Datasheet

NCP5603
http://onsemi.com
4
PIN FUNCTION DESCRIPTION
Pin Symbol Type Description
1 V
out
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 One side of the external charge pump capacitor (C
FLY
) is connected to this pin, associated
with C1P, pin 9. Using low ESR ceramic capacitor is recommended to optimize the Charge
Pump efficiency.
3 V
bat
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 → V
out
= 4.5 V
Vsel = 1 → V
out
= 5.0 V
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 One side of the external charge pump capacitor (C
FLY
) is connected to this pin, associated
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 One side of the external charge pump capacitor (C
FLY
) is connected to this pin, associated
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 kW or higher.