NCV59744

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8

APPLICATIONS INFORMATION

The NCV59744 dual−rail very low dropout voltage

regulator is using NMOS pass transistor for output voltage

The use of an NMOS pass transistor offers several

advantages in applications. Unlike a PMOS topology

devices, the output capacitor has reduced impact on loop

stability. Vin to Vout operating voltage difference can be

very low compared with standard PMOS regulators in very

low Vin applications.

The NCV59744 offers programmable smooth monotonic

start-up. The controlled voltage rising limits the inrush

current what is advantageous in applications with large

capacitive loads. The Voltage Controlled Soft Start timing is

programmable by external Css capacitor value.

The Enable (EN) input is equipped with internal

hysteresis and deglitch filter.

Open Drain type Power Good (PG) output is available for

Vout monitoring and sequencing of other devices.

NCV59744 is a Adjustable linear regulator. The required

Output voltage can be adjusted by two external resistors.

Typical application schematics is shown in Figure 16.

Figure 16. Typical Application Schematics

V

1

) R

NCV59744

Dropout Voltage

specified.

percents specified in the Electrical Characteristics table.

Electrical Characteristics table.

Input and Output Capacitors

The device is designed to be stable for all available types

and values of output capacitors

≥ 2.2 mF. The device is also

stable with multiple capacitors in parallel, which can be of

any type or value.

In applications where no low input supply impedance is

available (PCB inductance in Vin and/or Vbias inputs as an

example) the recommended Cin and Cbias value is 1

mF or

greater. Ceramic or other low ESR capacitors are

recommended. For the best performance all capacitors

should be connected to the NCV59744 respective pins

directly in the device PCB copper layer, not through vias

having not negligible impedance.

Enable Operation

The enable pin will turn the regulator on or off. The

threshold limits are covered in the electrical characteristics

table in this data sheet. If the enable function is not to be used

Output Noise

When the NCV59744 device reaches the end of the

Soft−Start cycle, the Soft Start capacitor is switched to serve

as a Noise filtering capacitor.

Output Voltage Adjust

The output voltage can be adjusted from 0.8 V to 3.6 V

using resistors divider between the output and the FB input.

Recommended resistor values for frequently used voltages

can be found in the Table 6.

Programmable Soft−Start

The Soft-Start ramp time depends on the Soft Start

The Soft –Start time can be calculated using following

equations:

or in more practical units

where

Capacitor values for frequently used Soft-Start times can be

found in the Table 7.

before new Soft-Start cycle is not guaranteed.

Current Limitation

The internal Current Limitation circuitry allows the

device to supply the full nominal current and surges but

protects the device against Current Overload or Short.

Thermal Protection

Internal thermal shutdown (TSD) circuitry is provided to

protect the integrated circuit in the event that the maximum

junction temperature is exceeded. When TSD activated , the

regulator output turns off. When cooling down under the low

temperature threshold, device output is activated again. This

TSD feature is provided to prevent failures from accidental

overheating.