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Synchronous Buck PWM, Step-Down, DC-to-DC Controller ADP1828
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FEATURES
Wide bias voltage range 3.0 V to 18 V Wide power stage input range 1 V to 24 V Wide output voltage range: 0.6 V to 85% of input voltage ±0.85% accuracy at 0oC to 70oC All N-channel MOSFET design for low cost Fixed-frequency operation at 300 kHz, 600 kHz, or resistor adjustable 300 kHz to 600 kHz Clock output for synchronizing other controllers No current sense resistor required Internal linear regulator Voltage tracking for sequencing Soft start and thermal overload protection Overvoltage and undervoltage power-good indicator 15 μA shutdown supply current Available in a 20-lead QSOP
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-of-load 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.
VIN = 10V TO 18V CIN 180µF ×2 20V D1 C4 0.47µF RCL 1.8kΩ
APPLICATIONS
Telecom and networking systems Base station power Set-top boxes, game consoles Printers and copiers Medical imaging systems DSP and microprocessor core power supplies DDR termination
GENERAL DESCRIPTION
The ADP1828 is a versatile and synchronous PWM voltage mode buck controller. It drives an all N-channel power stage
C5 1µF VREG IN R6 100kΩ C6 1µF EN FREQ SYNC PGOOD COMP C2 33pF R8 20kΩ C3 5.6nF CSS 200nF SS PV
C7 1µF TRK BST DH SW CSL DL PGND FB CLKOUT CLKSET GND AGND
ADP1828
M1 L1 = 0.82µH M2 ×2 COUT2 1000µF ×2
OUTPUT 1.8V, 20A COUT1 R3 47µF 7.5kΩ X5R C1 6.3V R1 20kΩ 680pF R2 10kΩ
AGND PGND
fSW = 300kHz CIN: SANYO, OSCON 20SP180M COUT2: SANYO, POSCAP 2R5TPD1000M5 L1: WURTH ELEKTRONIC, 0.82µH, 744355182
Figure 1. Typical Application Circuit with 20 A Output
Rev. 0
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06865-001
D1: BAT54 M1: INFINEON, BSC080N03LS M2: INFINEON, 2 × BSC030N03LS
ADP1828 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 6 ESD Caution .................................................................................. 6 Simplified Block Diagram ............................................................... 7 Pin Configuration and Function Descriptions ............................. 8 Typical Performance Characteristics ............................................. 9 Theory of Operation ...................................................................... 14 Input Power ...........................................