Datasheet ADP1828 (Analog Devices)

Synchronous Buck PWM, Step-Down, DC-to-DC Controller Data Sheet ADP1828 FEATURES
to regulate an output voltage as low as 0.6 V to 85% of the input
Wide bias voltage range 3.0 V to 20 V
voltage and is sized to handle large MOSFETs for point-of-load
Wide power stage input range 1 V to 24 V
regulators. The ADP1828 is ideal for a wide range of high power
Wide output voltage range: 0.6 V to 85% of input voltage
applications, such as DSP and processor core I/O power, and
±0.85% accuracy at 0oC to 70oC
general-purpose power in telecommunications, medical imaging,
All N-channel MOSFET design for low cost
PC, gaming, and industrial applications. It operates from input
Fixed-frequency operation at 300 kHz, 600 kHz, or resistor
bias voltages of 3 V to 20 V with an internal LDO that generates
adjustable 300 kHz to 600 kHz
a 5 V output for input bias voltages greater than 5.5 V.
Clock output for synchronizing other controllers
The ADP1828 operates at a pin-selectable, fixed switching
No current sense resistor required
frequency of either 300 kHz or 600 kHz, or at any frequency
Internal linear regulator
between 300 kHz and 600 kHz with a resistor. The switching
Voltage tracking for sequencing
frequency can also be synchronized to an external clock up to
Soft start and thermal overload protection
2× the nominal oscillator frequency of the device The clock
Overvoltage and undervoltage power-good indicator
output can e used for synchronizing additional ADP1828s (or
15 μA shutdown supply current
the ADP1829 controllers), thus eliminating the need for an
Available in a 20-lead QSOP and 20-lead, 4 mm × 4 mm LFCSP
external clock source. The ADP1828 includes soft start protection
APPLICATIONS
to limit any inrush current from the input supply during startup, reverse current protection during soft start for a precharged
Telecom and networking systems
output, as well as a unique adjustable lossless current-limit
Base station power
scheme utilizing external MOSFET RDSON sensing.
Set-top boxes, game consoles Printers and copiers
For applications requiring power-supply sequencing, the ADP1828
Medical imaging systems
provides a tracking input that allows the output voltage to track
DSP and microprocessor core power supplies
during startup, shutdown, and faults. The additional supervisory
DDR termination
and control features include thermal overload, undervoltage lockout, and power good.
GENERAL DESCRIPTION
The ADP1828 operates over the −40°C to +125°C junction temper- The ADP1828 is a versatile and synchronous PWM voltage ature range and is available in a 20-lead QSOP and 20-lead, 4 mm × mode buck controller. It drives an all N-channel power stage 4 mm LFCSP.
VIN = 10V TO 18V CIN 180µF C7 ×2 C5 1µF 20V 1µF D1 VREG PV TRK BST C4 0.47µF IN M1 DH ADP1828 OUTPUT L1 = 0.82µH 1.8V, 20A C6 EN SW RCL R6 1µF CSL C C 100kΩ FREQ 1.8kΩ OUT2 OUT1 R3 DL M2 1000µF 47µF 7.5kΩ SYNC ×2 ×2 X5R PGND 6.3V R1 C1 PGOOD 20kΩ 680pF FB COMP CLKOUT R2 R8 10kΩ SS CLKSET 20kΩ AGND PGND C2 C 33pF SS 200nF GND C3 5.6nF AGND f D1: BAT54 SW = 300kHz C M1: INFINEON, BSC080N03LS IN: SANYO, OSCON 20SP180M
001
C M2: INFINEON, 2 × BSC030N03LS OUT2: SANYO, POSCAP 2R5TPD1000M5 L1: WURTH ELEKTRONIC, 0.82µH, 744355182
06865- Figure 1. Typical Application Circuit with 20 A Output
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION SIMPLIFIED BLOCK DIAGRAM PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION INPUT POWER INTERNAL LINEAR REGULATOR SOFT START ERROR AMPLIFIER CURRENT-LIMIT SCHEME MOSFET DRIVERS SETTING THE OUTPUT VOLTAGE SWITCHING FREQUENCY CONTROL AND SYNCHRONIZATION COMPENSATION POWER-GOOD INDICATOR THERMAL SHUTDOWN SHUTDOWN CONTROL TRACKING APPLICATION INFORMATION SELECTING THE INPUT CAPACITOR OUTPUT LC FILTER SELECTING THE MOSFETS SETTING THE CURRENT LIMIT ACCURATE CURRENT-LIMIT SENSING FEEDBACK VOLTAGE DIVIDER COMPENSATING THE VOLTAGE MODE BUCK REGULATOR Type II Compensator Type III Compensator SOFT START SWITCHING NOISE AND OVERSHOOT REDUCTION VOLTAGE TRACKING COINCIDENT TRACKING RATIOMETRIC TRACKING THERMAL CONSIDERATIONS PCB LAYOUT GUIDELINE RECOMMENDED COMPONENT MANUFACTURERS APPLICATION CIRCUITS OUTLINE DIMENSIONS ORDERING GUIDE