ADP1109A

a FEATURES Operates at Supply Voltages 2 V to 9 V Fixed 3.3 V, 5 V, 12 V and Adjustable Output Minimum External Components Required Ground Current: 460 ␮ A Oscillator Frequency: 120 kHz Logic Shutdown 8-Lead DIP and SO-8 Packages APPLICATIONS Cellular Telephones Single-Cell to 5 V Converters Laptop and Palmtop Computers Pagers Cameras Battery Backup Supplies Portable Instruments Laser Diode Drivers Hand-Held Inventory Computers Micropower Low Cost Fixed 3.3 V, 5 V, 12 V and Adjustable DC-to-DC Converter ADP1109A FUNCTIONAL BLOCK DIAGRAM VIN SENSE R2 250k⍀ COMPARATOR 1.25V REFERENCE A1 120kHz OSCILLATOR DRIVER Q1 ADP1109A-3.3: R1 = 152k⍀ ADP1109A-5: R1 = 83k⍀ ADP1109A-12: R1 = 29k⍀ SW R1 GND SHUTDOWN PGND VIN FB ADP1109A COMPARATOR SW 120kHz OSCILLATOR DRIVER GENERAL DESCRIPTION 1.25V REFERENCE A1 Q1 The ADP1109A is a versatile step-up switching regulator. The device requires only minimal external components to operate as a complete switching regulator. The ADP1109A-5 can deliver 100 mA at 5 V from a 3 V input and the ADP1109A-12 can deliver 60 mA at 12 V from a 5 V input. The device also features a logic controlled shutdown capability that, when a logic low is applied, will shut down the oscillator. The 120 kHz operating frequency allows for the use of small surface mount components. The gated oscillator capability eliminates the need for frequency compensation. GND SHUTDOWN PGND TYPICAL APPLICATION L1 33␮H D1 3 VIN 5V 1 VIN SW SENSE 8 ADP1109A-12 7 ...