AMS1117-3.3

IC LDO REG 3.3V 1A SOT223

DESCRIPTION

The AMS1117 is a positive low voltage dropout regulator; typical voltage dropout is only 1.2V at 1A.

AMS1117 provides two versions: fixed and adjustable versions. VOUT has a tolerance of less than 1.5% for fixed versions 1.2V 1.5V, 1.8V, 2.5V, 3.3V, 5.0V and adjustable version or 2% output accuracy for fixed version 1.2V.

The AMS1117 offers some key features include thermal shutdown and current limiting. It is suitable for all electronic products.

FEATURES

w 1.5%output accuracy for fixed versions 1.2V,1.5V, 1.8V 2.5V, 3.3V, 5.0V and adjustable version

w Adjustable output voltage

w LowDropout Voltage: Typical 1.2V@1A

w Current Limiting

w ThermalShutdown

w Temperature Range:-40°C to 125°C

APPLICATIONS

w Laptop, Palmtop, and NotebookComputers

w Battery Charger

w SCSI-II ActiveTerminator

w Cellular Phone

w CordlessTelephones

w Battery Powered Systems

w Portable Instrumentation

w SMPSPost-Regulator

NOMENCLATURE

BLOCKDIAGRAM

FUNCTION DESCRIPTION

The AMS1117 is a LDO regulator, it’s pass transistor is made up of a single NPN transistor being driven by a PNP. The dropout voltage is defined as: VDROP = VBE+ VSAT.

The AMS1117 series of fixed and adjustable regulators are easy to use. Output voltages are 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, and 5.0V.On-chip thermal shut down provides protection against any combination of overload and ambient temperature that would create excessive junction temperature.

The AMS1117 requires an output capacitor for device stability. Its value of 22mF tantalum covers all cases of bypassing the adjustment terminal. Without bypassing the adjustment terminal smaller capacitors can be used with equally good results which depend upon the application circuit. In general, linear regulator stability decreases with higher output currents.