Dec 7-06

SP7619 Evaluation Board Manual

© 2006 Sipex Corporation

Page 2 of 4

INTRODUCTION

The SP7619 is a linear low side constant current driver designed to source two preset currents of

200mA/500mA (SP7619), 200mA/700mA (SP7619A)

CTRL pin to high or low. Dimming or shutdown can be done by feeding a PWM signal to the EN pin. Fast

EN turn-on/off time allows for very fast PWM dimming frequencies, completely eliminating flicker. The

driver acts as a current source ensuring constant LED current for a range of input voltage. The SP7619

allows for customer implementation of the lowest cost LED driver for a variety of applications. Internal

circuitry maintains the preset constant current output for a wide voltage range at the LED input. The built-

in thermal protection automatically stops LED current to prevent overheating. A timeout function serves

as a fail safe, shutting down the output for currents greater than 266mA after 4 seconds of continuous

operation if the enable input is not cycled.

Capacitor C1 is a decoupling capacitor. Resistor R1 is used to hold the device in a Sleep Mode at power

on if the ENABLE pin isn’t connected to Vin voltage. The SP7619 devices don’t have internal pull-

up/down resistors at the EN input and should be connected either to Vin or Ground. If the EN pin isn’t

used for modulation, it may be connected to Vin voltage directly using switch S1. Push button S2 is used

to set LED current. Low output current is set by default using resistor R2. To set high output current

value, connect the CTRL pin to Vcc (push button).

USING THE EVALUATION BOARD

1) Powering Up the SP7619 Circuit

The SP7619 Evaluation Board can be powered from a 4.5V power supply or from 3 alkaline cells.

Connect the 4.5V source pin with a short lead directly to the “Vin” and -4.5V /GND pin to the “GND”

posts. Connect the ENABLE pin to Vin voltage using shunt S1 (ON position).

2) Selecting the output current

The LED current may be set at 500 (700) mA by connecting the CTRL pin to the Vin voltage (push button

S2) or at 200 mA by connecting it to the ground (by default) respectively.*

The device provides high output current for 4 seconds only after setting the CTRL pin HIGH to protect

the LED. After that the device will go into shutdown mode.

Set the ENABLE pin LOW (switch S1 in position OFF) and then after that set it HIGH (S1 position ON) to

start the device again.

3) Dimming

The SP7619 can be pulse width modulated using the EN pin. Set switch S1 in the OFF position. Connect

the EN pin to the pulse generator with desired modulation frequency (positive pulse with amplitude from

2.4 to Vin voltage range). Changing the pulse duty cycle changes the average LED current.

Recommended modulation frequencies are from 100Hz to 2kHz with 10 – 90% duty cycle.

*