DUAL 150MA HIGH PERFORMANCE MOBILE LDO

2007-7-4

3/9

FSP2151

FUNCTIONAL BLOCK DIAGRAM

TYPICAL APPLICATION CIRCUIT

APPLICATION INFORMATION

Capacitor Selection and Regulator Stability

Similar to any low dropout regulator, the external capacitors used with the FSP2151 must be carefully selected for

regulator stability and performance.

exceed 0.5 inch. Ceramic capacitors are suitable for the FSP2151. Capacitors with larger values and lower ESR

provide better PSRR and line-transient response.

The FSP2151 is designed specifically to work with low ESR ceramic output capacitors in order to save space and

improve performance. Using an output ceramic capacitor whose value is ＞2.2μF with ESR＞5mΩ ensure stability.

Shutdown Input Operation

The FSP2151 is shutdown by pulling the EN input low, and is turned on by tying the EN input to VIN or leaving the

EN input floating.

Dropout Voltage

A regulator’s minimum dropout voltage determines the lowest usable supply voltage. The FSP2151 has a typical

180mV dropout voltage. In battery powered systems, this will determine the useful end-of-life battery voltage.

Current Limit and Short Circuit Protection

The FSP2151 features a current limit, which monitors and controls the gate voltage of the pass transistor. The output

current can be limited to 300mA by regulating the gate voltage. The FSP2151 also has a built-in short circuit current

limit.