A6318
REGULATOR CMOS LOW DROPOUT REGULATOR (LDO)
300mA ULTRA-LOW NOISE, ULTRA-FAST
AiT Semiconductor Inc.
www.ait-ic.com
APPLICATIONS INFORMATION
Like any low-dropout regulator, the external capacitors used with the A6318 must be carefully selected for
regulator stability and performance. Using a capacitor whose value is > 1μF on the A6318 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 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 capacitor. 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 A6318 is designed specifically to work with low ESR ceramic output capacitor in space-saving and
performance consideration. Using a ceramic capacitor whose value is at least 1μF with ESR is > 25mΩ on
the A6318 output ensures stability. The A6318 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 A6318 and returned to a clean analog ground.
Bypass Capacitor and Low Noise
Connecting a 22nF between the BP pin and GND pin significantly reduces noise on the regulator output, it is
critical that the capacitor connection between the BP pin and GND pin be direct and PCB traces should be as
short as possible. There is a relationship between the bypass capacitor value and the LDO regulator turn on
time. DC leakage on this pin can affect the LDO regulator output noise and voltage regulation performance.
Enable Function
The A6318 features an LDO regulator enable/ disable function. To assure the LDO regulator will switch on;
the EN turn on control level must be greater than 1.2 volts.
The LDO regulator will go into the shutdown mode when the voltage on the EN pin falls below 0.4 volts. For to
protect the system, the A6318 have a quick discharge function. If the enable function is not needed in a
specific application, it may be tied to VIN to keep the LDO regulator in a continuously on state.
REV2.1
- JAN 2010 RELEASED, FEB 2014 UPDATED -
- 8 -
AITSEMI [ AiT Semiconductor ]
