Power and Thermal Management ICs
Volume 8, Issue 6 YOUR SEMICONDUCTOR SOLUTIONS RESOURCE

C o n t e n t s

On-Board Oscillators Synchronize Other Regulators to Reduce the Number of Beat Frequencies >>

DC-to-DC Controller Provides Steady Voltage >>

Industry's Highest Accuracy (±0.8%) Voltage Sequencers and Supervisors >>

Voltage Sequencers and Supervisors Selection Tables >>

Precision Voltage References for Lower Current Applications >>

Accurate Hot Swap Controllers with Integrated Digital Power Monitors >>

New Digital Controller Increases Efficiency and Accelerates Time to Market >>

Temperature Control Independent of the Microprocessor >>

Reduce Space Requirements for Isolated DC-to-DC Power Supply >>

Improve Conversion Efficiency and Optimize Performance for Low Output Voltages >>

Regulator Circuit Design Made Easy with ADI's New Online Tool >>

AVNET

All prices in this bulletin are in USD in quantities greater than 1000 (unless otherwise noted), recommended lowest grade resale, FOB U.S.A.

Analog is Everywhere

Analog Devices
On-Board Oscillators Synchronize Other Regulators to Reduce the Number of Beat Frequencies

Many systems are highly sensitive to noise and beat frequencies. When using switching regulators, this challenge is typically amplified by the fact that each regulator is running at a different frequency, thus generating a number of beat frequencies that are difficult to filter out. One approach to overcome this challenge is to run all switching regulators at the same switching frequency. However, to achieve this solution, all regulators need to be synchronized to the same oscillator. Rather than requiring placement of an oscillator circuit on a board, the oscillator output of ADI's ADP1828 dc-to-dc controller can be used to synchronize other controllers. The switching frequency is user programmable from 300 kHz to 600 kHz with a single resistor. The synchronization output frequency can be phase shifted 180° to reduce the size of input capacitors or it can be doubled with a pin setting to provide the 2× frequency that some switches require.

ADP1828

ADP1828 Features
• Wide supply range: 3 V to 18 V
• Oscillator frequency output to allow synchronization to other controllers
• Accuracy over temperature: ±0.85%
• Efficiency: up to 95%
• Shutdown current: 15 µA

Part
Number		 VIN
Range (V)		 VOUT Adjustability
Options (V)		 IOUT
Max (A)		 Switch
Freq		 Package Price
($U.S.)
ADP18211 3.7 to 5.5 0.6 to 0.85 VIN 20 600 kHz2 16-lead QSOP 1.35
ADP18221 3.7 to 5.5 0.6 to 0.85 VIN 20 600 kHz2 24-lead QSOP 1.40
ADP18281 3 to 18 0.6 to 0.85 VIN 20 600 kHz2 20-lead QSOP 1.50
ADP18291 3 to 18 0.6 to 17 20 600 kHz2 32-lead LFCSP 2.10
ADP18641 3.15 to 14 0.8 to VIN 5 580 kHz 6-lead TSOT 1.05
ADP21023 2.7 to 5.5 0.8 to 1.2, 1.2 to 1.5,
1.5 to 1.8, 2.5 to 3.3		 0.6 3 MHz 8-lead LFCSP 1.47
ADP21053 2.7 to 5.5 0.8 to VIN 1 1.2 MHz 16-lead LFCSP 1.13
ADP21063 2.7 to 5.5 0.8 to VIN 1.5 1.2 MHz 16-lead LFCSP 1.25
ADP21073 2.7 to 5.5 0.8 to VIN 2 1.2 MHz 16-lead LFCSP 1.32
ADP30503 3.6 to 30 — 1.5 200 kHz 8-lead SOIC 1.78

1Step-down type.
2From 300 kHz to 600 kHz, synchronization up to 1 MHz.
3Buck type.

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