3A Ultra Low Dropout Linear Regulator
Output Adjustment (Adjustable Version)
TJ4230
An adjustable output device has output voltage range of 0.8V to 5.0V. The operating condition of V
IN
and
the operating characteristics of V
OUT
depend on the dropout voltage performance in accordance with
output load current presented at Fig. 7. To obtain a desired output voltage, the following equation can be
used with R1 resistor range of 100Ω to 50kΩ.
VIN
C
IN
10uF
V
IN
V
OUT
VOUT
CFF
ADJ
R1
R2
C
OUT
10uF
TJ4230
EN
EN
GND
⎛
V
⎞
R
2
=
R
1
⎜
OUT
−
1
⎟
⎝
0
.
8
⎠
Fig. 4. Application for Adjustable Output Voltage
To enhance output stability, a feed-forward capacitor of 10nF to 1uF can be placed in series with V
OUT
and
ADJ.(Refer to "Component Selection" Section)
SENSE Pin
In applications where the regulator output is not very close to the load, the TJ4230 can provide better
remote load regulation characteristics using the SENSE pin. TJ4230 regulates the voltage at the output
pin. Hence, the voltage at the remote load will be lower than the voltage at the output pin as a value of
the voltage drop across the trace series resistance. If the sense option pin is not required, the sense pin
must be connected to the V
OUT
pin. Connecting the sense pin to the remote load will provide regulation
at the remote load because the TJ4230 regulates the voltage at the sense pin when the sense option pin
is used.
Fig. 5. Conventional Linear Regulator Application
Maximum Output Current Capability
Fig.6. Remote Load Sense Application
The TJ4230 can deliver a continuous current of 3A over the full operating junction temperature range.
However, the output current is limited by the restriction of power dissipation which differs from packages.
A heat sink may be required depending on the maximum power dissipation and maximum ambient
temperature of application. With respect to the applied package, the maximum output current of 3A may
be still undeliverable due to the restriction of the power dissipation of TJ4230. Under all possible
conditions, the junction temperature must be within the range specified under operating conditions.
The temperatures over the device are given by:
T
C
= T
A
+ P
D
X
θ
CA
T
J
= T
C
+ P
D
X
θ
JC
T
J
= T
A
+ P
D
X
θ
JA
Apr. 2011 – Rev. 1. 0
7/9
HTC
HTC [ HTC KOREA TAEJIN TECHNOLOGY CO. ]
