UTC1117 Datasheet, PDF (6/7 Pages) Hangzhou Youwang Electronics Co., Ltd – LOW DROPOUT POSITIVE VOLTAGE REGULATOR

UTC1117
LINEAR INTEGRATED CIRCUIT
4.Stability and Load Regulation
UTC1117 requires a capacitor from VOUT to GND to
provide compensation feedback to the internal gain stage.
This is to ensure stability at the output terminal. Typically, a
μ μ 10 F tantalum of 50 F aluminum electrolytic is sufficient.
Note: It is important that the ESR for this capacitor does _VIN
not exceed 0.5Ω.
The output capacitor does not have a theoretical upper
μ limit and increase stability. COUT=100 F or more is typical
for high current regulator design.
For the adjustable version, the best load regulation is
accomplished when the top for the resistor divider (R1) is
connected directly to the output pin of the UTC1117. When
so connected, RP is not multiplied by the divider ratio. For
fixed output versions, the top of R1 is internally connected to
the output and ground pin can be connected to low side of
the load.
3 IN
ADJ ^{OUT 2}
1
RP
Parasitic
Line Resistance
R1
RL
(connect R1
to case)
Connect
R2 to load
5.Thermal Consideration
The UTC1117 series contain thermal limiting circuitry designed to protect itself for over-temperature conditions,
maximum junction temperature ratings must not be exceeded. As mention in thermal protection section, we need to
consider all sources of thermal resistance between junction and ambient. It includes junction-to-case, case-to-heat-
sink interface and heat sink thermal resistance itself.
Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the
die. Proper mounting is required to ensure the best possible thermal flow from this area of the package to the heat
sink. The case of all devices in this series is electrically connected to the output. Therefore, if the case of the
device must be electrically isolated, a thermally conductive spacer is recommended.
ADVANCED APPLICATIONS
Adjustable Output Voltage
VIN
UTC1117ACCT
10µF
**
10µF
R2
R1
1K
2K
* Vo=1.5~3.45V
10µF
× *VO=Vref(1+R2/R1)+Iadj R2
**Optional for improved ripple rejection
YOUWANG ELECTRONICS CO.LTD
6