Advanced Monolithic Systems AMS4155 2A OUTPUT PWM BUCK CONVERTER RoHS compliant FEATURES APPLICATIONS • Stable with low ESR Output Ceramic Capacitors • Up to 95% Efficiency • 2A Continuous Output Current • Wide 4.75V to 20V Operating Input Range • Fixed 480kHz Frequency • Thermal Shutdown • Cycle-by-cycle + hiccup Over Current Protection • Under Voltage Lockout • Frequency Synchronization Input • Operating Temperature: -40°C to 125°C • Available in an 8-Pin SO Package • 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 GENERAL DESCRIPTION The AMS4155 is a monolithic step down switch mode converter with a built in internal power Switch Transistor. It achieves 2A continuous output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycleby-cycle current limiting and thermal shutdown. In shutdown mode the regulator draws 17µA of supply current. ORDERING INFORMATION OUTPUT PACKAGE TYPE VOLTAGE Adjustable TEMP. RANGE 8 Lead SOIC AMS4155S -25°C to 125°C PIN CONNECTIONS TYPICAL APPLICATION 8L SOIC INPUT 1µF 470µF/ 10µF CER ON OFF VIN EN 10 µH 2 8 4 OUTPUT 5V/3A LX AMS4155 SYNC SO Package (S) BST 3 B230A 6 F/B 1 5 GND SYNC 1 8 EN BST 2 7 COMP VIN 3 6 FB 5 GND 7 COMP 30kΩ 10nF 5kΩ 40µF ceramic LX 4 10kΩ Top View Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4155 PIN DESCRIPTION Pin Number NAME DESCRIPTION 1 SYNC Synchronization Input. This pin is used to synchronize the internal oscillator frequency to an external source. Leave SYNC unconnected or connect to GND if unused. 2 BST Bootstrap. This capacitor is needed to drive the power switch above the supply voltage. It is connected between LX and BST pins to form a floating supply across the power switch driver. The voltage across Cbst is about 5V and is supplied by the internal Vcc supply when LX pin voltage is low. 3 VIN Supply Voltage. The AMS4155 operates from a+4.75V to +23V unregulated input. Cin is needed to prevent large voltage spikes from appearing at the input power supply. 4 LX This connects the inductor to the internal Switch 5 GND Ground Pin connected to PCB ground plane. This pin is also the ground for internal voltage reference. 6 FB Feedback. A resistor network of two resistors is used to set-up the output voltage connected between Output to GND. The node between the two resistors is connected to Feedback pin. 7 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. 8 ENABLE Enable. A voltage greater than 2.495V at this pin enables device operation. Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4155 ABSOLUTE MAXIMUM RATINGS VIN F/B EN BST 28V -0.3V to +6V -0.3V to +6V VLX + 6V LX COMP SYNC -1V to +28V -0.3V to +6V -0.3v to +6V Junction Temperature Storage Temperature Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds +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 Feedback Voltage 4.75V ≤ VIN ≤ 20V, VCOMP < 2V Switch On Resistance Switch Leakage VEN = 0V; VLX = 0V Current Limit Min. 1.215 3.4 (1) Current Amplifier Gain Error Amplifier Voltage Gain Error Amplifier Transconductance Oscillator Frequency Sync Frequency Maximum Duty Cycle Minimum Duty Cycle Enable Threshold Enable Hysteresis Enable Pull-up Current Under Voltage Lockout Threshold Rising Under Voltage Lockout Threshold Hysteresis Supply Current (Shutdown) Supply Current (Quiescent) Thermal Shutdown ∆IC = ± 10µA Sync Drive 0.5V to 2.7V VFB = 1.0V VFB = 1.5V VEN ≤ 0.4V VEN ≥ 2.8V; VFB = 1.5V 420 0.460 AMS4155 Typ. 1.255 Max. Units 1.285 V 0.18 0 10 Ω µA 4 6 A 1.9 A/V 400 730 460 V/V µA/V KHz MHz % % V mV µA 500 1.1 85 3.2 2.55 2.2 2.475 220 0.7 2.4 2.5 2.6 V 200 17 0.95 153 25 1.1 mV µA mA °C Note: 1) Equivalent output current = 1.5A ≥ 50% Duty Cycle 2.0A ≤ 50% Duty Cycle Assumes ripple current = 30% of load current. Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4155 TYPICAL PERFORMANCE CHARACTERISTICS Light load start up Full load start up PWM rising edge PWM Falling edge Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4155 TYPICAL PERFORMANCE CHARACTERISTICS (continued) 0.5-3A transient on 5V output Full load Sat (reference = supply at IC) Typical waveform set at 3.3V output, 2A load and 12V input. Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4155 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