Microchip MIC4802 Bedienungsanleitung


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MIC4802
High Efficiency 800mA Single Channel
Linear WLED Driver with
Ultra Fast PWMâ„¢ Control
Ultra Fast PWM is a 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 2011 M9999-013111-B
General Description
The MIC4802 is a high efficiency White LED (WLED)
driver designed to drive a single LED up to 800mA. The
MIC4802 constant current driver is designed to drive high
power LED’s in various lighting applications. The MIC4802
provides the highest possible efficiency as this architecture
has no switching losses present in traditional charge
pumps or inductive boost circuits. It features a typical
dropout of 280mV at 800mA. This allows the LEDs to be
driven directly from the voltage source eliminating
switching noise/losses present with the use of boost
circuitry. The high accuracy (±1% Typical) current
regulated WLED channel ensures uniform display
illumination under all conditions. The brightness is
controlled through an Ultra Fast PWMâ„¢ Control interface
operating down to less than 1% duty cycle.
The MIC4802 is available in the 8-pin SOIC 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
• Dropout of 280mV at 800mA
• Programmable LED current with external resistor
• Current accuracy of ±1% typical
Applications
• Bill board displays
• Marquee displays
• Instrument displays
• Architectural lighting
____________________________________________________________________________________________________________
Typical Application
High Current Lighting Schematic
Micrel Inc. MIC4802
January 2011 2 M9999-013111-B
Ordering Information
Part Number Temperature Range Package
MIC4802YME –40°C to +125°C 8-Pin EPAD SOIC
Pin Configuration
8-Pin Epad SOIC (ME)
(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 6.19kΩ
resistor between RSET and GND to set LED current to 830mA at 100% duty cycle.
4 GND Ground.
5 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
6 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
7 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
8 D1 LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
EPAD HS PAD Heat sink pad. Not internally connected. Connect to ground.
Micrel Inc. MIC4802
January 2011 3 M9999-013111-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) ................................ –0.3V to +6V
Power Dissipation .....................................Internally Limited
Lead Temperature (soldering, 10sec.)....................... 260°C
Storage Temperature (Ts) .........................–65°C to +150°C
Operating Ratings(2)
Supply Voltage (VIN)..................................... +3.0V to +5.5V
Enable Input Voltage (VEN) .................................... 0V to V
IN
LED Driver Voltage (VD1) ....................................... 0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Junction Thermal Resistance
EPAD SOIC-8L (θJA)..........................................41°C/W
Electrical Characteristics
VIN = VEN = 5V, RSET = 6.19kΩ; VD1 = 1.2V; TJ = 25° °C, bold values indicate –40 C ≤ TJ ≤ 125°C; unless noted.
Parameter Conditions Min Typ Max Units
Current Accuracy(3) 747 830 913 mA
Drop-out Where ILED = 90% of LED current seen at
VDROPNOM = 1.2V, 100% brightness level 280 500 mV
Ground/Supply Bias Current IOUT = 830mA 4.1 5.7 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
2
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. As determined by average current based on R
SET resistance.


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Marke: Microchip
Kategorie: Nicht kategorisiert
Modell: MIC4802

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