ZXLD1100 Datasheet, PDF (1/16 Pages) Zetex Semiconductors – ADJUSTABLE LED DRIVER WITH INTERNAL SWITCH AND OPEN CIRCUIT PROTECTION IN SC70-6

ZXLD1100
ADJUSTABLE LED DRIVER WITH INTERNAL SWITCH AND OPEN
CIRCUIT PROTECTION IN SC70-6
DESCRIPTION
The ZXLD1100 is a PFM inductive boost converter
designed for driving 2, 3 or 4 series connected white
LEDs from a Li-Ion cell and up to 8 LEDs from a 5V
supply. The device operates from an input supply of
between 2.5V and 5.5V and provides an adjustable
output current of up to 50mA.
The ZXLD1100 includes the output switch and peak
current sense resistor, and can operate with a
maximum output voltage of 28V.
Quiescent current is typically 60␮A and a shutdown
function is provided to reduce this current to less than
500nA in the 'off' state.
Output current can be adjusted by applying a PWM
control signal to the 'Enable' pin. Depending upon the
control frequency, this will provide either a continuous
or a 'chopped' output current. The PWM filter
components are contained within the chip.
The ZXLD1100 contains an internal avalanche diode to
protect the output switch. This allows the device to
operate indefinitely if the load is open circuit. Input
supply current during this condition is less than 1mA.
The device is assembled in a low profile SC70-6 pin
package with industry standard pinout.
ADVANCED FEATURES
• Internal 30V NDMOS switch, current sense and
open circuit protection
• True Analog Dimming via PWM
FEATURES
• Low profile SC70 6 pin package
• Internal PWM filter for flicker free output
• High efficiency (80% typ)
• Wide input voltage range: 2.5V to 5.5V
• Up to 50mA output current
• Low quiescent current: (60␮A typ)
• 500nA maximum shutdown current
• Up to 1MHz switching frequency
• Low external component count
• Inherently matched LED currents
APPLICATIONS
• Mobile phones
• Digital cameras
• PDAs
• LCD modules
• Portable internet appliances
• Palmtop computers
TYPICAL APPLICATION CIRCUIT
PIN CONNECTIONS
ISSUE 4 - JULY 2004
1
SEMICONDUCTORS