AMS1067 General Description Features The AMS1067 is a monolithic step down switch mode regulator with a built in internal Power MOSFET. 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 cycle-bycycle current limiting and thermal shutdown. In shutdown mode the regulator draws 25µA of supply current. The AMS1067 requires a minimum number of readily available standard external components. AMS1067 SOP8 / ESOP8 Applications PC Monitors Distributed Power Systems Battery Charger Pre-Regulator for Linear Regulators Ordering Information Part Number * Package 2A Output Current 0.22Ω Internal Power MOSFET Switch Stable with Low ESR Output Ceramic capacitors Up to 95% Efficiency 20µA Shutdown Mode Fixed 420KHz frequency Thermal Shutdown Cycle-by-cycle over current protection Wide 4.75 to 18V operating input range Output Adjustable from 1.22 to 15V Programmable under voltage lockout Available in SOP8 / ESOP8 Temperature -20 to +85 °C Typical Application Circuit INPUT 4.75 to 15V ENABLE SHUTDOWN OUTPUT 2.5V/2A AMS1067 1 Advanced Monolithic Systems http://www.ams-semitech.com AMS1067 Absolute Maximum Ratings (Note 1) Input Voltage (VIN) Switch Voltage (VSW) Boot Strap Voltage (VBS) All Other Pins Junction Temperature Lead Temperature Storage Temperature -0.3V to 20V -1V to VIN +1V VSW-0.3V toVSW+6V -0.3 to 6V 150°C 260°C -55°C to 150°C Recommended Operating Conditions (Note 2) 4.75V to 18V -20°C to +85°C Input Voltage (VIN) Operating Temperature Electrical Characteristics (Unless otherwise specified refer to Circuit of Figure 1, VEN=5V, VIN=12V, TA=25 C) Parameters Condition Feedback Voltage Upper Switch On Resistance Lower Switch On Resistance Upper Switch Leakage Current Limit Oscillator Frequency Short Circuit Frequency Maximum Duty Cycle Minimum Duty Cycle Enable Threshold Under Voltage Lockout Threshold High Going Under Voltage Lockout Threshold Hysteresis Shutdown Supply current Operating Supply current Thermal Shutdown 4.75V ≤ VIN ≤ 15V Min VEN=0V; VSW=0V 10 2.4 VFB = 0V VFB = 1.0V VFB = 1.5V 0.7 2.0 VEN ≤ 0.4V VEN=2.6V; VFB =1.4V Pin Description BS 1 8 N/C IN 2 7 EN SW 3 6 COMP GND 4 5 FB Max 1.22 0.22 10 Note 1. Exceeding these ratings may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. 2 Advanced Monolithic Systems Typ http://www.ams-semitech.com 2.80 420 42 90 0 1.0 2.5 200 25 1.0 160 1.3 3.0 50 1.5 Units V Ω Ω µA A KHz KHz % % V V mV µA mA °C AMS1067 Table 1: Pin Designator # Name 1 BS 2 IN 3 SW 4 5 GND FB 6 COMP 7 EN 8 N/C Description High-Side Gate Drive Boost Input. BS supplies the drive for the high-side n-channel MOSFET switch. Connect a 10nF or greater capacitor from SW to BS to power the high-side switch. Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.75V to 18V power source. Bypass IN to GND with a suitably large capacitor to eliminate noise on the input to the IC. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BS to power the high-side switch. Ground. Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive voltage divider from the output voltage. The feedback threshold is 1.22V. Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation control loop. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator, drive it low to turn it off. For automatic startup, leave EN unconnected. No Connect Functional Block Diagram 3 Advanced Monolithic Systems http://www.ams-semitech.com AMS1067 AMS1067 Step Down from 4.75V-18V to 2.5V @ 2A VOUT=1.22((R1+R2)/R2) Schottky Diode Manufacturers Schottky Rectifier Selection Guide VIN (Max) 15V 20V # 1 2 3 4 5 6 2A Current Load Part Number 30BQ15 B220 SK23 SR32 Vendor 4 1 6 6 2.5V 3.3V 5V 12V 2.5V 3.3V 5V 12V C2 22µF Ceramic 22µF Ceramic 22µF Ceramic 22µF Ceramic 560µF/6.3V (30mΩ ESR) 560µF/6.3V (30mΩ ESR) 470µF/10V (30mΩ ESR) 220µF/25V (30mΩ ESR) R3 Web Site www.diodes.com www.fairchildsemi.com www.gensemi.com www.irf.com www.onsemi.com www.panjit.com.tw Inductor Selection Guide Compensation Values for Typical Output Voltage /Capacitor Combinations Vout Vendor Diodes, Inc. Fairchild Semiconductor General Semiconductor International Rectifier On Semiconductor Pan Jit International Vendor/Model C3 C6 7.5KΩ 10KΩ 15KΩ 33KΩ 2.2nF 2.0nF 1.2nF 1.0nF None None None None 200KΩ 1.0nF 100pF 200KΩ 18nF 82pF 250KΩ 1.0nF 56pF 250KΩ 1.0nF 27pF Core Material Package Dimensions (mm) W L H Open Open Shielded Shielded Shielded Shielded Ferrite Ferrite Ferrite Ferrite Ferrite Ferrite 7.0 7.3 5.5 5.5 6.7 10.1 7.8 8.0 5.7 5.7 6.7 10.0 5.5 5.2 5.5 5.5 3.0 3.0 Shielded Shielded Shielded Open Ferrite Ferrite Ferrite Ferrite 5.0 7.6 10.0 9.7 5.0 7.6 10.0 11.5 3.0 5.1 4.3 4.0 Open Open Ferrite Ferrite 9.4 9.4 13.0 13.0 3.0 5.1 Core Type Sumida CR75 CDH74 CDRH5D28 CDRH5D28 CDRH6D28 CDRH104R Toko D53LC Type A D75C D104C D10FL Coilcraft DO3308 DO3316 4 Advanced Monolithic Systems http://www.ams-semitech.com AMS1067 Packaging ESOP8 NOTE: 1) Control dimension is in inches. Dimension in bracket is millimeters. 5 Advanced Monolithic Systems http://www.ams-semitech.com