NCP512 Просмотр технического описания (PDF) - ON Semiconductor

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NCP512

Voltage Regulator - CMOS, Low Iq 80 mA

ON Semiconductor 

NCP512

APPLICATIONS INFORMATION

A typical application circuit for the NCP512 series is

shown in Figure 1, front page.

Input Decoupling (C1)

A 1.0 mF capacitor either ceramic or tantalum is

recommended and should be connected close to the NCP512

package. Higher values and lower ESR will improve the

overall line transient response.

TDK capacitor: C2012X5R1C105K, or C1608X5R1A105K

Output Decoupling (C2)

The NCP512 is a stable regulator and does not require any

specific Equivalent Series Resistance (ESR) or a minimum

output current. Capacitors exhibiting ESRs ranging from a

few mW up to 5.0 W can thus safely be used. The minimum

decoupling value is 1.0 mF and can be augmented to fulfill

stringent load transient requirements. The regulator accepts

ceramic chip capacitors as well as tantalum capacitors.

Larger values improve noise rejection and load regulation

transient response.

TDK capacitor: C2012X5R1C105K, C1608X5R1A105K,

or C3216X7R1C105K

Enable Operation

The enable pin will turn on the regulator when pulled high

and turn off the regulator when pulled low. These limits of

threshold are covered in the electrical specification section

of this data sheet. If the enable is not used then the pin should

be connected to Vin.

Hints

Please be sure the Vin and GND lines are sufficiently

wide. When the impedance of these lines is high, there is a

chance to pick up noise or cause the regulator to

malfunction.

Set external components, especially the output capacitor,

as close as possible to the circuit, and make leads as short as

possible.

Thermal

As power across the NCP512 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 also the ambient

temperature effect the rate of temperature rise for the part.

This is stating that when the NCP512 has good thermal

conductivity through the PCB, the junction temperature will

be relatively low with high power dissipation applications.

The maximum dissipation the package can handle is

given by:

PD

+

TJ(max) *TA

RqJA

If junction temperature is not allowed above the

maximum 125°C, then the NCP512 can dissipate up to

250 mW @ 25°C.

The power dissipated by the NCP512 can be calculated

from the following equation:

Ptot + ƪVin * Ignd (Iout)ƫ ) [Vin * Vout] * Iout

or

VinMAX

+

Ptot ) Vout * Iout

Ignd ) Iout

If an 80 mA output current is needed then the ground

current from the data sheet is 40 mA. For an NCP512 (3.0 V),

the maximum input voltage will then be 6.12 V.

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