NCP1521AMUTBG datasheet(10/17 Pages) ONSEMI

No de pièce	NCP1521AMUTBG

Description	1.5 MHz, 600 mA, High?묮fficiency, Low Quiescent Current, Adjustable Output Voltage Step?묭own Converter

Download	17 Pages

Scroll/Zoom	100%

Fabricant	ONSEMI [ON Semiconductor]

Site Internet	http://www.onsemi.com

Logo

10 / 17 page

NCP1521

http://onsemi.com

10

APPLICATION INFORMATION

Output Voltage Selection

The output voltage is programmed through an external

resistor divider connected from VOUT to FB then to GND.

For low power consumption and noise immunity, the

resistor from FB to GND (R2) should be in the

[100 k−600 k] range. If R2 is 200 k given the VFB is 0.6 V,

the current through the divider will be 3.0

mA.

The formula below gives the value of VOUT, given the

desired R1 and the R1 value:

VOUT + VFB

(1

) R1

R2

)

(eq. 2)

• VOUT: Output Voltage (Volts)

• VFB: Feedback Voltage = 0.6 V

• R1: Feedback Resistor from VOUT to FB

• R2: Feedback Resistor from FB to GND

Input Capacitor Selection

In PWM operating mode, the input current is pulsating

with large switching noise. Using an input bypass capacitor

can reduce the peak current transients drawn from the

input supply source, thereby reducing switching noise

significantly. The capacitance needed for the input bypass

capacitor depends on the source impedance of the input

supply.

The maximum RMS current occurs at 50% duty cycle

with maximum output current, which is IO, max/2.

For NCP1521, a low profile, low ESR ceramic capacitor

of 4.7

mF should be used for most of the cases. For effective

bypass results, the input capacitor should be placed as close

as possible to the VIN pin.

Table 1. List of Input Capacitor

Murata

GRM188R60J475KE

GRM21BR71C475KA

Taiyo Yuden

JMK212BY475MG

TDK

C2012X5ROJ475KB

C1632X5ROJ475KT

Output L−C Filter Design Considerations

The NCP1521 is built in 1.5 MHz frequency and uses

current mode architecture. The correct selection of the

output filter ensures good stability and fast transient

response.

Due to the nature of the buck converter, the output L−C

filter must be selected to work with internal compensation.

For NCP1521, the internal compensation is internally fixed

and it is optimized for an output filter of L = 2.2

mH and

COUT = 10

mF.

The corner frequency is given by:

fc +

1

2

p L

COUT

(eq. 3)

+

1

2

p 2.2 mH

10

mF

+ 34 kHz

The device is intended to operate with inductance values

between 1.0

mH and maximum of 4.7 mH.

If the corner frequency is moved, it is recommended to

check the loop stability depending on the output ripple

voltage accepted and output current required. For lower

frequency, the stability will be increased; a larger output

capacitor value could be chosen without critical effect on

the system. On the other hand, a smaller capacitor value

increases the corner frequency and it should be critical for

the system stability. Take care to check the loop stability.

The phase margin is usually higher than 45

°.

Table 2. L−C Filter Example

Inductance (L)

Output Capacitor (Cout)

1.0

mH

22

mF

2.2

mH

10

mF

4.7

mH

4.7

mF

Inductor Selection

The inductor parameters directly related to device

performances are saturation current and DC resistance and

inductance value. The inductor ripple current (ÄIL)

decreases with higher inductance:

DIL +

VOUT

L

fSW

1−

VOUT

VIN

(eq. 4)

DIL peak to peak inductor ripple current

L inductor value

fSW switching frequency

The saturation current of the inductor should be rated

higher than the maximum load current plus half the ripple

current:

IL(MAX) + IO(MAX) )

DIL

2

(eq. 5)

DIL(MAX) Maximum inductor current

DIO(MAX) Maximum Output current

The inductor’s resistance will factor into the overall

efficiency of the converter. For best performances, the DC

resistance should be less than 0.3

W for good efficiency.

Numéro de pièce similaire - NCP1521AMUTBG

Fabricant	No de pièce	Fiches technique	Description
ON Semiconductor	NCP1521	1Mb / 20P	High Efficiency DC-DC Converters Rev.2, Jun-2006
	NCP1521	3Mb / 4P	AC-DC Offline Switching Controllers/Regulators Rev.0, Jun-2005
	NCP1521B	219Kb / 14P	1.5 MHz, 600 mA Step?묭own DC?묭C Converter March, 2007 ??Rev. 0
	NCP1521BEVB	148Kb / 1P	Test Procedure for the NCP1521B Evaluation Board 5/31/2007
	NCP1521BMUTBG	219Kb / 14P	1.5 MHz, 600 mA Step?묭own DC?묭C Converter March, 2007 ??Rev. 0

More results

Description similaire - NCP1521AMUTBG

Fabricant	No de pièce	Fiches technique	Description
ON Semiconductor	NCP9001	186Kb / 12P	1.5 MHz, 600 mA, High?묮fficiency, Low Quiescent Current, Adjustable Output Voltage Step?묭own Converter August, 2006 ??Rev. 2
	NCP1522	155Kb / 17P	3.0 MHz, 600 mA, High?묮fficiency, Low Quiescent Current, Adjustable Output Voltage Step?묭own Converter August, 2006 ??Rev. 3
	NCP1523	261Kb / 16P	3 MHz, 600 mA, High?묮fficiency, Adjustable Output Voltage Step?뭗own Converter February, 2007 ??Rev. 2
	NCP1523	302Kb / 14P	3 MHz, 600 mA, High?묮fficiency, Adjustable Output Voltage Stepdown Converter August, 2006 ??Rev. 0
	NCP1521B	219Kb / 14P	1.5 MHz, 600 mA Step?묭own DC?묭C Converter March, 2007 ??Rev. 0
	NCP1526	292Kb / 16P	400 mA, 1.2 V, High?묮fficiency, Step?묭own Converter with Low Noise Voltage Regulator Optimized for RF Module July, 2006 ??Rev. 0
	NCP1521B	187Kb / 14P	1.5 MHz, 600 mA Step-Down DC-DC Converter December, 2010 ??Rev. 5
Linear Technology	LTC3807EFE	436Kb / 6P	Low Quiescent Current, High Voltage Step-Down Converter
ON Semiconductor	LM2574	296Kb / 26P	0.5 A, Adjustable Output Voltage, Step?묭own Switching Regulator August, 2006 ??Rev. 8
ON Semiconductor	LM2575	364Kb / 28P	1.0 A, Adjustable Output Voltage, Step?묭own Switching Regulator November, 2005 ??Rev. 8

More results

NCP1521AMUTBG Fiches technique(PDF) 10 Page - ON Semiconductor

NCP1521AMUTBG Fiches technique(HTML) 10 Page - ON Semiconductor

Numéro de pièce similaire - NCP1521AMUTBG

Description similaire - NCP1521AMUTBG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Fiches technique Télécharger

Lien URL