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NCV8774

Ultra Low Iq 350 mA LDO Regulator

ON Semiconductor 

NCV8774

APPLICATIONS INFORMATION

The NCV8774 regulator is self−protected with internal

thermal shutdown and internal current limit. Typical

characteristics are shown in Figures 4 to 26.

Input Decoupling (Cin)

A ceramic or tantalum 0.1 mF capacitor is recommended

and should be connected close to the NCV8774 package.

Higher capacitance and lower ESR will improve the overall

line and load transient response.

If extremely fast input voltage transients are expected then

appropriate input filter must be used in order to decrease

rising and/or falling edges below 50 V/ms for proper

operation. The filter can be composed of several capacitors

in parallel.

Since TJ is not recommended to exceed 150°C, then the

NCV8774 soldered on 645 mm2, 1 oz copper area, FR4 can

dissipate up to 2.35 W when the ambient temperature (TA)

is 25°C. See Figure 27 for RqJA versus PCB area. The power

dissipated by the NCV8774 can be calculated from the

following equations:

PD + VinǒIq@IoutǓ ) IoutǒVin * VoutǓ

(eq. 2)

or

NOTE:

PD(max) ) ǒVout

Vin(max) +

Iout ) Iq

IoutǓ

(eq. 3)

Items containing Iq can be neglected if Iout >> Iq.

Output Decoupling (Cout)

The NCV8774 is a stable component and does not require

a minimum Equivalent Series Resistance (ESR) for the

output capacitor. Stability region of ESR vs Output Current

is shown in Figure 17. The minimum output decoupling

value is 1 mF and can be augmented to fulfill stringent load

transient requirements. The regulator works with ceramic

chip capacitors as well as tantalum devices. Larger values

improve noise rejection and load regulation transient

response.

Thermal Considerations

As power in the NCV8774 increases, it might become

necessary to provide some thermal relief. The maximum

power dissipation supported by the device is dependent

upon board design and layout. Mounting pad configuration

on the PCB, the board material, and the ambient temperature

affect the rate of junction temperature rise for the part. When

the NCV8774 has good thermal conductivity through the

PCB, the junction temperature will be relatively low with

high power applications. The maximum dissipation the

NCV8774 can handle is given by:

ƪ ƫ TJ(max) * TA

PD(max) +

RqJA

(eq. 1)

ORDERING INFORMATION

100

90

80

70

DPAK 1 oz

60

50

DPAK 2 oz

40

0

100 200 300 400 500 600 700

COPPER HEAT SPREADER (mm2)

Figure 27. Thermal Resistance vs. PCB Copper Area

Hints

Vin and GND printed circuit board traces should be as

wide as possible. When the impedance of these traces is

high, there is a chance to pick up noise or cause the regulator

to malfunction. Place external components, especially the

output capacitor, as close as possible to the NCV8774 and

make traces as short as possible.

Device

Output Voltage

Marking

Package

Shipping†

NCV8774DT50RKG

5.0 V

877450G

DPAK−3

(Pb−Free)

2500 /

Tape & Reel

NCV8774DT33RKG

3.3 V

877433G

DPAK−3

(Pb−Free)

2500 /

Tape & Reel

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

http://onsemi.com

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