Datasheet ADP1822 (Analog Devices)

PWM, Step-Down DC-to-DC Controller with Margining and Tracking Data Sheet ADP1822 FEATURES
The ADP1822 regulated output can track another power supply
Wide power input voltage range: 1 V to 24 V
and can be dynamically adjusted up or down with the controller’s
Chip supply voltage range: 3.7 V to 5.5 V
margining-control inputs, making it ideal for high reliability
Wide output voltage range: 0.6 V to 85% of input voltage
applications. It is well suited for a wide range of high power
1% accuracy, 0.6 V reference voltage
applications, such as DSP power and processor core power in
Output voltage margining control
telecommunications, medical imaging, high performance
Output voltage tracking
servers, and industrial applications. It operates from a 3.7 V to
All N-channel MOSFET
5.5 V supply with power input voltage ranging from 1.0 V to 24 V.
300 kHz, 600 kHz, or up to 1.2 MHz synchronized frequency
The ADP1822 can operate at any frequency between 300 kHz
No current sense resistor required
and 1.2 MHz, either by synchronizing with an external source
Power-good output
or an internally generated, logic-controlled clock of 300 kHz or
Programmable soft start with reverse current protection
600 kHz. It includes an adjustable soft start to allow sequencing
Current-limit protection
and quick power-up while preventing input inrush current. Output
Thermal overload protection
reverse-current protection at startup prevents excessive output
Overvoltage protection
voltage excursions. The adjustable, virtually lossless current-
Undervoltage lockout
limit scheme reduces external part count and improves efficiency.
1 µA shutdown supply current
The ADP1822 operates over the −40°C to +125°C junction
Small, 24-lead QSOP package
temperature range and is available in a 24-lead QSOP package.
APPLICATIONS 97 Telecommunications and networking systems 96 High performance servers 3.3V OUTPUT 95 Medical imaging systems 94 DSP core power supplies 93 Microprocessor core power supplies 92 1.8V OUTPUT Mobile communication base stations Distributed power 91 EFFICIENCY (%) 90 GENERAL DESCRIPTION 89
The ADP1822 is a versatile and inexpensive synchronous voltage-
88
mode PWM step-down control er. It drives an al N-channel power
87
05311-006 stage to regulate an output voltage as low as 0.6 V.
0 2 4 6 8 10 12 14 16 LOAD CURRENT (A)
Figure 1. Efficiency vs. Load Current, 5 V Input
BIAS INPUT CMOSH-3 POWER INPUT 5V 2.25V TO 24V 10Ω 180µF 20V 1µF VCC PVCC BST 1µF 0.1µF IRF3711 DH ADP1822 1µH SW SHDN 6.18kΩ OUTPUT 1.8V, 15A CSL FREQ 1000µF IRF3711 4V DL SYNC 2.2pF PGND 20kΩ PWGD FB MAR TRKP MSEL 1nF 10kΩ TRKN 158kΩ COMP MDN SS MUP 80.6kΩ AGND DGND 15pF 316kΩ 309pF 100nF
001
TRACKING SIGNAL INPUT
05311- Figure 2. Typical Operating Circuit
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Document Outline Features Applications General Description Revision History Specifications Absolute Maximum Ratings ESD Caution Simplified Block Diagram Pin Configuration and Function Descriptions Typical Performance Characteristics Theory of Operation Current-Limit Scheme Output Voltage Margining Output Voltage Tracking Soft Start High-Side Driver (BST and DH) Low-Side Driver (DL) Input Voltage Range Setting the Output Voltage Switching Frequency Control Compensation Power-Good Indicator Shutdown Control Application Information Selecting the Input Capacitor Output LC Filter Selecting the MOSFETS Setting the Current Limit Feedback Voltage Divider Setting the Voltage Margin Compensating the Regulator Compensation Using the ESR Zero Compensation Using Feed-Forward Compensation Using Both the ESR and Feed-Forward Zeros Setting the Soft Start Period Synchronizing the Converter Setting the Output Voltage Tracking Application Circuits Outline Dimensions Ordering Guide