CM9321 Datasheet, PDF (1/11 Pages) California Micro Devices Corp – Asymmetrical High Efficiency Three Channel Boost LED/OLED Driver

PRELIMINARY
CM9321
Asymmetrical High Efficiency Three Channel Boost LED/OLED Driver
Features
• Integrated WLED and OLED driver
• 2.7V to 6V input voltage range
• Up to 85% typical efficiency even for asymmetrical
channel loads in terms of LED number, LED current
and LED dropout
• Excellent 5 series x 2 parallel WLED drive capability
(35 mA per channel)
• OLED channel with up to 18V/30 mA capability
• Independent current/voltage setting using external
low power resistors for each channel (no ballast resis-
tors)
• No external frequency compensation needed
• Low (<1%) LED output ripple voltage and current
• Input undervoltage lockout and output over-voltage
protection
• 1 MHz fixed switching frequency (0.5 MHz option
available)
• Uses small inductor and ceramic capacitors
• Integrated 0.3 Ω internal power switch
• Disconnects LEDs during shutdown
• Low profile TQFN-16 package
• Optional RoHS compliant lead free packaing
Applications
• Drives white LED backlighting and OLED
• Cell phones
• Digital Cameras
• PDA, GPS, MP3 players
• Handheld devices
Product Description
The CM9321 is a high frequency, three-channel inductor-
based PWM boost regulator specifically designed for con-
stant current white LED and constant voltage OLED drive
applications. With a maximum 19V/140mA output capabil-
ity, the circuit can drive up to 10 WLEDs (5 series x 2 par-
allel) and one OLED, allowing up to 35 mA per channel.
With an input voltage range from 2.7V to 6.0V, it can oper-
ate from a single cell Li-Ion battery.
The proprietary FlexBoost™ architecture (patent pending)
provides high efficiency (typical 85%) for a wide input volt-
age range, even for asymmetrical channel loads in term of
LED number, LED current and LED type. A standard (non-
interleave) version is also available using a MODE selec-
tion pin (not availalbe fo mass production). The maximum
LED current and OLED voltage for each channel is inde-
pendently programmed with external low-power resistors
(no ballast resistors needed).
A 1 MHz constant frequency PWM saves board space,
allowing small, low-cost external components which per-
mits designers to avoid sensitive IF bands in RF applica-
tions. The output over-voltage protection circuit prevents
damage in the case of a high impedance output (e.g.
faulty LED). The controlled current limit circuit prevents
large inductor current spikes, even at start-up. To avoid
possible leakage currents the EN control pin disconnects
the LEDs from ground during shutdown.
The CM9321 is available in a compact TQFN-16 package.
It can operate over the industrial temperature range of -
40°C to 85°C.
Typical Application
V_{IN 2.7V to 6.0V}
C_IN
10 uF/10V
on (by default)
off
Enable
16
15 14 13
C_REF
R_{SET 1 1}
ISET1
22K
VOUT ¹²
2 _{LED1 PhotonICTM SW} 11
3
VREF
CM9321
10
GND
R_{SET 21}
20K
4 _VSET2
9 interlv (by default)
MODE
no-interlv
R_{SET 22 91K}
1 uF/6.3V
5
R_{SET 3}
22K
C_OLED
10 uF/16V
6
7
8
L1
4.7 uH
D1
1A/20V
Channel
CH1
CH2 CH3
OLED
V_OUT
C_OUT
1 uF/16V
© 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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