AMS1069 FEATURES DESCRIPTION 2A Output Current Wide 4.75V to 18V Operating Input Range Integrated Power MOSFET Switches Output Adjustable from 0.905V to 15V Up to 93% Efficiency Programmable Soft-Start Stable with Low ESR Ceramic Output Capacitors Fixed 380KHz Frequency Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout The AMS1069 is a monolithic synchronous buck regulator. The device integrates two MOSFETs, and provides 2A of continuous load current over a wide input voltage of 4.75V to 18V. 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 to 1µA. APPLICATIONS This device, available in an SOP8/ESOP8 package, provides a very compact solution with minimal external components. Distributed Power Systems Networking Systems FPGA, DSP, ASIC Power Supplies Green Electronics/ Appliances Notebook Computers TYPICAL APPLICATION C5 10nF INPUT 2 7 1 IN BS 3 SW EN 3.3V 2A AMS1069 8 SS GND FB COMP 4 5 6 C3 3.3nF VOUT = 0.905 × R1 + R2 R2 R2 can be as high as 100kΩ, but a typical value is 10kΩ. 1 Advanced Monolithic Systems http://www.ams-semitech.com AMS1069 ABSOLUTE MAXIMUM RATINGS (1) PACKAGE REFERENCE Supply Voltage VIN ....................... –0.3V to +20V Switch Node Voltage VSW ............................ 21V 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 TOP VIEW BS 1 8 SS IN 2 7 EN SW 3 6 COMP GND 4 5 FB Part Number* AMS1069 Recommended Operating Conditions (2) Input Voltage VIN ............................ 4.75V to 18V Output Voltage VOUT .................... 0.905V to 15V Ambient Operating Temperature .... –40°C to +85°C Package Temperature SOP8 –40° to +85°C Notes: 1) Exceeding these ratings may damage the device. 2) The device is not guaranteed to function outside of its operating conditions. ELECTRICAL CHARACTERISTICS VIN = 12V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition Shutdown Supply Current Supply Current Min VEN = 0V VEN = 2.0V; VFB = 1.0V Feedback Voltage VFB Feedback Overvoltage Threshold Error Amplifier Voltage Gain (4) Error Amplifier Transconductance High-Side Switch On Resistance (4) Low-Side Switch On Resistance (4) High-Side Switch Leakage Current Upper Switch Current Limit Lower Switch Current Limit COMP to Current Sense Transconductance Oscillation Frequency Short Circuit Oscillation Frequency Maximum Duty Cycle Minimum On Time (4) EN Shutdown Threshold Voltage EN Shutdown Threshold Voltage Hysteresis EN Lockout Threshold Voltage EN Lockout Hysterisis 4.75V ≤ VIN ≤ 18V 0.885 ∆IC = ±10µA Units 1 1.3 3.0 1.5 µA mA 0.905 0.925 V V V/V 700 µA/V - RDS(ON)1 RDS(ON)2 VEN = 0V, VSW = 0V Minimum Duty Cycle From Drain to Source VFB = 0V VFB = 1.0V VEN Rising 1.1 3.5 A/V 380 100 90 220 1.5 KHz KHz % ns V 2.0 210 2.2 2 Advanced Monolithic Systems 3.2 1.0 mΩ mΩ µA A A 10 GCS Fosc1 Fosc2 DMAX Max 1.1 400 AEA GEA Typ http://www.ams-semitech.com 2.5 210 mV 2.7 V mV AMS1069 ELECTRICAL CHARACTERISTICS (continued) VIN = 12V, TA = +25°C, unless otherwise noted. Parameter Input Under Voltage Lockout Threshold Input Under Voltage Lockout Threshold Hysteresis Soft-Start Current Soft-Start Period Thermal Shutdown Symbol Condition Min VIN Rising VSS = 0V CSS = 0.1µF Typ Max Units 4.30 V 210 mV 6 15 160 µA ms °C 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 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 0.905V. 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. 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, drive it low to turn it off. Pull up with 100kΩ 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. 3 Advanced Monolithic Systems http://www.ams-semitech.com AMS1069 Functional Block Diagram + OVP 1.1V AMPLIFIER -OSCILLATOR + FB 5 100/380KHz RAMP + 2 IN 1 BS 3 SW 4 GND 5V -- CLK ---+ + SS 8 0.905V + ERROR AMPLIFIER S Q R Q COMPARATOR COMP 6 2.5V 1.2V + EN OK -- EN OVP LOCKOUT COMPARATOR IN + EN 7 INTERNAL REGULATORS 1.5V -- SHUTDOWN COMPARATOR 4 Advanced Monolithic Systems http://www.ams-semitech.com 5V AMS1069 PACKAGE INFORMATION SOP8 5 Advanced Monolithic Systems http://www.ams-semitech.com