1.5A Ultra Low Dropout Linear Regulator
TJ3965
Oct. 2006 – R1.2.1
8/9
HTC
APPLICATION INFORMATION
Output Adjustment (Adjustable Version)
An adjustable output device has output voltage range of 1.145V to 5.0V.
To obtain a desired output
voltage, the following equation can be used with R1 resistor range of 10k
to 220k
−
=
1
145
.
1
1
2
OUT
V
R
R
To enhance output stability, a capacitor of 68pF to 100pF can be placed in series with VOUT and ADJ.
SENSE Pin
In applications where the regulator output is not very close to the load, the TJ3965 can provide better
remote load regulation characteristics using the SENSE pin.
TJ3965 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 VOUT pin. Connecting the sense pin to the remote load will provide regulation
at the remote load because the TJ3965 regulates the voltage at the sense pin when the sense option pin
is used.
Maximum Output Current Capability
The TJ3965 can deliver a continuous current of 1.5A 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 1.5A
may be still undeliverable due to the restriction of the power dissipation of TJ3965.
Under all possible
conditions, the junction temperature must be within the range specified under operating conditions.
The temperatures over the device are given by:
TC = TA + PD X θCA
TJ = TC + PD X θJC
TJ = TA + PD X θJA
where TJ is the junction temperature, TC is the case temperature, TA is the ambient temperature, PD is the
total power dissipation of the device, θCA is the thermal resistance of case-to-ambient, θJC is the thermal