ZXLD1350 Datasheet, PDF (1/2 Pages) Zetex Semiconductors – 350mA LED driver with internal switch

ZXLD1350 Advance information
350mA LED driver with internal switch
Description
The ZXLD1350 is a continuous mode inductive step-
down converter, designed for driving single or multiple
series connected LEDs efficiently from a voltage
source higher than the LED voltage. The device
operates from an input supply between 7V and 30V
and provides an externally adjustable output current of
up to 350mA. Depending upon supply voltage and
external components, this can provide up to 8 watts of
output power.
The ZXLD1350 includes the output switch and a high-
side output current sensing circuit, which uses an
external resistor to set the nominal average output
current.
The ADJ pin will accept either a DC voltage or a PWM
waveform. Depending upon the control frequency, this
will provide either a continuous or a gated output
current. The PWM filter components are contained
within the chip.
The PWM filter provides a soft-start feature by
controlling the rise of input/output current. The soft-
start time can be increased using an external capacitor
from the ADJ pin to ground.
Applying a voltage of 0.2V or lower to the ADJ pin
turns the output off and switches the device into a low
current standby state.
Output current can be adjusted above, or below the set The device is assembled in a TSOT23-5 pin package.
value, by applying an external control signal to the
‘ADJ’ pin.
Features
• Simple low parts count
• Internal 30V NDMOS switch
• 350mA output current
• Single pin on/off and brightness control using DC
voltage or PWM
• Internal PWM filter
• Soft-start
• High efficiency (up to 95%*)
• Wide input voltage range: 7V to 30V
• 40V transient capability
• Output shutdown
• Up to 1MHz switching frequency
• Inherent open-circuit LED protection
Applications
• Low voltage halogen replacement LEDs
• Automotive lighting
• Low voltage industrial lighting
• LED back-up lighting
• Illuminated signs
* Using standard external components as specified under electrical characteristics. Efficiency is dependent upon the number
of LEDs driven and on external component types and values.
Pin connections
Typical application circuit
TSOT23-5
Top view
Provisional issue 1 - April 2006
© Zetex Semiconductors plc 2005
www.zetex.com