Microchip MIC4812 Handleiding


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MIC4812
High Current 6 Channel Linear WLED
Driver with DAMâ„¢ and Ultra Fast
PWMâ„¢ Control
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
General Description
The MIC4812 is a high efficiency linear White LED
(WLED) driver designed to drive up to six high current
WLEDs for signage lighting. The MIC4812 provides the
highest possible efficiency as this architecture has no
switching losses present in traditional charge pumps or
inductive boost circuits. The MIC4812 provides six linear
drivers which maintain constant current for up to six
WLEDs. It features a typical dropout of 190mV at 100mA.
The MIC4812 features Dynamic Average Matchingâ„¢
(DAMâ„¢) 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 PWMâ„¢ interface
operating down to less than 1% duty cycle.
The MIC4812 is available in an 10-pin MSOP ePad
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 100mA per channel
• Programmable LED current with external resistor
• Dropout of 190mV at 100mA
• Matching better than ±1% (typical)
• Current Accuracy better than ±1% (typical)
• Maintains proper regulation regardless of how many
channels are utilized
• 10-pin MSOP with ePad package
Applications
• Billboard displays
• Marquee displays
• Instrument displays
• LCD display modules
____________________________________________________________________________________________________________
Typical Application
High Current Lighting (Six WLEDs)
April 2011 M9999-041911-B
Micrel Inc. MIC4812
April 2011 2 M9999-041419-B
Ordering Information
Part Number Mark Code Junction Temperature Range Package
MIC4812YMME 4812 –40°C to +125°C 10-Pin ePad MSOP
Pin Configuration
10-Pin ePad MSOP (MME)
(Top View)
Pin Description
Pin Number Pin Name Pin Function
1 VIN Voltage Input. Connect at least 2.2µF ceramic capacitor between VIN and GND.
2 EN Enable LED drivers. This pin can be used as a PWM input for dimming of WLEDs. Do not leave
floating.
3 RSET An internal 1.27V reference sets the nominal maximum WLED current. Example, apply a 8.25kΩ
resistor between RSET and GND to set LED current to 100mA at 100% duty cycle.
4 GND Ground.
5 D6 LED6 driver input. Connect LED anode to VIN and cathode to this pin.
6 D5 LED5 driver input. Connect LED anode to VIN and cathode to this pin.
7 D4 LED4 driver input. Connect LED anode to VIN and cathode to this pin.
8 D3 LED3 driver input. Connect LED anode to VIN and cathode to this pin.
9 D2 LED2 driver input. Connect LED anode to VIN and cathode to this pin.
10 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin.
ePad HS PAD Heat sink pad. Not internally connected. Connect to ground.
Micrel Inc. MIC4812
April 2011 3 M9999-041419-B
Absolute Maximum Ratings(1)
Main Input Voltage (VIN) .................................. –0.3V to +6V
Enable Input Voltage (VEN).............................. –0.3V to +6V
LED Driver Voltage (VD1-D6) ............................ –0.3V to +6V
Power Dissipation .....................................Internally Limited
Lead Temperature (soldering, 10sec.)....................... 260°C
Storage Temperature (Ts) .........................–65°C to +150°C
ESD Rating(3)............................................................... 1.5kV
Operating Ratings(2)
Supply Voltage (VIN)..................................... +3.0V to +5.5V
Enable Input Voltage (VEN) .................................... 0V to V
IN
LED Driver Voltage (VD1-D6) ................................... 0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Junction Thermal Resistance
ePad MSOP-10L (θJA
) ....................................76.7°C/W
Electrical Characteristics
VIN = VEN = 5V, RSET = 8.25kΩ; VD1-D6 = 1.2V; TJ = 25° °C, bold values indicate –40 C ≤ T J ≤ 125°C; unless noted.
Parameter Conditions Min Typ Max Units
Current Accuracy(4) 96 101 106 mA
Matching(5) 1 3.6 %
Drop-out Where ILED = 90% of LED current seen at
VDROPNOM = 1.2V, 100% brightness level 190 320 mV
Ground/Supply Bias Current 3.2 4.2 mA
Shutdown Current VEN = 0V 0.01 1 µA
PWM Dimming
Logic Low 0.2 V Enable Input Voltage (V
EN)
Logic High 1.2 V
Enable Input Current VIH > 1.2V 0.01 1 µA
Current Source Delay
(50% levels)
Shutdown to on
Standby to on
On to Standby
40
1
0.3
60 µs
µs
µs
Current Source Transient Time
(10%-90%)
TRISE
TFALL
1
0.3
µs
µs
Stand-by to Shutdown Time VEN = 0V 10 20 40 ms
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.


Product specificaties

Merk: Microchip
Categorie: Niet gecategoriseerd
Model: MIC4812

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