Datasheet ADP1882, ADP1883 (Analog Devices)

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Synchronous Current-Mode with Constant On-Time, PWM Buck Controller ADP1882/ADP1883 FEATURES TYPICAL APPLICATIONS CIRCUIT Power input voltage as low as 2.75 V to 20 V VIN = 2.75V TO 20V Bias supply voltage range: 2.75 V to 5.5 V Minimum output voltage: 0.8 V VIN CC ADP1882/ C 0.8 V reference voltage with ±1.0% accuracy CC2 IN RC ADP1883 R Supports all N-channel MOSFET power stages TOP COMP/EN BST VOUT CBST Q1 Available in 300 kHz, 600 kHz, and 1.0 MHz options L FB DRVH VOUT R No current-sense resistor required BOT GND SW COUT Power saving mode (PSM) for light loads (ADP1883 only) C Q2 VDD2 VDD DRVL Resistor-programmable current-sense gain PGND RRES LOAD Thermal overload protection V
1
DD = 2.75V TO 5.5V C
00
VDD
1-
Short-circuit protection
90 08
Precision enable input
Figure 1.
Integrated bootstrap diode for high-side drive 140 μA shutdown supply current 100 Starts into a precharged load 95 Small, 10-lead MSOP package 90 85 APPLICATIONS VDD = 5.5V, VIN = 13.0V 80 VDD = 5.5V, VIN = 16.5V 75 Telecom and networking systems ) % V 70 DD = 5.5V, VIN = 5.5V (PSM) V Mid to high end servers Y ( DD = 5.5V, VIN = 5.5V C 65 VDD = 3.6V, VIN = 5.5V Set-top boxes IEN 60 IC DSP core power supplies F 55 EF 50 TA = 25°C V 45 OUT = 1.8V fSW = 300kHz 40 WURTH INDUCTOR: 35 744325120, L = 1.2µH, DCR = 1.8mΩ 30 INFINEON MOSFETs: BSC042N03MS G (UPPER/LOWER) 25 100 1k 10k 100k
02 0 1-
LOAD CURRENT (mA)
90 08 Figure 2. ADP1882/ADP1883 Efficiency vs. Load Current (VOUT = 1.8 V, 300 kHz)
GENERAL DESCRIPTION
The ADP1882/ADP1883 are versatile current-mode, synchronous Available in three frequency options (300 kHz, 600 kHz, and step-down controllers that provide superior transient response, 1.0 MHz, plus the PSM option), the ADP1882/ADP1883 are optimal stability, and current-limit protection by using a constant well suited for a wide range of applications. These ICs not only on-time, pseudo-fixed frequency with a programmable current- operate from a 2.75 V to 5.5 V bias supply, but they also can limit, current-control scheme. In addition, these devices offer accept a power input as high as 20 V. optimum performance at low duty cycles by using valley current- In addition, an internally fixed soft start period is included to limit mode control architecture. This allows the ADP1882/ADP1883 input in-rush current from the input supply during startup and to drive all N-channel power stages to regulate output voltages to provide reverse current protection during soft start for a pre- as low as 0.8 V. charged output. The low-side current-sense, current-gain scheme The ADP1883 is the power saving mode (PSM) version of the and integration of a boost diode, along with the PSM/forced device and is capable of pulse skipping to maintain output pulse-width modulation (PWM) option, reduce the external regulation while achieving improved system efficiency at light part count and improve efficiency. loads (see the Power Saving Mode (PSM) Version (ADP1883) The ADP1882/ADP1883 operate over the −40°C to +125°C section for more information). junction temperature range and are available in a 10-lead MSOP.
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Document Outline FEATURES APPLICATIONS TYPICAL APPLICATIONS CIRCUIT GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE BOUNDARY CONDITION ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS ADP1882/ADP1883 BLOCK DIAGRAM THEORY OF OPERATION STARTUP SOFT START PRECISION ENABLE CIRCUITRY UNDERVOLTAGE LOCKOUT THERMAL SHUTDOWN PROGRAMMING RESISTOR (RES) DETECT CIRCUIT VALLEY CURRENT-LIMIT SETTING HICCUP MODE DURING SHORT CIRCUIT SYNCHRONOUS RECTIFIER POWER SAVING MODE (PSM) VERSION (ADP1883) TIMER OPERATION PSEUDO-FIXED FREQUENCY APPLICATIONS INFORMATION FEEDBACK RESISTOR DIVIDER INDUCTOR SELECTION OUTPUT RIPPLE VOLTAGE (ΔVRR) OUTPUT CAPACITOR SELECTION COMPENSATION NETWORK Output Filter Impedance (ZFILT) Error Amplifier Output Impedance (ZCOMP) Error Amplifier Gain (GM) Current-Sense Loop Gain (GCS) Crossover Frequency EFFICIENCY CONSIDERATIONS Channel Conduction Loss MOSFET Driver Loss Switching Loss Diode Conduction Loss Inductor Loss INPUT CAPACITOR SELECTION THERMAL CONSIDERATIONS DESIGN EXAMPLE Input Capacitor Inductor Current Limit Programming Output Capacitor Feedback Resistor Network Setup Compensation Network Loss Calculations EXTERNAL COMPONENT RECOMMENDATIONS LAYOUT CONSIDERATIONS IC SECTION (LEFT SIDE OF EVALUATION BOARD) POWER SECTION DIFFERENTIAL SENSING TYPICAL APPLICATIONS CIRCUITS DUAL-INPUT, 300 kHz HIGH CURRENT APPLICATIONS CIRCUIT SINGLE-INPUT, 600 kHz APPLICATIONS CIRCUIT DUAL-INPUT, 300 kHz HIGH CURRENT APPLICATIONS CIRCUIT OUTLINE DIMENSIONS ORDERING GUIDE