MIC4801
High Efficiency 600mA Single Channel
Linear WLED Driver with
Ultra Fast PWM™ Control
General Description
The MIC4801 is a high efficiency White LED (WLED)
driver designed to drive a single LED up to 600mA. The
MIC4801 constant current driver is designed to drive high
power LED’s in various lighting applications. The MIC4801
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 130mV at 400mA. 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 PWM™ Control interface operating down to less than
1% duty cycle.
The MIC4801 is available in an 8-pin SOIC 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 130mV at 400mA
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
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
M9999-011811-A
Micrel Inc.
MIC4801
Ordering Information
Part Number
MIC4801YM
Temperature Range
–40°C to +125°C
Package
8-Pin SOIC
Pin Configuration
8-Pin SOIC (M)
(Top View)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
Pin Name
VIN
EN
RSET
GND
D1
D1
D1
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 12.1kΩ
resistor between RSET and GND to set LED current to 416mA at 100% duty cycle.
Ground.
LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
LED1 driver input. Connect LED anode to VIN and cathode to this pin. All D1 pins must be
connected to the LED.
January 2011
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M9999-011811-A
Micrel Inc.
MIC4801
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
) ................................ –0.3V to +6V
Power Dissipation .....................................Internally Limited
Lead Temperature (soldering, 10sec.)....................... 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
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
) ....................................... 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
SOIC-8L (θ
JA
)..................................................98.9°C/W
Electrical Characteristics
V
IN
= V
EN
= 5V, R
SET
= 12.1kΩ; V
D1
= 1.2V; T
J
= 25°C,
bold
values indicate –40°C
≤
T
J
≤
125°C; unless noted.
Parameter
Current Accuracy
(3)
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. As determined by average current based on R
SET
resistance.
Conditions
Where I
LED
= 90% of LED current seen at
V
DROPNOM
= 1.2V, 100% brightness level
I
OUT
= 416mA
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
Min
374
Typ
416
130
2.2
0.01
Max
458
250
2.9
1
0.2
Units
mA
mV
mA
µA
V
V
µA
µs
µs
µs
µs
µs
1.2
0.01
40
2
0.3
1
0.3
10
20
40
1
60
ms
January 2011
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Micrel Inc.
MIC4801
Typical Characteristics
1
0.9
0.8
LED CURRENT (A)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
5.5
5
4.5
4
3.5
3
2.5
LED ANODE VOLTAGE (V)
LED Current
vs. LED Anode Voltage
VIN = 5.5V
DROPOUT VOLTAGE (mV)
300
275
250
225
200
175
150
125
100
75
50
25
0
0
Dropout Voltage
vs. LED Current
6
5.5
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
5.5
Supply Bias Current
vs. LED Anode Voltage
VIN = 3.0V
VIN = 5.5V
VIN = 3.5V
VIN = 3.0V
Supply Bias Current (mA)
VIN = 2.5V
VIN = 5V
100 200 300 400 500 600 700 800
LED CURRENT (mA)
R
SET
= 4.64kΩ
5
4.5
4
3.5
3
2.5
LED ANODE VOLTAGE (V)
1000
Peak LED Current
vs. R
SET
LED Current
vs. PWM Duty Cycle
900
800
LED CURRENT (mA)
700
600
500
400
300
200
100
f
PWM
= 10kHz
f
PWM
= 5kHz
VIN = 5V
LED Current
vs. PWM Duty Cycle
900
800
LED CURRENT (mA)
700
600
500
400
300
200
100
0
f
PWM
= 500kHz
0
20
40
60
80
100
f
PWM
= 200kHz
f
PWM
= 100kHz
f
PWM
= 20kHz
f
PWM
= 1kHz
ILED (mA)
100
10
1
1
10
100
RSET (kΩ)
1000
10000
0
0
20
40
60
80
100
DUTY CYCLE (%)
DUTY CYCLE (%)
RSET Voltage
vs. LED Current
1.34
1.33
RSET VOLTAGE (V)
LED CURRENT (A)
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
Typical I
LED
vs. V
LED
VIN = 5.0V
1.32
1.31
1.3
1.29
1.28
1.27
1.26
1.25
0
100 200 300 400 500 600 700 800
LED CURRENT (mA)
VIN = 5V
0.2
0
2.4
2.6
2.8
3
3.2
3.4
3.6
LED FORWARD VOLTAGE (V)
January 2011
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M9999-011811-A
Micrel Inc.
MIC4801
Functional Characteristics
January 2011
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M9999-011811-A
PCB设计
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