MIC3263
Six-Channel WLED Driver for
Backlighting Applications with
Flicker-Free Dimming
General Description
The MIC3263 is a high-efficiency Pulse Width Modulation
(PWM) boost switching regulator that is optimized for
constant-current WLED driver backlighting applications.
The MIC3263 drives six channels of up to ten WLEDs per
channel. Each channel is matched in current to within ±3%
for constant brightness across the screen and can be
programmed from 15mA to 30mA.
The MIC3263 provides a very flexible dimming control
scheme with better accuracy and noise immunity. The
dimming frequency can be set to any value between
100Hz and 20kHz by an external resistor. The dimming
ratio is determined by the duty cycle of a dimming ratio
control input signal and can be set to one of 16 levels with
a minimum ratio of 1%.The LED dimming current is set by
an external resistor to allow programming of LED current
between 15mA and 30mA.
The dimming ratio of the MIC3263 is fixed to 16 log levels
to better match the sensitivity of the human eye. Each of
the dimming levels has hysteresis to avoid skipping
between levels and allow for high noise immunity.
The MIC3263 has a programmable PWM switching
frequency from 400 KHz to 1.8 MHz to allow small inductor
sizes. The 6V to 40V wide input voltage range of MIC3263
allows direct operation from 6V or high cell count Li-Ion
batteries commonly found in notebook computers.
The MIC3263 is available in a low-profile 24-pin 4mm x
4mm MLF® package and has a junction temperature
range of
−40°C
to
+125°C.
Data sheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com
.
Features
•
•
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•
•
•
•
•
•
•
•
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6V to 40V wide input voltage range
Drives 6 channels of up to 10 white LEDs
Programmable WLED current from 15mA to 30mA
Highly reliable operation with open and short LEDs
Accurate 16 dimming log levels sets the dimming ratio
from 1% to 100%
Flicker-Free Dimming filters the jitter from the dimming
control input signal and eliminates dimming flicker
Allows external dimming control
Accurate LED channel current matching ±3%
Accurate initial LED current setting ±2%
Programmable switching frequency from 400kHz to
1.8MHz
High efficiency up to 90%
Low (<40μA) shutdown current over temperature
Over temperature protection
Programmable over-voltage protection
−40°C
to
+125°C
junction temperature range
Available in 24-pin 4mm x 4mm MLF® package
Applications
•
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White LED driver for backlighting
Notebooks
LCD Panels and Monitors
Multimedia players
Navigation equipment
Gaming systems
Video poker
Slot machines
_________________________________________________________________________________________________________________________
MLF is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
January 2010
M9999-012110
Micrel, Inc.
MIC3263
Typical Application
MIC3263 Typical Application Schematic
January 2010
2
M9999-012110
Micrel, Inc.
MIC3263
Ordering Information
Part Number
MIC3263YML
Note:
1. Other Voltage available. Contact Micrel for detail
Junction Temperature Range
(1)
–40° to +125°C
Package
24-Pin 4mm x 4mm MLF®
Lead Finish
Pb-Free
Pin Configuration
24-Pin 4mm x 4mm MLF®
Pin Description
Pin Number
1
2
3
4
5
Pin Name
FSW
RSLP
OVPS
OVP
MODE
Pin Function
Booster Switching Frequency:
Connect a resistor-to-GND to set the switching frequency from 400kHz to 1.8MHz.
Slope Compensation Adjustment Resistor.
OVP and FB voltage divider virtual ground.
Overvoltage Protection Input. This is also the FB voltage for the error amp in the Boost stage.
Select a dimming frequency range:
0V for 100Hz to 2kHz and V
DD
for 1.5kHz to 20kHz. If DFS is connected to V
DD
, MODE pin is
used for an external dimming pulse input.
6
DFS
Set a dimming frequency from 100Hz to 20kHz through an external resistor and MODE.
Requires a series RC for stability.
If DFS is connected to V
DD
, an external dimming pulse can be applied to the MODE pin.
7
8
COMP
DRC
Loop Compensation connect R and C-to-GND.
Dimming Ratio Control Pulse:
Its duty cycle is converted to one of 16 dimming levels. The duty-cycle difference between two
adjacent levels is ±6.25%. And about 2% duty-cycle hysteresis exists between two adjacent
levels to eliminate dimming flicker.
DRC can be from 100Hz to 40kHz.
9
CINT
Integration Cap:
Use a 0.01µF for 2kHz to 20kHz and 0.1µF for 100Hz
─
2kHz.
January 2010
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M9999-012110
Micrel, Inc.
MIC3263
Pin Description (Continued)
Pin Number
10
Pin Name
ISET
Pin Function
LED Dimming Current Set:
Connect a resistor-to-GND to set the dimming current from 15mA to 30mA. Use 2kΩ for 30mA,
and 3kΩ for 20mA.
11
12
13, 14, 15, 16,
17, 18
19
20
21
22
23
24
CRV
AGND
IO1
─
IO6
NC
PGND
VSW
EN
VIN
VDD
EP
Capacitor reference voltage: Connect a 2.2µF capacitor-to-GND.
Analog signal Ground.
LED Channel Current Sinker:
Connect the cathode of each channel of LEDs to one current sinker.
No Connect.
Power Ground.
Switch Node: Internal power NPN collector.
Enable Pin: Connect HIGH or LOW; do not float.
Supply: 6V to 40V.
Output of internal LDO:
Connect a 10µF capacitor-to-GND.
Connect to PGND
January 2010
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M9999-012110
Micrel, Inc.
MIC3263
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
), Enable (V
EN
)...............................+42V
Switch Voltage (V
SW
).....................................
−0
.3V to
+42V
Regulated Voltage (V
DD
) .................................
−
0.3V to
+
6V
Over-Voltage Protection (V
OVP
) ....................
−0
.3V to
+42V
Switch Voltage (V
OVPS
) .................................
−0
.3V to
+42V
DFS Voltage (V
DFS
) ............................
−0.3V
to (V
DD
+ 0.3V)
RSLP (V
RSLP
) ......................................
−
0.3V to (V
DD
+ 0.3V)
MODE Voltage (V
MODE
) ......................
−0.3V
to (V
DD
+ 0.3V)
FSW Voltage (V
FSW
) ...........................
−0.3V
to (V
DD
+ 0.3V)
DRC Voltage (V
DRC
) ...........................
−0.3V
to (V
DD
+ 0.3V)
CRV Voltage (V
CRV
)............................
−
0.3V to (V
DD
+ 0.3V)
CINT Voltage (V
CINT
) ..........................
−0.3V
to (V
DD
+ 0.3V)
ISET Voltage (V
ISET
) ...........................
−0.3V
to (V
DD
+ 0.3V)
Comp Voltage (V
COMP
)........................
−0.3V
to (V
DD
+ 0.3V)
IO1–IO6 Voltage (V
IO1-IO6
) .............................
−0.3V
to
+42V
AGND to PGND ...........................................
−0.3V
to
+0.3V
Lead Temperature (soldering, 10
─
20s) ................... 260°C
Storage Temperature (T
S
).........................
−
65°C to
+150°C
ESD Rating
(3)
............................................................... 1.5kV
Operating Ratings
(2)
Supply Voltage (V
IN
).........................................
+6V
to
+40V
Enable (V
EN
) ..........................................................0 to
+40V
MODE (V
MODE
)......................................................0 to
+5.5V
DFS (V
DFS
)............................................................ 0 to
+5.5V
DRC (V
DRC
)...........................................................0 to
+5.5V
Junction Temperature (T
J
) ........................
−40°C
to
+125°C
Junction Thermal Resistance
24-Pin MLF® (θ
JA
) .............................................43°C/W
Electrical Characteristics
(4)
V
IN
= 12V; L = 22μH, C
OUT
=10μF,T
A
= 25°C,
BOLD
values indicate –40°C≤ T
J
≤
+125°C, unless noted.
Symbol
V
IN
V
IN
I
VIN
V
DDREG
I
SD
IO1
─
IO6
V
OS
Parameter
Supply Voltage Range
Supply Voltage Range
Quiescent Current
VDD Regulation
Shutdown Current (DC Pin Low)
Minimum IO (1–6) Voltage for
operation to Sink 30mA
Maximum Output Voltage
Overshoot when Current
Sources are OFF in PWM Dim
Mode
Channel Current Matching
Initial Current Setting Accuracy
PWM Dimming Frequency
Adjust Range
Condition
30mA 8 LEDs/Channel, All six Channels
30mA 6 LEDs/Channel, All six Channels
Not Switching, V
OVP
= 4V
V
IN
= 6V to 40V, I
DD
= 0mA to 6mA
V
EN
= 0V
Voltage on IO (1–6) if Only One Channel is Used
and I
SET
= 30mA
22μH, 10μF
4.5
Min
8
6
6.5
5
6.5
1.2
3
Typ
Max
40
40
10
5.5
20
μA
V
%
Units
V
V
mA
Current Control
I
LEDMATCH
I
LEDSET
F
DIMR
I
LED
= 30mA and Dimming Ratio = 100%
V
IO
= 1.2V on All Channels
R
SET
= 2k
I
LED
= 30mA
MODE = 0V, R
DFS
= 400kΩ, Frequency = 100Hz
MODE = 0V, R
DFS
= 32kΩ, Frequency = 1.2kHz
MODE = V
DD
, R
DFS
= 400kΩ, Frequency = 1.6kHz
MODE = V
DD
, R
DFS
= 32kΩ, Frequency = 20kHz
−3
−2
−3
0.1
0
0
+3
+2
+3
20
%
%
kHz
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
January 2010
5
M9999-012110
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