A6300
AiT Semiconductor Inc.
www.ait-ic.com
LOW DROPOUT VOLTAGE REGULATOR
300mA CMOS WITH ENABLE PIN
DETAILED INFORMATION
Capacitor Selection and Regulator Stability
As low-dropout regulator, the external capacitors used with the A6300 must be carefully selected for regulator
stability and performance.
Choose a capacitor which value is > 1μF on the A6300 input and the amount of capacitance can be increased
without limit. The input capacitor must be located a distance of not more than 0.5” from the input pin of the IC
and returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor.
The capacitor with larger values and lower ESR (equivalent series resistance) provides better PSRR and
line-transient response.
The output capacitor must meet with both requirements for minimum amount of capacitance and ESR in all
LDOs application. The A6300 is designed specifically to work with low ESR ceramic output capacitor in
space-saving and performance consideration. Using a ceramic capacitor which value is at least 2.2μF with
ESR is >5mΩ on the A6300 output ensures stability. The A6300 still work well with output capacitor of other
types due to the wide stable ESR range.
Note at some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It may be
necessary to use 2.2μF or more to ensure stability at temperature below -10℃ in this case. Also, tantalum
capacitors, 2.2μF or more may be needed to maintain capacitance and ESR in the stable region for strict
application environment.
Tantalum capacitors maybe suffer failure due to surge current when it is connected to a low-impedance
source of power (like a battery or very large capacitor). If a tantalum capacitor is used at the input, it must be
guaranteed to have a surge current rating sufficient for the application by the manufacture.
Use 10nF bypass capacitor at BP pin for low output voltage noise. The capacitor, in conjunction with an
internal 200KΩ resistor, which connects bypass pin and the band-gap reference, creates an 80Hz low-pass
filter for noise reduction. Increasing the capacitance will slightly decrease the output noise, but increase the
start-up time. The capacitor connected to the bypass pin for noise reduction must have very low leakage.
Mentioned capacitor leakage current will cause the output voltage to decline by a proportional amount to the
current due to the voltage drop on the internal 200KΩ resistor. See Fig.1 for the power on response.
REV1.4
- JUN 2006 RELEASED, FEB 2015 UPDATED -
13
AITSEMI [ AiT Semiconductor ]
