1A Ultra Low Dropout Linear Regulator

TJ3964

Dec. 2009 – Rev. 1.1

- 9 -

HTC

Output Capacitor

The TJ3964 requires a proper output capacitance to maintain stability and improve transient response

over current. The ESR of the output capacitor within the limits of 0.5Ω to 10Ω is required. A minimum

capacitance value of 22µF of tantalum or aluminum electrolytic capacitor is recommended. In a case of

ceramic capacitor, a minimum capacitance value of 10µF is required and additional resistance of

minimum 1Ω should be added with the output capacitor in series to maintain its minimum ESR. The

resistance and capacitance have to be varied upon the load current.

VOUT

ADJ

GND

R2

R1

22µF

OUTPUT

+

-

VOUT

ADJ

GND

R2

R1

10µF

OUTPUT

Additional Resistance

Maximum Output Current Capability

The TJ3964 can deliver a continuous current of 1A 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 1A may

be still undeliverable due to the restriction of the power dissipation of TJ3964. Under all possible

conditions, the junction temperature must be within the range specified under operating conditions.

The temperatures over the device are given by:

The total power dissipation of the device is given by:

formula:

TJ3964 is available in SOT23-5, SOT-223, TO-252 and SOP-8 packages. The thermal resistance

calculated above is as described in Table 1, no heat sink is needed since the package can dissipate

heat sink or proper area of copper plane is required.