Diodes ZXLD1350 - Manual (Page 2)

ZXLD1350
30V 350mA LED DRIVER with AEC-Q100
ZXLD1350
Document number: DS33468 Rev. 8 - 2
2 of 22
www.diodes.com
March 2011
© Diodes Incorporated
A Product Line of
Diodes Incorporated
Block Diagram
Figure 1. Block diagram – Pin Connection
Pin Description
Name Pin No. Description
LX 1 Drain of NDMOS switch
GND 2 Ground (0V)
ADJ 3
Multi-function On/Off and brightness control pin:
• Leave floating for normal operation.(V
ADJ
= V
REF
=1.25V giving nominal average output current
I
OUTnom
=0.1/R
S
)
• Drive to voltage below 0.2V to turn off output current
• Drive with DC voltage (0.3V<V
ADJ
<2.5V) to adjust output current from 25% to 200%
(†)
of I
OUTnom
• Drive with PWM signal from open-collector or open-drain transistor, to adjust output current.
Adjustment range 25% to 100% of I
OUTnom
for f>10kHz and 1% to 100% of I
OUTnom
for f<500Hz
• Connect a capacitor from this pin to ground to increase soft-start time. (Default soft-start time=0.5ms.
Additional soft-start time is approx.0.5ms/nF)
I
SENSE
4
Connect resistor R
S
from this to V
IN
to define nominal average output current I
OUTnom
=0.1/R
S
(Note: R
SMIN
=0.27V with ADJ pin open circuit)
V
IN
5
Input voltage (7V to 30V). Decouple to ground with 1µF of higher X7R ceramic capacitor close to
device
MN
-
+
V
IN
Comparator
R1
R2
R3
GND
-
+
LX V IN I SENSE
Current sense circuit
V
IN
ADJ
R S
L1
D1
5V Voltage
regulator
Shutdown
circuit
Vref
200k
1.25V
4KHz
C1