AMS1070 DESCRIPTION FEATURES The AMS1070 is a monolithic synchronous buck regulator. The device integrates 100mΩ MOSFETS that provide 3A of continuous load current over a wide operating input voltage of 4.75V to 23V. Current mode control provides fast transient response and cycle-by-cycle current limit. • • • • • • • • • • • An adjustable soft-start prevents inrush current at turn-on and in shutdown mode, the supply current drops below 1µA. This device, available in an 8-pin ESOP8 package, provides a very compact system solution with minimal reliance on external components. 3A Continuous Output Current 4A Peak Output Current Wide 4.75V to 23V Operating Input Range Integrated 100mΩ Power MOSFET Switches Output Adjustable from 0.925V to 20V Up to 95% Efficiency Programmable Soft-Start Stable with Low ESR Ceramic Output Capacitors Fixed 380KHz Frequency Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Thermally Enhanced 8-Pin ESOP8 Package APPLICATIONS • • • Distributed Power Systems Networking Systems Notebook Computers TYPICAL APPLICATION C5 10nF INPUT 4.75V to 23V R4 100K 7 C1 10uF/25V CERAMIC X 2 8 2 1 IN BS SW EN AMS1070 SS GND 4 C4 0.1uF FB COMP 3 5 6 C3 3.9nF R3 6.8K L1 10uH (4A) R1 26.1K R2 10K OUTPUT 3.3V 3A C2 22uF/6.3V CERAMIC X 2 1 Advanced Monolithic Systems http://www.ams-semitech.com AMS1070 ABSOLUTE MAXIMUM RATINGS (1) Supply Voltage VIN ....................... –0.3V to +26V Switch Voltage VSW ................. –1V to VIN + 0.3V Boost Voltage VBS ..........VSW – 0.3V to VSW + 6V All Other Pins................................. –0.3V to +6V Junction Temperature...............................150°C Lead Temperature ....................................260°C Storage Temperature .............–65°C to +150°C Recommended Operating Conditions (2) Input Voltage VIN ............................ 4.75V to 23V Output Voltage VOUT .................... 0.925V to 20V Ambient Operating Temp .............. –40°C to +85°C Notes: 1) 2) Exceeding these ratings may damage the device. The device is not guaranteed to function outside of its operating conditions. 1 ELECTRICAL CHARACTERISTICS VIN = 12V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units Shutdown Supply Current VEN = 0V 1.0 3.0 µA Supply Current VEN = 2.0V, VFB = 1.0V 1.3 1.5 mA 0.925 0.950 V Feedback Voltage VFB 4.75V ≤ VIN ≤ 23V 0.900 Feedback Overvoltage Threshold Error Amplifier Voltage Gain (3) 1.1 V 400 V/V 820 µA/V RDS(ON)1 100 mΩ RDS(ON)2 100 AEA Error Amplifier Transconductance High-Side Switch On-Resistance (3) Low-Side Switch On-Resistance (3) GEA ∆IC = ±10µA High-Side Switch Leakage Current VEN = 0V, VSW = 0V Upper Switch Current Limit Minimum Duty Cycle Lower Switch Current Limit From Drain to Source COMP to Current Sense Transconductance GCS Oscillation Frequency Fosc1 Short Circuit Oscillation Frequency Fosc2 VFB = 0V Maximum Duty Cycle DMAX VFB = 1.0V Minimum On Time (3) 0 4.0 TON EN Shutdown Threshold Voltage VEN Rising 1.1 EN Shutdown Threshold Voltage Hysterisis 2 µA 5.8 A 0.9 A 5.2 A/V 380 KHz 110 KHz 90 % 210 ns 1.5 220 Advanced Monolithic Systems http://www.ams-semitech.com mΩ 10 2.0 V mV AMS1070 ELECTRICAL CHARACTERISTICS (continued) VIN = 12V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition EN Lockout Threshold Voltage EN Lockout Hysterisis Input Under Voltage Lockout Threshold Input Under Voltage Lockout Threshold Hysteresis Soft-Start Current Soft-Start Period Thermal Shutdown (3) Min Typ Max Units 2.2 2.5 210 2.7 V mV VIN Rising VSS = 0V CSS = 0.1µF Note: 3) Guaranteed by design, not tested. 3 Advanced Monolithic Systems http://www.ams-semitech.com 4.3 V 210 mV 6 15 160 µA ms °C AMS1070 PIN FUNCTIONS Pin # Name 1 BS 2 IN 3 SW 4 GND 5 FB 6 COMP 7 EN 8 SS Description High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET switch. Connect a 0.01µF 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 23V 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 (Connect the exposed pad to Pin 4). Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive voltage divider connected to it from the output voltage. The feedback threshold is 0.925V. Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator; low to turn it off. Attach to IN with a 100kΩ pull up resistor for automatic startup. Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms. To disable the soft-start feature, leave SS unconnected. 4 Advanced Monolithic Systems http://www.ams-semitech.com AMS1070 Functional Block Diagram Current OPA Enable Referance Offset Error OPA OTP OVP LVP 5 Advanced Monolithic Systems http://www.ams-semitech.com AMS1070 TYPICAL APPLICATION CIRCUIT C5 10nF INPUT 4.75V to 23V R4 100K 7 C1 10uF/25V CERAMIC X 2 2 BS SW EN AMS1070 8 SS GND FB COMP 4 C4 0.1uF L1 10uH (4A) 1 IN 3 C3 3.9nF C6 (optional) R1 26.1K 5 6 OUTPUT 3.3V 3A D1 B130 (optional) R2 10K C2 22uF/6.3V CERAMIC X 2 R3 6.8K VOUT=0.925X(1+R1/R2) AMS1070 with 3.3V Output, 22uF/6.3V Ceramic Output Capacitor Recommended Resistance Values VOUT R1 1.8V 2.5V 3.3V 5V 12V 9.53K 16.9K 26.1K 44.2K 121K R2 10K 10K 10K 10K 10K 6 Advanced Monolithic Systems http://www.ams-semitech.com AMS1070 Packaging ESOP8 NOTE: 1) Control dimension is in inches. Dimension in bracket is millimeters. 7 Advanced Monolithic Systems http://www.ams-semitech.com