Advanced Monolithic Systems AMS4154 2A OUTPUT PWM BUCK CONVERTER RoHS compliant FEATURES APPLICATIONS • Stable with low ESR Output Ceramic Capacitors • Up to 99% On time • 2A Output Current • Wide Operating Input Voltage Range 5.5V to 32V • Fixed 330 kHz Frequency • Thermal Shutdown • Cycle-by-cycle Over Current Protection • Under Voltage Lockout • 5V reference output • Adjustable output from 0.6V • Battery Chargers • Portable (Notebook) Computers • Industrial power supply • Point of regulation for high performance electronics • Consumer Electronics • Audio Power Amplifiers • Distributed Power Systems • Pre-Regulator for Linear Regulators • LCD TVs and LCD monitors • Automotive electronics GENERAL DESCRIPTION The AMS4154 is a step-down converter for high voltage applications. Current mode operation provides easier compensation and fast transient response. Internal cycle-by-cycle current limiting and thermal shutdown provides the necessary protection in faults situation. A 5V reference voltage is available that can supply up to 2mA current. ORDERING INFORMATION OUTPUT PACKAGE TYPE VOLTAGE TEMP. RANGE 8 Lead SOIC Adjustable AMS4154S -25°C to 125°C PIN CONNECTIONS TYPICAL APPLICATION 8L SOIC SO Package (S) VIN BST 470n ON OFF 2.5V/2A L1 EN LX 4.7µH 31.7K COMP 10µF VREF 1 8 REF VIN 2 7 EN LX 3 6 COMP GND 4 5 F/B 22µF 3.9K GND BST F/B 10K Top View B220 4.7n Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4154 PIN DESCRIPTION AMS4154 PIN NUMBERS NAME DESCRIPTION 1 BST Bootstrap. A capacitor is needed to drive the power switch’s drive above the supply voltage. It is connected between LX and BST pins to form a floating supply across the power switch driver. 2 VIN Supply Voltage. The AMS4154 operates from a+5.5V to +32V unregulated input. C1 is needed to prevent large voltage spikes from appearing at the input. 3 LX Switch. This connects the inductor to VIN through the internal power switch. 4 GND Ground. This pin is the ground for voltage reference and for the regulated output voltage. For this reason care must be taken in its layout. 5 FB Feedback. An external resistor divider from the output to GND, tapped to the FB pin sets the output voltage. 6 COMP Compensation. This node is the output of the transconductance error amplifier and the input to the current comparator. Frequency compensation is done at this node by connecting a series R-C to ground. 7 EN Enable. A voltage greater than 2.5V enables operation. For complete low current shutdown the EN pin voltage needs to be less than 2.3V. 8 REF 5V reference voltage capable of supplying 1mA for other external circuits. Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4154 ABSOLUTE MAXIMUM RATINGS Input Supply Voltage SW Voltage BS Voltage All Other Pins -0.3V to +34V -1V to VIN + 0.3V V LX – 0.3V to V LX + 6V -0.3V to +6V Junction Temperature Storage Temperature Lead Temperature +150°C -65°C to +150°C 260°C ELECTRICAL CHARACTERISTICS Electrical Characteristics at TA= 25 °C and VIN=12V (unless otherwise noted). PARAMETER TEST CONDITIONS Min. AMS4154 Typ. Max. 0.588 0.600 0.612 V Units Feedback Voltage 0.6V ≤ VIN ≤ 32V, VCOMP < 2V Supply Current VEN = 5V, VFB = 1.4V 1.0 1.2 mA Shutdown Supply Current VEN = 0V 0.5 1 µA 3.6 4.9 A Current Limit 2.5 Current Sense to COMP Transconductance Oscillation Frequency Maximum Duty Cycle Minimum Duty Cycle EN Threshold Voltage EN Threshold Voltage EN Threshold Hysteresis Enable Current Thermal Shutdown 5V REF Voltage REF Load Regulation REF Line Regulation 3.5 280 VFB = 1.0V VFB = 1.5V VEN Rising, Output ON VEN Falling , Output OFF 2.5 VEN = 0V IREF = 0 ∆IREF = 0 to 1mA IREF = 100µA, VIN = 6.5 to 32V Advanced Monolithic Systems, Inc. www.advanced-monolithic.com 4.8 330 90 0 2.6 2.2 250 1.8 160 5.0 100 30 Phone (925) 443-0722 A/V 380 99 2.8 2.3 5.2 KHz % % V V mV µA ºC V mV mV Fax (925) 443-0723 AMS4154 TYPICAL WAVEFORM Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4154 PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted. 8 LEAD SOIC PLASTIC PACKAGE (S) 0.189-0.197* (4.801-5.004) 8 7 6 8 5 0.228-0.244 (5.791-6.197) 0.123 (3.12) 0.137 (3.48) 7 6 5 0. 150-0.157** (3.810-3.988) 1 2 3 1 4 2 3 4 0.010-0.020 x 45° (0.254-0.508) 0.053-0.069 (1.346-1.752) 0.004-0.010 (0.101-0.254) 0.014-0.019 (0.355-0.483) 0.024(0.61) 0.090 (2.28) 0.102 (2.59) 0.008-0. 010 (0.203-0.254) 0.050 (1.270) TYP 0°-8 ° TYP 0.016-0.050 (0.406-1.270) S (SO- 8 ) AMS DRW# 042293 *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 0.050(1.27) 0.063(1.60) **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 0.105(2.67) 0.213(5.41) 0.138 (3.50) RECOMMENDED LAYOUT PATTERN Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723