NCP5603

http://onsemi.com

4

PIN FUNCTION DESCRIPTION

Pin

Symbol

Type

Description

1

OUTPUT, PWR

This pin supplies the regulated voltage to the external LED. Since high current transients

are present in this pin, care must be observed to avoid voltage spikes in the system. Good

high frequency layout technique must be observed.

2

C1N

POWER

with C1P, pin 9. Using low ESR ceramic capacitor is recommended to optimize the Charge

Pump efficiency.

3

POWER

This pin shall be connected to the power source, and must be decoupled to Ground by a

low ESR capacitor (2.2

mF/6.3 V ceramic or better (see Note 1)).

4

Fsel

INPUT, Digital

This pin is used to program the operating frequency:

Fsel = 0

→ Fop = 262 kHz

Fsel = 1

→ Fop = 650 kHz

5

Vsel

INPUT, Digital

This pin setup the output voltage:

Vsel = 0

Vsel = 1

6

EN/PWM

INPUT, Digital

This pin controls the activity of the NCP5603 chip:

EN/PWM = Low

→ the chip is deactivated, the load is disconnected

EN/PWM = High

→ the chip is activated and the load is connected to the

regulated output current.

The NCP5603 can operate either in a continuous mode (EN/PWM = High), or can be

controlled by a PWM pulse applied to EN/PWM to dim the output light. When EN/PWM is

Low, the external load is disconnected from the converter, providing a very low standby

current. The pull down built−in resistance makes sure the chip is deactivated even if the

EN/PWM pin is disconnected (see Note 2).

7

C2N

POWER

with C2P, pin 10. Using low ESR ceramic capacitor is recommended to optimize the

Charge Pump efficiency.

8

GND

GROUND

This pin combines the Signal ground and the Power ground and must be connected to the

system ground. Using good quality ground plane is mandatory to avoid spikes on the logic

signal lines.

9

C1P

POWER

with C1N, pin 2. Using low ESR ceramic capacitor is recommended to optimize the Charge

Pump efficiency.

10

C2P

POWER

One side of the external charge pump capacitor is connected to this pin, associated with

C2N, pin 7. Using low ESR ceramic capacitor is recommended to optimize the Charge

Pump efficiency.

1. Using ceramic 16 V working voltage capacitors is recommended to compensate the DC bias effect encountered with such type of capacitors.

2. Any external impedance connected to pin 6 shall be 10 k

W or higher.