MIC4811
High Current 6 Channel Linear WLED
Driver with DAM™ and Ultra Fast
PWM™ Control
General Description
The MIC4811 is a high efficiency linear White LED
(WLED) driver designed to drive up to six high current
WLEDs for signage lighting. The MIC4811 provides the
highest possible efficiency as this architecture has no
switching losses present in traditional charge pumps or
inductive boost circuits. The MIC4811 provides six linear
drivers which maintain constant current for up to six
WLEDs. It features a typical dropout of 100mV at 50mA.
The MIC4811 features Dynamic Average Matching™
(DAM™) which is specifically designed to provide optimum
matching across all WLEDs. The high accuracy (±1%
typical) current regulated WLED channels ensure uniform
display illumination under all conditions. The brightness is
controlled through an Ultra Fast PWM™ interface
operating down to less than 1% duty cycle.
The MIC4811 is available in an 10-pin MSOP package
with a junction temperature range of -40°C to +125°C.
Datasheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com.
Features
•
•
•
•
•
•
•
•
•
High Efficiency (no Voltage Boost losses)
Ultra Fast PWM™ control (200Hz to 500kHz)
Input voltage range: 3.0V to 5.5V
LED current range up to 50mA per channel
Programmable LED current with external resistor
Dropout of 100mV at 50mA
Matching better than ±1% (typical)
Current Accuracy better than ±1% (typical)
Maintains proper regulation regardless of how many
channels are utilized
•
10-pin MSOP package
Applications
•
Billboard displays
•
Marquee displays
•
Instrument displays
•
LCD display modules
____________________________________________________________________________________________________________
Typical Application
High Current Lighting (Six WLEDs)
Ultra Fast PWM, DAM and Dynamic Average Matching are 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
April 2011
M9999-041411-B
Micrel Inc.
MIC4811
Ordering Information
Part Number
MIC4811YMM
Mark Code
(1)
4811
Junction Temperature Range
–40°C to +125°C
Package
10-Pin MSOP
Pin Configuration
10-Pin MSOP (MM)
(Top View)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
Pin Name
VIN
EN
RSET
GND
D6
D5
D4
D3
D2
D1
Pin Function
Voltage Input. Connect at least 2.2µF ceramic capacitor between VIN and GND.
Enable LED drivers. This pin can be used as a PWM input for dimming of WLEDs. Do not leave
floating.
An internal 1.27V reference sets the nominal maximum WLED current. Example, apply a 16.5kΩ
resistor between RSET and GND to set LED current to 50mA at 100% duty cycle.
Ground.
LED6 driver input. Connect LED anode to VIN and cathode to this pin.
LED5 driver input. Connect LED anode to VIN and cathode to this pin.
LED4 driver input. Connect LED anode to VIN and cathode to this pin.
LED3 driver input. Connect LED anode to VIN and cathode to this pin.
LED2 driver input. Connect LED anode to VIN and cathode to this pin.
LED1 driver input. Connect LED anode to VIN and cathode to this pin.
April 2011
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M9999-041411-B
Micrel Inc.
MIC4811
Absolute Maximum Ratings
(1)
Main Input Voltage (V
IN
) .................................. –0.3V to +6V
Enable Input Voltage (V
EN
).............................. –0.3V to +6V
LED Driver Voltage (V
D1-D6
) ............................ –0.3V to +6V
Power Dissipation .....................................Internally Limited
Lead Temperature (soldering, 10sec.)....................... 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
ESD Rating
(3)
............................................................... 1.5kV
Operating Ratings
(2)
Supply Voltage (V
IN
)..................................... +3.0V to +5.5V
Enable Input Voltage (V
EN
) .................................... 0V to V
IN
LED Driver Voltage (V
D1-D6
) ................................... 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
MSOP-10L (θ
JA
) ............................................130.5°C/W
Electrical Characteristics
V
IN
= V
EN
= 5V, R
SET
= 16.5kΩ; V
D1-D6
= 1.2V; T
J
= 25°C,
bold
values indicate –40°C
≤
T
J
≤
125°C; unless noted.
Parameter
Current Accuracy
(4)
Matching
(5)
Drop-out
Ground/Supply Bias Current
Shutdown Current
PWM Dimming
Enable Input Voltage (V
EN
)
Enable Input Current
Current Source Delay
(50% levels)
Current Source Transient Time
(10%-90%)
Stand-by to Shutdown Time
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, 1.5kΩ in series with 100pF.
4. As determined by average current of all channels in use and all channels loaded.
5. The current through each LED meets the stated limits from the average current of all LEDs.
Conditions
Min
47.5
Typ
50
1
Max
52.5
3.6
180
2.2
1
0.2
Units
mA
%
mV
mA
µA
V
V
µA
µs
µs
µs
µs
µs
Where I
LED
= 90% of LED current seen at
V
DROPNOM
= 1.2V, 100% brightness level
V
EN
= 0V
Logic Low
Logic High
V
IH
> 1.2V
Shutdown to on
Standby to on
On to Standby
T
RISE
T
FALL
V
EN
= 0V
10
1.2
100
1.7
0.01
0.01
40
1
0.3
1
0.3
20
1
60
40
ms
April 2011
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Micrel Inc.
MIC4811
Typical Characteristics
100
AVERAGE CURRENT (mA)
90
80
Average Current
vs. Duty Cycle
1000
Single Channel Current
vs. R
SET
DROPOUT VOLTAGE (mV)
900
800
700
600
500
400
300
200
100
0
0
Single Channel Dropout
vs. LED Current
CURRENT (mA)
70
60
50
40
30
20
10
0
0
20
40
60
80
100
DUTY CYCLE (% )
100
10
1
1
10
100
1000
RSET (kΩ)
100
200
300
400
500
LED CURRENT (mA)
140
DROPOUT VOLTAG (mV)
120
100
80
60
40
20
0
-40 -20
Dropout Voltage
vs. Temperature
CURRENT MATCHING (%)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Average Current Matching
vs. Temperature
52.0
51.5
LED CURRENT (mA)
51.0
50.5
50.0
49.5
49.0
48.5
48.0
-40 -20
LED6
LED Current
vs. Temperature
LED5
LED4
LED1
LED2
LED3
R
SET
= 16.5kΩ
R
SET
= 16.5kΩ
0
20 40
60 80 100 120 140
-40 -20
0
20
40 60
80 100 120 140
0
20
40
60
80 100 120 140
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
51.0
50.5
PEAK ILED (mA)
LED2
Peak ILED
vs. Input Voltage
50.0
49.5
LED6
LED5
LED3
49.0
48.5
LED4
LED1
R
SET
= 16.5kΩ
48.0
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
April 2011
4
M9999-041411-B
Micrel Inc.
MIC4811
Functional Characteristics
April 2011
5
M9999-041411-B
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