TS39500/1/2/3

5A Ultra Low Dropout Positive Voltage Regulator

5/12

Version: A07

Application Information

The TS39500/1/2/3 are high performance with low dropout voltage regulator suitable for moderate to high current and

voltage regulator application. Its 630mV dropout voltage at full load and over temperature makes it especially valuable

in battery power systems and as high efficiency noise filters in post regulator applications. Unlike normal NPN

transistor design, where the base to emitter voltage drop and collector to emitter saturation voltage limit the minimum

dropout voltage, dropout performance of the PNP output of these devices is limited only by low Vce saturation voltage.

The TS39500/1/2/3 is fully protected from damage due to fault conditions. Linear current limiting is provided. Output

current during overload conditions is constant. Thermal shutdown the device when the die temperature exceeds the

maximum safe operating temperature. Transient protection allows device survival even when the input voltage spikes

above and below nominal. The output structure of these regulators allows voltages in excess of the desired output

voltage to be applied without reverse current flow.

Output Capacitor Requirement

The TS39500/1/2/3 requires an output capacitor to maintain stability and improve transient response is necessary. The

value of this capacitor is dependent upon the output current, lower currents allow smaller capacitors. TS39500/1/2/3

output capacitor selection is dependent upon the ESR of the output capacitor to maintain stability. When the output

capacitor is 10uF or greater, the output capacitor should have an ESR less than 2Ω. This will improve transient

response as well as promote stability. Ultra low ESR capacitors (<100mΩ), such as ceramic chip capacitors, may

promote instability. These very low ESR levels may cause an oscillation and/or under damped transient response. A

low ESR solid tantalum capacitor works extremely well and provides good transient response and stability over

temperature aluminum electrolytes can also be used, as long as the ESR of the capacitor is <2Ω. The value of the

output capacitor can be increased without limit. Higher capacitance values help to improve transient response and

ripple rejection and reduce output noise.

Input Capacitor Requirement

An input capacitor of 1uF or greater is recommended when the device is more than 4” away from the bulk AC supply

capacitance or when the supply is a battery. Small, surface mount, ceramic chip capacitors can be used for bypassing.

Larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity

of the output voltage.

Minimum Load Current

The TS39500/1/2/3 is specified between finite loads. If the output current is too small leakage currents dominate and

the output voltage rises. A 10mA minimum load current is necessary for proper regulation.

Adjustable Regulator Design

The adjustable regulator versions (TS39502) is allow to programming the output voltage anywhere between 1.25 and

the 16V maximum operating rating of the family.

Two resistors are used. Resistors can be quite large up to 1MΩ, because of the very high input impedance and low

bias current of the sense comparator, the resistor values are calculated by:

Where Vout is the desired output voltage. Above application circuit shows component definition. Applications with

widely varying load currents may scale the resistors to draw the minimum load current required for proper operation.