Diodes AL8807A - Manual (Page 2)

AL8807A
Document number: DS35990 Rev. 2 - 2
2 of 20
www.diodes.com
March 2013
© Diodes Incorporated
AL8807A
Pin Descriptions
Pin Name
Pin Number
Function
SOT25 MSOP-8EP
SW 1 5, 6 Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI.
GND 2 2, 3 GND Pin
CTRL 3 4
LED current Analog Dimming Control Input. – No PWM dimming function.
Connected to internal 2.5V V
REF
via 50k Ω resistor. So if left open circuit V
CTRL
= V
REF
= 2.5V and 100%
LED current is achieved - giving nominal average output current I
OUTnom
= 0.1/R
S
For Analog dimming drive with analog voltage < 2.5V
(0.25V < V
CTRL
< 2.5V adjusts output current from 10% to 100% of I
OUTnom
. Device will dim the LED current
lower than this level but at reduced accuracy. Some devices will not totally turn off the LED current.
Soft-start can be implemented by connecting a capacitor to CTRL pin. The amount of soft-start is
dependent on ramp-up of input supply voltage and capacitor on CTRL pin. See apps section.
SET 4 1 Set Nominal Output Current Pin. Configure the output current of the device.
V
IN
5 8
Input Supply Pin. Must be locally decoupled to GND with > 2.2µF X7R ceramic capacitor – see
applications section for more information.
EP — EP
Exposed pad/TAB.
It should be connected to GND and thermal mass for enhanced thermal impedance.
It should not be used as electrical ground conduction path.
N/C — 7 No connection – may be connected to GND.
Functional Block Diagram