AMS4122

Advanced Monolithic Systems FEATURES AMS4122 SINGLE 4A/DUAL 2A BUCK CONVERTER IN SO8 RoHS compliant APPLICATIONS • Audio Power Amplifiers • Portable (Notebook) Computers • Point of regulation for high performance electronics • Consumer Electronics • Desktop Computers • LCD TVs and LCD monitors • Distributed Power Systems • Battery Chargers • Pre-Regulator for Linear Regulators • 2 Independent Asynchronous Buck Converters in SO-8 • Internally compensated • Built in soft start • Enable with Zero current shut down • 400KHz switching per output • Interleaved oscillator to reduced supply ripple • Simply re-configures to 2 phase single output • Up to 4A output in 2 phase mode • Independent hiccup current limit GENERAL DESCRIPTION AMS4122 is a dual switching regulator capable to deliver up to 2A for each channel. Internally Compensated internal Soft Start makes AMS4122 one of the simplest and easiest switching regulators to use with the minimum external components. Each regulator has independent hiccup current limit. The Enable pin turns both devices on when a voltage of 2.5V or higher it is applied to EN pin. Since both devices share one single package the thermal protection turns off both devices when the die temperature exceeds approximately 135°C. Both regulators are adjustable using a 0.600V reference for low output voltage settings. The oscillators are 180° phase to each other to reduce the ripples on the input power supply and minimize the power dissipation on the package. The device can be easily configured for Two Phase single output switching regulator capable of 5A output load. By applying a 2.5V or greater on feedback pin of the second switching regulator the device enters in Two Phase Mode. The first benefit of having a Two Phase device is reducing the output ripples by a factor of four as the single phase. The second benefit is higher output current capability at overall low cost. AMS4122 combined with AMS4123 (2A Switching Regulator + 1A LDO in SO-8) makes complete solution for LCD TV power requirements. ORDERING INFORMATION Package Type SOIC EDP AMS4122S TEMP. RANGE PINCONNECTIONS -25°C to 125°C TYPICAL APPLICATION 8L SOIC SO Package (S) SW 2 P2VIN GND F/ B 2 1 2 3 4 8 7 6 5 SW 1 P1+AVIN EN F/ B 1 Top View Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4122 PIN DESCRIPTION Pin Number 1 2 3 4 NAME SW2 P2VIN GND F/B2 DESCRIPTION This connects the inductor the Internal Switch2 Input Power Pin for SW2 from unregulated power supply Ground Pin connected to PCB ground plane. This pin is also the ground for internal voltage reference. Feedback2. A resistor network of two resistors is used to set-up the output voltage connected between Output2 to GND. The node between the two resistors is connected to Feedback2 pin. In Two Phase Mode F/B2 should be connected to a voltage 2.5V or higher Feedback1. A resistor network of two resistors is used to set-up the output voltage connected between Output1 to GND. The node between the two resistors is connected to Feedback1 pin. Enable. A voltage greater than 2.5V at this pin enables both devices operation. Input Power Pin for SW1 and Analog Input Voltage that powers up the chip This connects the inductor the Internal Switch1 5 F/B1 6 7 8 EN P1+AVIN SW1 RECOMMANDED OPERATING CONDITIONS: The minimum input voltage should be 4.5V, however the device will function as low as 4.0V. The maximum operating voltage should be 20V, the device will work at 22V but the switching loss is higher. The best performance is at 1.5A output load per channel; however it works well with 2A load per channel. The minimum supply voltage is Vout +1Vfor 1A load and Vout +1.1V for 2A load but must be higher than 4.2V. There is an internal UVLO that will turn off the device if the input voltage is below 4.0V. When the input voltage exceeds 12V the output load current should be maintain below 1.5A, due to switching loss the device will have lower performance. Advanced Monolithic Systems, Inc. www.advanced-monolithic.com Phone (925) 443-0722 Fax (925) 443-0723 AMS4122 ABSOLUTE MAXIMUM RATINGS VIN F/B EN 4.0V to 20V -0.3 to +12.0V -0.3V to +20V Junction Temperature Storage Temperature Lead temperature +150ºC -65ºC to +150ºC 260ºC ELECTRICAL CHARACTERISTICS Electrical Characteristics at TA= 25 °C and VIN=12V (unless otherwise noted). PARAMETER Feedback voltage Full Load Output Current Feedback2 (note 1) Phase Shift between Outputs Current Limit Phase current match Oscillator Frequency Maximum 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 Total Power dissipation Note (3) 2.5 120 0.7 3.5 150 100 1.5 135 2.5 1.9 TEST CONDITIONS F/B-1 and F/B-2 Measured on each channel (note 4) Two Phase Mode Dual Output Mode Per Output Dual Phase Single Output Mode Note(2) 360 171 Min. 0.590 AMS4122 Typ. 0.6 1.3 180 4 10 400 440 100 Max. 0.610 2 2.5 189 Units V A V