MIC2289-15BML [MICROCHIP]
LED Driver, 3-Segment, 2 X 2 MM, MLF-8;
| 型号： | MIC2289-15BML |
| 厂家： | 
MICROCHIP |
| 描述： | LED Driver, 3-Segment, 2 X 2 MM, MLF-8 驱动 接口集成电路 |
| 文件： | 总10页 (文件大小：267K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2289
White LED Driver Internal Schottky
Diode and OVP
General Description
Features
The MIC2289 is a PWM (pulse width modulated), boost-
switching regulator that is optimized for constant-current
white LED driver applications. The MIC2289 features an
internal Schottky diode and three levels of output
overvoltage protection providing a small size and efficient
DC/DC solution that requires only four external
components.
• 2.5V to 10V input voltage
• Output voltage up to 34V
• Internal Schottky diode
• 15V, 24V, 34V output OVP options
• 1.2 MHz PWM operation
• Over 500mA switch current
• 95mV feedback voltage
To optimize efficiency, the feedback voltage is set to only
95mV. This reduces power dissipation in the current set
resistor and allows the lowest total output voltage, hence
minimal current draw from the battery.
• <1% line and load regulation
• <1µA shutdown current
• Overtemperature protection
• UVLO
The MIC2289 implements a constant frequency 1.2MHz
PWM control scheme. The high frequency, PWM operation
saves board space by reducing external component sizes.
The added benefit of the constant frequency PWM scheme
in caparison to variable frequency is much lower noise and
input ripple injected to the input power source.
• 2mm × 2mm 8-pin MLF® package
• –40°C to +125°C junction temperature range
Applications
The MIC2289 clamps the output voltage in case of open
LED conditions, protecting itself and the output capacitor.
The MIC2289 is available with three output OVP options of
15V, 24V, and 34V. The different OVP options allows the
use of the smallest possible output capacitor with the
appropriate voltage rating for a given application.
• White LED driver for backlighting:
– Cell phones
– PDAs
– GPS systems
– Digital cameras
– MP3 players
– IP phones
The MIC2289 is available in low profile 6-pin Thin SOT-23
and 8-pin 2mm × 2mm MLF® package options. The
MIC2289 has a junction temperature range of –40°C to
+125°C.
• LED flashlights
• Constant current power supplies
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Typical Application
10µH
3-Series LED Efficiency
82
80
78
76
74
MIC2289-15BML
VIN
SW
1-Cell
Li Ion
1µF
0.22µF/16V
OUT
FB
95mV
EN
GND
72
VIN =3.6V
15 20 25
70
0
5
10
IOUT (mA)
3-Series White LED Driver
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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
M9999-071007
July 2007
Micrel, Inc.
MIC2289
Ordering Information
Marking
Overvoltage
Protection
Junction
Temp. Range
Part Number
Code
SM24
SNA
SNA
SNB
SNB
SNC
SNC
Package
Lead Finish
MIC2289-24YD6
MIC2289-15BML
MIC2289-15YML
MIC2289-24BML
MIC2289-24YML
MIC2289-34BML
MIC2289-34YML
24V
15V
15V
24V
24V
34V
34V
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
6-Pin Thin SOT-23
Pb-Free
Standard
Pb-Free
Standard
Pb-Free
Standard
Pb-Free
8-Pin 2mm x 2mm MLF®
8-Pin 2mm x 2mm MLF®
8-Pin 2mm x 2mm MLF®
8-Pin 2mm x 2mm MLF®
8-Pin 2mm x 2mm MLF®
8-Pin 2mm x 2mm MLF®
Note: Marking bars may not be to scale.
Pin Configuration
GND
2
FB
3
SW
1
VOUT
1
2
3
4
8
7
6
5
PGND
SW
VIN
EN
FB
AGND
EP
NC
4
5
6
EN VIN VOUT
6- Pin Thin SOT-23 (D6)
8-Pin MLF® (ML)
(Top View)
Fused Lead Frame
Pin Description
Pin Number
TSOT-23-6
Pin Number
MLF® -8
Pin Name
SW
Pin Name
1
2
3
7
―
6
Switch node (Input): Internal power BIPOLAR collector.
Ground (Return): Ground.
GND
FB
Feedback (Input): Output voltage sense node. Connect the
cathode of the LED to this pin. A resistor from this pin to ground
sets the LED current.
4
3
EN
Enable (Input): Logic high enables regulator. Logic low shuts
down regulator.
5
6
2
1
VIN
Supply (Input): 2.7V to 8V for internal circuitry.
VOUT
Output Pin and Overvoltage Protection (Output): Connect to the
output capacitor and LEDs.
―
―
―
―
4
8
AGND
PGND
NC
Analog ground.
Power ground.
5
No connect (no internal connection to die).
Ground (Return): Exposed backside pad.
EP
GND
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July 2007
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Micrel, Inc.
MIC2289
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN).......................................................12V
Switch Voltage (VSW)....................................... –0.3V to 34V
Enable Pin Voltage (VEN)...................................–0.3V to VIN
FB Voltage (VFB)...............................................................6V
Switch Current (ISW) .........................................................2A
Ambient Storage Temperature (Ts)...........–65°C to +150°C
Schottky Reverse Voltage (VDA).....................................34V
EDS Rating(3)..................................................................2kV
Supply voltage (VIN) ........................................ 2.5V to +10V
Output Voltage (VIN)............................................ VIN to VOVP
Junction Temperature (TJ) ........................–40°C to +125°C
Package Thermal Resistance
2mm x 2mm MLF® (θJA).....................................93°C/W
Thin SOT-23-6 (θJA) ........................................177°C/W
Electrical Characteristics(4)
TA = 25°C, VIN = VEN = 3.6V, VOUT = 10V, IOUT = 20mA, unless otherwise noted. Bold values indicate –40°C< TJ < +125°C.
Symbol
VIN
Parameter
Condition
Min
2.5
1.8
Typ
Max
10
2.4
5
Units
V
Supply Voltage Range
Under Voltage Lockout
Quiescent Current
Shutdown Current
Feedback Voltage
Feedback Input Current
Line Regulation(6)
Load Regulation(6)
Maximum Duty Cycle
Switch Current Limit
Switch Saturation Voltage
Switch Leakage Current
Enable Threshold
VUVLO
IVIN
2.1
2.5
V
VFB > 200mV, (not switching)
mA
µA
mV
nA
%
ISD
V
EN = 0V(5)
0.1
1
VFB
(±5%)
90
95
100
IFB
VFB = 95mV
3V ≤ VIN ≤ 5V
5mA ≤ IOUT ≤ 20mA
–450
0.5
1
0.5
%
DMAX
ISW
85
90
%
750
450
0.01
mA
mV
µA
VSW
ISW
ISW = 0.5A
VEN = 0V, VSW = 10V
5
VEN
TURN ON
TURN OFF
1.5
V
V
0.4
40
1.35
1
IEN
Enable Pin Current
VEN = 10V
20
1.2
0.8
µA
MHz
V
fSW
VD
Oscillator Frequency
Schottky Forward Drop
Schottky Leakage Current
Overvoltage Protection
1.05
ID = 150mA
VR = 30V
IRD
4
µA
VOVP
MIC2289-15
MIC2289-24
MIC2289-34
13
21
30
14
22.5
32
16
24
34
V
V
V
TJ
Overtemperature
Threshold Shutdown
150
10
°C
°C
Hysteresis
Notes:
1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating
the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max), the
junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive die
temperature, and the regulator will go into thermal shutdown.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model.
4. Specification for packaged product only.
5. ISD = IVIN
.
6. Guaranteed by design
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July 2007
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Micrel, Inc.
MIC2289
Typical Characteristics
Shutdown Voltage
vs. Input Voltage
Quiescent Current
vs. Input Current
Feedback Voltage
vs. Input Voltage
100
5
4
3
2
1
0
5
4
3
2
1
0
99
98
97
96
95
94
93
92
91
90
0
2
4
6
8
10 12
0
2
4
6
8
10 12
0
2
4
6
8
10 12
VIN (V)
VIN (V)
VIN (V)
Schottky Forward
Voltage Drop
EN Pin Bias Current
vs. Temperature
Switch Frequency
vs. Temperature
700
600
500
400
300
200
100
0
50
45
40
35
30
25
20
15
10
5
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
IE N = 10V
IE N = 4.2V
IE N = 3.0V
IE N = 3.6V
0
-40 -20
0
20 40 60 80 100
-50
0
50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
SCHOTTKY FORWARD VOLTAGE DROP (mV)
Saturation Voltage
vs. Temperature
Current Limit
vs. Temperature
900
Schottky Reverse
Leakage Current
550
500
450
400
350
300
2.5
2
850
800
750
700
VR = 25V
VR = 16V
VR = 10V
1.5
1
0.5
0
650
VIN = 2.5V
IS W = 500mA
600
30 40 50 60 70 80 90 100
TEMPERATURE (°C)
-40
0
40
80
120
-40
0
40
80
120
TEMPERATURE (°C)
TEMPERATURE (°C)
Switch Saturation Voltage
vs. Current
600
500
400
300
200
100
0
VIN = 2.5V
VIN = 5V
0
100 200 300 400 500
ISW (mA)
M9999-071007
July 2007
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Micrel, Inc.
MIC2289
Functional Diagram
VIN
FB
EN
OUT
OVP
SW
PWM
Generator
gm
VREF
95mV
S
GND
1.2MHz
Ramp
Oscillator
Generator
MIC2289 Block Diagram
The gm error amplifier measures the LED current through
the external sense resistor and amplifies the error
between the detected signal and the 95mV reference
voltage. The output of the gm error amplifier provides the
voltage-loop signal that is fed to the other input of the
PWM generator. When the current-loop signal exceeds
the voltage-loop signal, the PWM generator turns off the
bipolar output transistor. The next clock period initiates
the next switching cycle, maintaining the constant
frequency current-mode PWM control. The LED is set by
the feedback resistor:
Functional Description
The MIC2289 is a constant frequency, PWM current
mode boost regulator. The block diagram is shown
above. The MIC2289 is composed of an oscillator, slope
compensation ramp generator, current amplifier, gm error
amplifier, PWM generator, 500mA bipolar output
transistor, and Schottky rectifier diode. The oscillator
generates a 1.2MHz clock. The clock’s two functions are
to trigger the PWM generator that turns on the output
transistor and to reset the slope compensation ramp
generator. The current amplifier is used to measure the
switch current by amplifying the voltage signal from the
internal sense resistor. The output of the current
amplifier is summed with the output of the slope
compensation ramp generator. This summed current-
loop signal is fed to one of the inputs of the PWM
generator.
95mW
ILED
=
RFB
The Enable pin shuts down the output switching and
disables control circuitry to reduce input current-to-
leakage levels. Enable pin input current is zero at zero
volts.
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July 2007
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Micrel, Inc.
MIC2289
inductor and output capacitor values for various series-
LED applications.
External Component Selection
The MIC2289 can be used across a wide rage of
applications. The table below shows recommended
Series LEDs
L
Manufacturer
Min COUT
Manufacturer
2
22µH
LQH32CN220K21 (Murata)
NLC453232T-220K(TDK)
LQH32CN150K21 (Murata)
NLC453232T-150K(TDK)
LQH32CN100K21 (Murata)
NLC453232T-100K(TDK)
LQH32CN6R8K21 (Murata)
NLC453232T-6R8K(TDK)
LQH32CN4R7K21 (Murata)
NLC453232T-4R7K(TDK)
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
2.2µF
0805ZD225KAT(AVX)
GRM40X5R225K10(Murata)
0805ZD105KAT(AVX)
GRM40X5R105K10(Murata)
0805ZD224KAT(AVX)
GRM40X5R224K10(Murata)
0805ZD225KAT(AVX)
GRM40X5R225K10(Murata)
0805ZD224KAT(AVX)
GRM40X5R224K10(Murata)
0805YD225MAT(AVX)
GRM40X5R225K16(Murata)
0805YD105MAT(AVX)
GRM40X5R105K16(Murata)
0805YD224MAT(AVX)
GRM40X5R224K16(Murata)
0805YD224MAT(AVX)
GRM40X5R224K16(Murata)
0805YD274MAT(AVX)
GRM40X5R224K16(Murata)
0805YD105MAT(AVX)
GRM40X5R105K25(Murata)
0805YD105MAT(AVX)
GRM40X5R105K25(Murata)
0805YD274MAT(AVX)
GRM40X5R274K25(Murata)
0805YD274MAT(AVX)
GRM40X5R274K25(Murata)
0805YD274MAT(AVX)
GRM40X5R274K25(Murata)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
08053D274MAT(AVX)
15µH
10µH
6.8µH
4.7µH
22µH
15µH
10µH
6.8µH
4.7µH
22µH
15µH
10µH
6.8µH
4.7µH
22µH
15µH
10µH
6.8µH
4.7µH
22µH
15µH
10µH
6.8µH
4.7µH
1µF
0.22µF
0.22µF
0.22µF
2.2µF
3
1µF
0.22µF
0.22µF
0.27µF
1µF
4
1µF
0.27µF
0.27µF
0.27µF
0.22µF
0.22µF
0.27µF
0.27µF
0.27µF
0.22µF
0.22µF
0.27µF
0.27µF
0.27µF
5, 6
7, 8
GRM40X5R274K25(Murata)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
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Micrel, Inc.
MIC2289
Dimming Control
Open-Circuit Protection
There are two techniques for dimming control. One is
PWM dimming, and the other is continuous dimming.
If the LEDs are disconnected from the circuit, or in case
an LED fails open, the sense resistor will pull the FB pin
to ground. This will cause the MIC2289 to switch with a
high duty-cycle, resulting in output overvoltage. This may
cause the SW pin voltage to exceed its maximum
voltage rating, possibly damaging the IC and the
external components. To ensure the highest level of
protection, the MIC2289 has 3 product options in the
2mm × 2mm MLF®-8 with overvoltage protection, OVP.
The extra pins of the 2mm × 2mm MLF®-8 package
allow a dedicated OVP monitor with options for 15V,
24V, or 34V (see Figure 3). The reason for the three
OVP levels is to let users choose the suitable level of
OVP for their application. For example, a 3-LED
application would typically see an output voltage of no
more than 12V, so a 15V OVP option would offer a
suitable level of protection. This allows the user to select
the output diode and capacitor with the lowest voltage
ratings, therefore smallest size and lowest cost. The
OVP will clamp the output voltage to within the specified
limits.
1. PWM dimming control is implemented by
applying a PWM signal on EN pin as shown in
Figure 1. The MIC2289 is turned on and off by
the PWM signal. With this method, the LEDs
operate with either zero or full current. The
average LED current is increased proportionally
to the duty-cycle of the PWM signal. This
technique has high-efficiency because the IC
and the LEDs consume no current during the off
cycle of the PWM signal. Typical frequency
should be between 100Hz and 10kHz.
2. Continuous dimming control is implemented by
applying a DC control voltage to the FB pin of
the MIC2289 through a series resistor as shown
in Figure 2. The LED current is decreased
proportionally with the amplitude of the control
voltage. The LED intensity (current) can be
dynamically varied applying a DC voltage to the
FB pin. The DC voltage can come from a DAC
signal, or a filtered PWM signal. The advantage
of this approach is that a high frequency PWM
signal (>10kHz) can be used to control LED
intensity.
VIN
VIN
EN
SW
OUT
FB
VIN
GND
VIN
EN
SW
OUT
FB
Figure 3. OVP Circuit
PWM
GND
Start-Up and Inrush Current
During start-up, inrush current of approximately double
the nominal current flows to set up the inductor current
and the voltage on the output capacitor. If the inrush
current needs to be limited, a soft-start circuit similar to
Figure 4 could be implemented. The soft-start capacitor,
CSS, provides over-drive to the FB pin at start-up,
resulting in gradual increase of switch duty cycle and
limited inrush current.
Figure 1. PWM Dimming Method
VIN
VIN
EN
SW
VIN
OUT
FB
2200pF
CSS
5.11k
49.9k
GND
VIN
EN
SW
OUT
FB
DC
Equivalent
Figure 2. Continuous Dimming
GND
R
10k
Figure 4. One of Soft-Start Circuit
M9999-071007
July 2007
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Micrel, Inc.
MIC2289
6-Series LED Circuit without External Soft-Start
6-Series LED Circuit with External Soft-Start
L = 10µH
L = 10µH
C
C
V
IN = 1µF
OUT = 0.22µF
IN = 3.6V
CIN = 1µF
COUT = 0.22µF
VIN = 3.6V
IOUT = 20mA
6 LEDs
CSS = 2200pF
IOUT = 20mA
6 LEDs
TIME (100µs/dvi.)
TIME (100µs/dvi.)
Figure 5. 6-Series LED Circuit
without External Soft Start
Figure 6. 6-Series LED Circuit
with External Soft Start
M9999-071007
July 2007
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Micrel, Inc.
MIC2289
Package Information
6-Pin Thin SOT-23 (D6)
8-Pin MLF® (ML)
M9999-071007
July 2007
9
Micrel, Inc.
MIC2289
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2004 Micrel, Incorporated.
M9999-071007
July 2007
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