LX1990_05 Datasheet, PDF (1/11 Pages) Microsemi Corporation – Dual Programmable LED Current Sink

LX1990
TM
®
Dual Programmable LED Current Sink
DESCRIPTION
The LX1990 is a dual output current Light output from LED’s is proportional
sink optimized for driving light emitting to average current through them; they can
diodes. This low cost bipolar IC enables easily produce a brightness range of 500:1.
precise current regulation in LED However, color of emitted light is shifted by
display lighting applications, yet current amplitude. Color shift at low light
requires far fewer parts than discrete levels can be reduced by driving the LED’s
solutions. The LX1990 is supplied in a with a constant peak current while dimming
micro-miniature 6 lead MLP package with duty cycle control.
featuring a 3 x 3 mm footprint, a profile This is achieved by driving the I_SET
of less than 1mm, and much improved resistor with a PWM signal. A 500:1
thermal performance. Its two output sink brightness range can be achieved by
currents are accurately matched and choosing 270 Hz as the PWM frequency (to
require only one resistor to program. avoid optical beating with 50/60 Hz room
Program current is only 1% of the lights) and pulse width from 3.7
output currents, and quiescent current is milliseconds to 7.4 microseconds.
low, providing a very high efficiency The LX1990 features a shutdown mode
driver for battery-powered displays.
via the Enable pin. In this mode the
The LX1990 is based on a current- LX1990 consumes less than 1µA and holds
mirror architecture that transfers a the two open collector output stages off.
reference current produced at the I_SET This pin may also be used to pulse width
pin to each of two open-collector current modulate output current. See applications
sinking outputs. The output stages section for dimming details.
multiply this reference current by 100 to
sink independently regulated currents up
to 30 mA.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
KEY FEATURES
• Programmable Sink Current
0.1 to 30mA x 2 Channels
• Replaces Discrete Transistor
Circuitry With A Single Package
• 300mV Maximum Current Sink
Dropout Voltage at 20mA
• 2.7 to 5.5V Power Supply Input
• I_OUT Compliance Voltage from
0.1 to 10V_DC
• Enable Input With <1µA Sleep
Current
• Amplitude and PWM Dimming
• Current rise and fall time may
be controlled to reduce EMI
APPLICATIONS
• Cell Phone Display Illumination
• PDA White LED Display
Lighting
• Automotive Display Illumination
• Digital Still Camera
• Camcorders
• Consumer Electronics Front
Panels
PRODUCT HIGHLIGHT
5V
ON/OFF
R_SET
V_LOAD
VDD
ENA
I_OUTB
LX1990
ISET
I_OUTA
GND
Copyright © 2001
Rev. 1.0d, 2005-03-14
PACKAGE ORDER INFO
T_A (°C)
-40 to 85
Plastic MLP
LM _6-Pin
RoHS Compliant / Pb-free Transition DC: 0452
LX1990ILM
Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1990ILM-TR)
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
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