MIC2843
High-Efficiency 6-Channel
Linear WLED Driver with
Ultra-Fast PWM™ Control
General Description
The MIC2843 is a high-efficiency linear white LED (WLED)
driver designed to drive up to six WLEDs, greatly
extending battery life for portable display backlighting,
keypad backlighting, and camera flash in mobile devices.
The MIC2843 provides the highest possible efficiency as
this architecture has no switching losses present in
traditional charge pumps or inductive boost circuits. The
MIC2843 provides six linear drivers which maintain
constant current for up to six WLEDs. It features a typical
dropout of less than 40mV at 20mA. This allows the
WLEDs to be driven directly from the battery eliminating
switching noise/losses present with the use of boost
circuitry.
The six channels are matched better than ±3% typical,
ensuring 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 MIC2843 is available in the 2mm x 2mm 10-pin Thin
®
MLF leadless 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
Dropout of less than 40mV at 20mA
Matching better than ±3% (typical)
Current accuracy better than ±1.5% (typical)
Maintains proper regulation regardless of how many
channels are utilized
•
Available in a 2mm x 2mm 10-pin Thin MLF
®
package
Applications
•
Mobile handsets
•
Digital cameras
•
Portable media/MP3 players
•
Portable navigation devices (GPS)
•
Portable applications
____________________________________________________________________________________________________________
Typical Application
LCD Display Backlight with Six WLEDs
Ultra Fast PWM is a trademark of Micrel, Inc.
MLF and
MicroLeadFrame
are registered trademark Amkor Technology Inc.
High Current Flash Driver
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
November 2010
M9999-110810-B
Micrel Inc.
MIC2843
Ordering Information
Part Number
MIC2843YMT
Note:
1.
2.
Thin MLF
▲
= Pin 1 identifier.
Thin MLF is a GREEN RoHS-compliant package. Lead finish is NiPdAu. Mold compound is halogen free.
®
®
Mark Code
(1)
YS3
Temperature Range
–40°C to +125°C
Package
(2)
10-Pin 2mm x 2mm Thin MLF
®
Pin Configuration
10-Pin 2mm x 2mm Thin MLF
®
(MT)
(Top View)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
EPAD
Pin Name
VIN
END
R
SET
GND
D6
D5
D4
D3
D2
D1
HS PAD
Pin Function
Voltage Input. Connect at least 1µF ceramic capacitor between V
IN
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 20.5kΩ
resistor between R
SET
and GND to set LED current to 20mA 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.
Heat sink pad. Not internally connected. Connect to ground.
November 2010
2
M9999-110810-B
Micrel Inc.
MIC2843
Absolute Maximum Ratings
(1)
Main Input Voltage (V
IN
) ..................................
−0.3V
to +6V
Enable Input Voltage (V
END
) ............................
−0.3V
to +6V
Current Source 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)
................................................. ESD Sensitive
Operating Ratings
(2)
Supply Voltage (V
IN
)..................................... +3.0V to +5.5V
Enable Input Voltage (V
END
) .................................. 0V to V
IN
Current Source Voltage (V
D1-D6
) ............................ 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
2mm x 2mm Thin MLF
®
-10L (θ
JA
)......................90°C/W
Electrical Characteristics
WLED Linear Drivers
V
IN
= V
END
= 3.8V, R
SET
= 20.5kΩ; V
D1-D6
= 0.6V; 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
(Current Source Leakage)
PWM Dimming
Enable Input Voltage (V
END
)
Enable Input Current
Current Source Delay
(50% levels)
Current Source Transient Time
(10%
−
90%)
Standby to Shutdown Time
Notes:
1.
2.
3.
4.
5.
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
As determined by average current of all channels in use and all channels loaded.
The current through each LED meets the stated limits from the average current of all LEDs.
Conditions
V
DROPNOM
= 0.6V
V
DROPNOM
= 0.6V
Where I
LED
= 90% of LED current seen at
V
DROPNOM
= 0.6V, 100% brightness level
I
OUT
= 20mA
V
END
= 0V
Min.
Typ.
1.5
3
40
1.4
0.01
Max.
5.5
100
Units
%
%
mV
mA
1
µA
Logic Low
Logic High
V
IH
> 1.2V
Shutdown to On
Standby to On
On to Standby
R
SET
= 20.5k
T
RISE
T
FALL
V
END
= 0V
10
1
0.3
20
1.2
0.01
40
0.5
1
0.2
1
V
V
µA
µs
µs
µs
µs
µs
60
40
ms
November 2010
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M9999-110810-B
Micrel Inc.
MIC2843
Typical Characteristics
November 2010
4
M9999-110810-B
Micrel Inc.
MIC2843
Typical Characteristics (Continued)
November 2010
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M9999-110810-B
微控制器 MCU
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