A6303A
AiT Semiconductor Inc.
www.ait-ic.com
CMOS LOW DROPOUT REGULATOR (LDO)
300mA ULTRA-LOW NOISE, ULTRA-FAST RESPONSE
DETAILED INFORMATION
Like any low-dropout regulator, the external capacitors used with the A6303A must be carefully selected for
regulator stability and performance. Using a capacitor whose value is > 1μF on the A6303A input and the
amount of capacitance can be increased without limit. The input capactitor must be located a distance of not
more than 0.5 inch 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 capactitor. The capacitor with larger value and lower ESR
(equivalent series resistance) provides better PSRR and line-transient response. The output capacitor must
meet both requirements for minimum amount of capacitance and ESR in all LDOs application. The A6303A is
designed specifically to work with low ESR ceramic output capacitor in space-saving and performance
consideration. Using a ceramic capacitor whose vale is at least 1μF with ESR is > 25mΩ on the output
ensures stability. The A6303A still works well with output capacitor of other types due to the wide stable ESR
range. Output capacitor of larger capacitance can reduce noise and improve load transient response, stability,
and PSRR. The output capacitor should be located not more than 0.5 inch from the VOUT pin of the A6303A
and returned to a clean analog ground.
Enable Function (SOT-25, SC70-5)
The A6303A features an LDO regulator enable/disable function. To assure the LDO regulator will switch on;
the CE turn on control level must be greater than 1.2 volts. The LDO regulator will go into the shutdown mode
when the below 0.4 volts. For to protect the system, the A6303A have a quick discharge function. If the chip
enable function is not needed in a specific application, it may be tied to VIN to keep the LDO regulator in a
continuously on stste.
Thermal Considerations
Thermal protection limits power dissipation in A6303A. When the operation junction temperature exceeds 165
℃, the OTP circuit starts the themal shutdown function turn the pass element off. The pass element turns on
again after the junction temperature cools by 30℃.
For continue operation, do not exceed absolute maximum operation junction temperature 125℃. The power
dissipation definition in device is:
The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between junction to ambient. The maximum
power dissipation can be calculated by following formula：
REV1.4
-DEC 2009 RELEASED, NOV 2011 UPDATED -
- 9 -
AITSEMI [ AiT Semiconductor ]
