	0.6V to 85% PwrStgVin	No	10µA	2mA	300 kHz-600 kHz; Sync up to 1 MHz	20A	Yes	Yes	No	QSOP-24	20 A, PWM, Step-Down DC-DC Controller with Margining and Tracking	$1.40
ADP1823	3.7V-20V	1V-24V	0.6V to 85% PwrStgVin	Yes	20µA	3mA	300 kHz-600 kHz, Sync up to 1 MHz	20A	Yes	Yes	No	LFCSP-32	Versatile Dual, Interleaved Synchronous PWM Buck Controller w/ Tracking	$2.10
ADP1828	3.0V-18V	1V-24V	0.6V to 85% PwrStgVin	No	15µA	3mA	300 kHz to 600 kHz	-	Yes	Yes	No	QSOP-20	Synchronous Buck PWM, Step-Down, DC-to-DC Controller	$1.50
ADP1829	3.0V-18V	1V-24V	0.6V to 85% PwrStgVin	Yes	20µA	3mA	300 kHz-600 kHz, Sync up to 1 MHz	20A	Yes	Yes	-	LFCSP-32	Dual, Interleaved, Step-Down DC-to-DC Controller w/ Tracking	$2.10
ADP1864	3.15V-14V	3.15V-14V	0.8V to Vin	No	15µA	350µA	580 kHz	5A	No	Yes	No	TSOT-6	5A, Constant Frequency, Current-Mode Step-Down DC/DC Controller in TSOT	$1.05

* The pricing listed here is provided only for budgetary purposes as recommended list price in U.S. Dollars in the United States ex factor per unit for the stated volume. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
** Pricing is currently unavailable. Click on the product number to see the Product Page for additional information.

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Pin Count is the number of pins, balls, or pads on the device. Pin-out diagrams & pin function descriptions may be found in the datasheet.

This is the acceptable operating range of the device. The various ranges specified are as follows:

• Commercial: 0 to +70 degrees Celsius
• Military : -55 to +125 degrees Celsius
• Industrial: Temperature ranges may vary by model. Please consult the datasheet for more information.
• Automotive: -40 to +125 degrees Celsius

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