CM9320 Datasheet, PDF (1/10 Pages) California Micro Devices Corp – Asymmetrical High Efficiency Two Channel Boost LED Driver

PRELIMINARY
CM9320
Asymmetrical High Efficiency Two Channel Boost LED Driver
Features
• 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
Applications
• Drives white LEDs for backlighting color LCD
• Cell phones
• MP3 players, PDA, GPS
• Digital Still Cameras
• LED flashlights
• Handheld devices
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.
Typical Application
V_{IN 2.7V to 6.0V}
C_IN
10 uF/10V
on (by default) Enable
off
R_SET1
22K
R_SET2
22K
1
ISET1
EN ¹⁰
2
LED1
VOUT ⁹
PhotonIC^TM
3 _NC
CM9320
8
SW
4 _ISET2
GND ⁷
5 _LED2
VIN ⁶
L1
4.7 uH
D1
1A, 20V
Channel
CH1 CH2
V_OUT
C_OUT
1 uF/16V
© 2006 California Micro Devices Corp. All rights reserved.
05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: [phone] l Fax: [phone] l www.cmd.com
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