LD1117-12-AA3-A-R UTC [Unisonic Technologies], LD1117-12-AA3-A-R Datasheet - Page 11

• Manufacturer Part Number: LD1117-12-AA3-A-R
• Description: LOW DROP FIXED AND ADJUSTABLE POSITIVE VOLTAGE REGULATORS
• Manufacturer: UTC [Unisonic Technologies]

LD1117/A
APPLICATION NOTE of LD1117/A ADJUSTABLE
The LD1117/A ADJUSTABLE has a reference voltage of between the OUT and ADJ pins. I
(120μA max.) and ΔI
R1 is normally fixed to 120Ω.
From figure 4 we obtain:
V
Usually R2 value is in the range of few KΩ, so the R2 X I
expression becomes: V
For better load regulation, realize a good Kelvin connection of R1 and R2 is important. Particularly R1
connection must be realized very close to OUT and ADJ pin, while R2 ground connection must be placed as
near as possible to the negative Load pin. Ripple rejection can be improved by introducing a 10μF electrolytic
capacitor placed in parallel to the R2 resistor (See Fig. 5)
OUT
=V
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
REF
+R2(I
V
FIG.5 Adjustable Output Voltage Application with improved Ripple Rejection.
IN
ADJ
10μF
+ I
ADJ
R1
OUT
is 1μA typ. (5μA max.).
)=V
+
=V
FIG.4 Adjustable Output Voltage Application Circuit
REF
REF
+ R2(I
(1+R2/R1)
IN
UTC LD1117/A
ADJ
+ V
ADJ
REF
R2
OUT
/ R1)=V
120Ω
REF
ADJ
R1
(1+R2/R1) + R2 x I
product could be neglected; then the above
LINEAR INTEGRATED CIRCUIT
V
REF
+
ADJ
10μF
.
V
OUT
ADJ
is 60μA typ.
QW-R102-006,Q
11 of 12