IRUH50P253A1M Datasheet, PDF (5/7 Pages) International Rectifier – Ultra Low Dropout Positive Fixed Linear Regulator +5.0Vin to +2.5Vout at 3.0A

IRUH50P253A1M
Vin
100uF 16V
Tantalum
Vin
Vout
IRUH50P253A1M
SHDN
GND
Vout
1.0uFx10
Ceramic X 7R
1000uF 6.3V
Low ESR Tantalum
Ground
Fig 2. Typical Application Circuit
Input Capacitance
Recommended input capacitance for a generic application is a 100µF, 16V tantalum capacitor. However, the
input capacitance is not critical to the stability of the regulator and is therefore application dependant. In
designs with a clean bus voltage that is situated close to the input of the regulator, only a small ceramic
capacitor will be needed to decouple high frequency noise. On the other hand , in designs with a noisy bus,
a larger capacitor will be needed. Care should be taken to ensure that the input to the regulator is sufficiently
free of noise and disturbances.
Output Capacitance
Like most ultra low dropout voltage regulators, IRUH50P253A1M requires the use of output capacitors as
part of the device frequency compensation. The device requires a minimum of 220µF tantalum to ensure
stability.
Many different types of capacitor are available and have widely varying characteristics. These capacitors
differ in capacitor tolerance, equivalent series resistance (ESR), equivalent series inductance and capacitance
temperature coefficient. The IRUH50P253A1M frequency compensation optimizes frequency response with
low ESR capacitors. In general, use capacitors with an ESR of less than 50mΩ for heavy load applications.
High quality bypass capacitors must be also be used to limit the high frequency noise generated by the load.
Multiple small ceramic capacitors are typically required to limit parasitic inductance (ESL) and ESR in the
capacitors to acceptable levels.
The upper limit of the capacitance is governed by the delayed over-current latch function of the regulator. The
regulator has a protection circuit that will latch the device off in the event of a short circuit. However, since it is
known that the regulator will draw a large in-rush current upon startup, the latch-off is delayed by about 10ms
to allow the outout capacitors to charge to a steady state without shutting down. During this period, the
regulator will have an output current at its maximum of around 5A typical. Therefore, the maximum output
capacitance can be as high as 20,000µF without causing device to latch-off during start-up.
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