PRELIMINARY
CM9320
Asymmetrical High Efficiency Two Channel Boost LED Driver
Features
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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
Up to 100 mA/19V output current/voltage
Independent current setting using an external low
power resistor for each channel (no ballast resistors)
No external frequency compensation needed
Low (<1%) LED output voltage and current ripple
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 low ON-Resistance (0.3
Ω)
N-Chann el
MOSFET switch
Disconnects LEDs during shutdown
Low profile TDFN-10 package
Optional RoHS compliant lead free packaging
Product Description
The CM9320 is a high frequency, two-channel inductor-
based PWM boost regulator specifically designed for con-
stant current white LED drive applications. With a maxi-
mum 100 mA/19V output capability, the circuit can drive
up to 10 WLEDs (5 series x 2 parallel) allowing up to 35
mA per channel. With a typical input voltage range from
2.7V to 6.0V, it can be operated 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 terms
of LED number, LED current and LED type. The maximum
LED current for each channel is independently pro-
grammed with external low-power resistors (no ballast
resistors needed).
A 1 MHz constant frequency PWM saves board space,
allowing small, low-cost external components, permitting
designers to avoid sensitive IF bands in RF applications.
The output over-voltage protection circuit prevents dam-
age in 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 CM9320 is available in a compact TDFN-10 package.
It can operate over the industrial temperature range of -
40°C to 85°C.
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Applications
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Drives white LEDs for backlighting color LCD
Cell phones
MP3 players, PDA, GPS
Digital Still Cameras
LED flashlights
Handheld devices
Typical Application
V
IN
2.7V to 6.0V
10 uF/10V
off
on (by default)
L1
Enable
4.7 uH
D1
1A, 20V
V
OUT
C
OUT
1 uF/16V
C
IN
R
SET1
22K
1
2
ISET1
LED1
NC
ISET2
LED2
EN
VOUT
10
Channel
9
CH1
CH2
3
R
SET2
22K
5
4
PhotonIC
TM
CM9320
SW
GND
VIN
8
7
6
©
2006 California Micro Devices Corp. All rights reserved.
05/08/06
490 N. McCarthy Blvd., Milpitas, CA 95035-5112
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Tel: 408.263.3214
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Fax: 408.263.7846
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www.cmd.com
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CALMIRCO [ CALIFORNIA MICRO DEVICES CORP ]
