A6318
REGULATOR CMOS LOW DROPOUT REGULATOR (LDO)
300mA ULTRA-LOW NOISE, ULTRA-FAST
AiT Semiconductor Inc.
www.ait-ic.com
Programming the A6318 Adjustable LDO regulator
The output voltage of the A6318 adjustable regulator is programmed using an external resistor divider as
show in Figure as below. The output voltage is calculated using equation as below:
Where: VREF=1.23V typ. (the internal reference voltage) .Resistors R1 and R2 should be chosen for
approximately 50uA divider current. Lower value resistors can be used for improved noise performance, but
the solution consumes more power. Higher resistor values should be avoided as leakage current into/out of
FB across R1/R2 creates an offset voltage that artificially increases/decreases the feedback voltage and thus
erroneously decrease/increases VOUT. The recommended design procedure is to choose R2=30.1KΩ to set
the divider current at 50uA, C1=22pF for stability, and then calculate using Equation as below:
In order to improve the stability of the adjustable version, it is suggested that a small compensation capacitor
be placed between OUT and FB. The suggested value of this capacitor for several resistor ratios is shown in
the table below.
OUTPUT VOLTAGE PROGRAMMING GUIDE
OUTPUT VOLTAGTE
R1
R2
C1
1.8V
2.5V
3.3V
3.6V
13.9 KΩ
31.6 KΩ
51 KΩ
59 KΩ
30.1 KΩ
30.1 KΩ
30.1 KΩ
30.1 KΩ
22pF
22pF
22pF
22pF
A6318 Adjustable LDO regulator Programming
REV2.1
- JAN 2010 RELEASED, FEB 2014 UPDATED -
- 9 -
AITSEMI [ AiT Semiconductor ]
