CM9142 Datasheet, PDF (1/14 Pages) California Micro Devices Corp – Two Group, 4 and 2, WLED Driver, Different Current Settings

PRELIMINARY
CM9142
Two Group, 4 and 2, WLED Driver, Different Current Settings
Features
• 2.9V to 6V input voltage range
• Powers two display backlight and/or flash WLEDs
• Low external parts count, requires no inductor and
ballast resistors
• Low EMI and reflected ripple
• Adaptive charge pump ratio (1x or 1.5x) maximizes
efficiency at both high and low input voltage
• Precision current regulation for each output with
2% current matching at 20mA
• Programmable LED current via ISET1 and ISET2
• Independent Analog and PWM brightness control
• Independent current setting for each group
• Typical 500-kHz fixed switching frequency
• Supports up to 300mA, drives six LEDs regulated
to 50mA each
• Less than 10μA shutdown current
• Over-current and over-temperature protection
• Short circuit protection with auto shutdown
• Undervoltage lockout
• Soft-start limits start-up inrush current
• 16 lead TQFN package
• Optional RoHS compliant lead free package
Applications
• Drive white LEDs for STN/TFT Color LCD back-
lighting
• Cell phones, PDAs, with multiple displays
• Digital Still Cameras
• Flash for DSC
Product Description
The CM9142 is an adaptive fractional switched capaci-
tor (charge pump) regulator optimized for driving two
groups, 4 and 2, of white LEDs Each group features
individual ON/OFF controls and individually set current.
Each LED’s driver current is matched to within 2% for
uniform intensity. It supports an input voltage range of
2.9V to 6V, with undervoltage lockout. A failure detec-
tion circuit prevents the loss of power when one or
more LEDs fail (short or open). Internal over-tempera-
ture and over-current management provide short circuit
protection.
The CM9142 regulates up to 300mA of output current
to drive WLEDs, allowing up to 50mA per LED channel.
The maximum LED current for each group is pro-
grammed with external resistors. Master plus two inde-
pendent enable inputs allows for Analog and PWM
brightness control for each display. Either display can
also be used for a camera flash. In full shutdown mode,
the CM9142 draws only 10μA.
The CM9142 automatically selects the most efficient
charge pump ratio based on the operating voltage
requirement of the white LEDs. The proprietary design
architecture maintains high efficiency (> 80%), and at
low V_IN provides longer battery life. With a high V_IN, or
when the adapter is powered, it provides cool reliable
operation.
The CM9142 is available in a compact 16 lead TQFN
package. It can operate over the industrial temperature
range of -40°C to 85°C.
Typical Application
1.0uF
1.0uF
2.9V to 6.0V
C1P C1N C2P C2N
VIN
VOUT
1uF
LED1
Display 1
1uF
on ^Enable
off
R_SET1
R_SET2
PhotonIC^TM_LED2
CM9142
EN
LED3
ISET1
ISET2
GND
LED4
LED5
LED6
Display 2
© 2006 California Micro Devices Corp. All rights reserved.
04/26/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: [phone] l Fax: [phone] l www.cmd.com
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