MIC2289-15BML [MICREL]
2mm 】 2mm White LED Driver with Internal Schottky Diode and OVP; 2毫米】 2毫米白光LED驱动器，内置肖特基二极管和OVP
| 型号： | MIC2289-15BML |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 2mm 】 2mm White LED Driver with Internal Schottky Diode and OVP |
| 文件： | 总9页 (文件大小：90K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2289
2mm × 2mm White LED Driver
with 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
internalSchottkydiodeandthreelevelsofoutputovervoltage
protectionprovidingasmallsizeandefficientDC/DCsolution
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
• <1% line and load regulation
• <1mA shutdown current
• Overtemperature protection
• UVLO
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.
The MIC2289 implements a constant frequency 1.2MHz
PWM control scheme. The high frequency, PWM operation
saves board space by reducing external component sizes.
TheaddedbenefitoftheconstantfrequencyPWMschemein
caparison to varible 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
• White LED driver for backlighting
Cell phones
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.
PDAs
GPS systems
Digital cameras
MP3 players
IP phones
• LED flashlights
• Constant current power supplies
The MIC2289 is available in a 2mm × 2mm 8-pin MLF™
package and has a junction temperature range of –40°C to
+125°C.
All support documentation can be found on Micrel’s web
site at www.micrel.com.
Typical Application
3-Series LED Efficiency
10µH
82
80
78
76
74
MIC2289-15BML
VIN
SW
1-Cell
Li Ion
1µF
0.22µF/16V
OUT
FB
95mV
EN
72
GND
VIN =3.6V
6.3Ω
70
0
5
10
I
15
20
25
(mA)
OUT
3-Series White LED Driver
MicroLeadFrame and MLF are trademarks of Amkor Technology, Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-081104
August, 2004
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MIC2289
Micrel
Ordering Information
Marking Overvoltage
Junction
Part Number
Code
SNA
SNA
SNB
SNB
SNC
SNC
Protection
Temp. Range
Package
Lead Finish
Standard
MIC2289-15BML
MIC2289-15YML
MIC2289-24BML
MIC2289-24YML
MIC2289-34BML
MIC2289-34YML
15V
–40°C to 125°C 2mm × 2mm MLF™-8
–40°C to 125°C 2mm × 2mm MLF™-8
–40°C to 125°C 2mm × 2mm MLF™-8
–40°C to 125°C 2mm × 2mm MLF™-8
–40°C to 125°C 2mm × 2mm MLF™-8
–40°C to 125°C 2mm × 2mm MLF™-8
15V
Lead Free
Standard
24V
24V
Lead Free
Standard
34V
34V
Lead Free
Pin Configuration
OUT
VIN
1
2
3
4
8
PGND
SW
7
6
5
EN
FB
AGND
EP
NC
MLF™-8 (BML)
(Top View)
Fused Lead Frame
Pin Description
Pin Number
Pin Name
Pin Function
1
OUT
Output Pin and Overvoltage Protection (Output): Connect to the output
capacitor and LEDs
2
3
5
6
VIN
EN
NC
FB
Supply (Input): Input voltage.
Enable (Input): Logic high enables regulator, logic low shuts down regulator.
No connect (no internal connection to die).
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.
7
SW
Switch Node (Input): Internal power transistor collector.
Ground (Return): Ground.
4,8
EP
GND
GND
Ground (Return): Backside pad.
M9999-081104
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August, 2004
MIC2289
Micrel
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (V ) .....................................................12V
Supply Voltage (V ) ........................................ 2.5V to 10V
IN
IN
Switch Voltage (V ) ..................................... –0.3V to 34V
Output Voltage (V
) ..................................... V to V
OUT IN OVP
SW
Enable Pin Voltage (V )................................... –0.3 to V
Junction Temperature Range (T ) ........... –40°C to +125°C
EN
IN
J
FB Voltage (V ) .............................................................6V
Package Thermal Impedance
FB
Switch Current (I ) .......................................................2A
2mm × 2mmMLF™-8 (θ )..................................93°C/W
SW
JA
Ambient Storage Temperature (T ) ......... –65°C to +150°C
S
Schottky Reverse Voltage (V ) ...................................34V
DA
(3)
ESD Rating ................................................................ 2kV
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
VUVLO
IVIN
2.1
2.5
V
VFB > 200mV, (not switching)
VEN = 0V(5)
mA
µA
mV
nA
%
ISD
0.1
1
VFB
(±5%)
90
95
100
IFB
VFB = 95mV
–450
0.5
3V ≤ VIN ≤ 5V
1
2
Load Regulation
5mA ≤ IOUT ≤ 20mA
0.5
%
DMAX
ISW
VSW
ISW
Maximum Duty Cycle
Switch Current Limit
Switch Saturation Voltage
Switch Leakage Current
Enable Threshold
85
90
%
750
450
0.01
mA
mV
µA
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, T (max),
J
the junction-to-ambient thermal resistance, θ , and the ambient temperature, T . The maximum allowable power dissipation will result in excessive
JA
A
die temperature, and the regulator will go into thermal shutdown.
2. This device is not guaranteed to operate beyond its specified operating rating.
3. Devices are inherently ESD sensitive. Handling precautions required. Human body model.
4. Specification for packaged product only.
5.
I
= I
.
SD
VIN
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M9999-081104
MIC2289
Micrel
Typical Characteristics
Feedback Voltage
vs. Input Voltage
100
Shutdown Current
vs. Input Voltage
Quiescent Current
vs. Input Voltage
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
V
(V)
V
(V)
V
(V)
IN
IN
IN
Switch Frequency
vs. Temperature
EN Pin Bias Current
vs. Temperature
Schottky Forward
Voltage Drop
1.4
1.2
1
50
45
40
35
30
25
20
15
10
5
700
600
500
400
300
200
100
0
IEN = 10V
0.8
0.6
0.4
0.2
0
IEN = 4.2V
IEN = 3.0V
IEN = 3.6V
0
-40 -20
0
20 40 60 80 100
-50
0
50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
SCHOTTKY FORWARD VOLTAGE DROP (mV)
Schottky Reverse
Leakage Current
Saturation Voltage
vs. Temperature
Current Limit
vs. Temperature
900
2.5
2
550
500
450
400
350
300
850
800
750
700
VR = 25V
VR = 16V
VR = 10V
1.5
1
0.5
650
VIN = 2.5V
ISW = 500mA
0
600
30 40 50 60 70 80 90 100
-40
0
40
80
120
-40
0
40
80
120
TEMPERATURE (°C)
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
I
(mA)
SW
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August, 2004
MIC2289
Micrel
Functional Diagram
VIN
FB
EN
OUT
OVP
SW
PWM
Generator
gm
VREF
95mV
Σ
GND
1.2MHz
Ramp
Oscillator
Generator
MIC2289 Block Diagram
The g 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
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
m
of the g error amplifier provides the voltage-loop signal that
m
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, maintain-
ing the constant frequency current-mode PWM control. The
LED is set by the feedback resistor:
ramp generator, current amplifier, g error amplifier, PWM
m
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 compen-
sation 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 compensa-
tion ramp generator. This summed current-loop signal is fed
to one of the inputs of the PWM generator.
95mv
I
=
LED
R
FB
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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M9999-081104
MIC2289
Micrel
The table below shows recommended inductor and output
capacitor values for various series-LED applications:
External Component Selection
TheMIC2289canbeusedacrossawiderageofapplications.
Series LEDs
L
Manufacturer
Min COUT
Manufacturer
2
22µH
LQH32CN220K21 (Murata)
NLC453232T-220K(TDK)
2.2µF
0805ZD225KAT(AVX)
GRM40X5R225K10(Murata)
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
LQH32CN150K21 (Murata)
NLC453232T-150K(TDK)
1µF
0805ZD105KAT(AVX)
GRM40X5R105K10(Murata)
LQH32CN100K21 (Murata)
NLC453232T-100K(TDK)
0.22µF
0.22µF
0.22µF
2.2µF
0805ZD224KAT(AVX)
GRM40X5R224K10(Murata)
LQH32CN6R8K21 (Murata)
NLC453232T-6R8K(TDK)
0805ZD225KAT(AVX)
GRM40X5R225K10(Murata)
LQH32CN4R7K21 (Murata)
NLC453232T-4R7K(TDK)
0805ZD224KAT(AVX)
GRM40X5R224K10(Murata)
3
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
0805YD225MAT(AVX)
GRM40X5R225K16(Murata)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
1µF
0805YD105MAT(AVX)
GRM40X5R105K16(Murata)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
0.22µF
0.22µF
0.27µF
1µF
0805YD224MAT(AVX)
GRM40X5R224K16(Murata)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
0805YD224MAT(AVX)
GRM40X5R224K16(Murata)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
0805YD274MAT(AVX)
GRM40X5R224K16(Murata)
4
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
0805YD105MAT(AVX)
GRM40X5R105K25(Murata)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
1µF
0805YD105MAT(AVX)
GRM40X5R105K25(Murata)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
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
0805YD274MAT(AVX)
GRM40X5R274K25(Murata)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
0805YD274MAT(AVX)
GRM40X5R274K25(Murata)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
0805YD274MAT(AVX)
GRM40X5R274K25(Murata)
5, 6
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
7, 8
LQH43MN220K21 (Murata)
NLC453232T-220K(TDK)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
LQH43MN 150K21 (Murata)
NLC453232T-150K(TDK)
08053D224MAT(AVX)
GRM40X5R224K25(Murata)
LQH43MN 100K21 (Murata)
NLC453232T-100K(TDK)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
LQH43MN 6R8K21 (Murata)
NLC453232T-6R8K(TDK)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
LQH43MN 4R7K21 (Murata)
NLC453232T-4R7K(TDK)
08053D274MAT(AVX)
GRM40X5R274K25(Murata)
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MIC2289
Micrel
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 op-
tions 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 propor-
tionally with the amplitude of the control voltage.
The LED intensity (current) can be dynamically
variedapplyingaDCvoltagetotheFBpin. TheDC
voltage can come from a DAC signal, or a filtered
PWM signal . The advantage of this approach is
thatahighfrequencyPWMsignal(>10kHz)canbe
used to control LED intensity.
VIN
VIN
EN
SW
OUT
FB
VIN
GND
VIN
EN
SW
OUT
FB
Figure 3. MLF™ Package OVP Circuit
Start-Up and Inrush Current
PWM
GND
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
Figure 1. PWM Dimming Method
VIN
implemented. The soft-start capacitor, C , provides over-
SS
drive to the FB pin at start-up, resulting in gradual increase of
switch duty cycle and limited inrush current.
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
August, 2004
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M9999-081104
MIC2289
Micrel
6-Series LED Circuit without External Soft-Start
6-Series LED Circuit with External Soft-Start
L = 10µH
CIN = 1µF
L = 10µH
CIN = 1µF
COUT = 0.22µF
VIN = 3.6V
COUT = 0.22µF
VIN = 3.6V
IOUT = 20mA
6 LEDs
I
OUT = 20mA
6 LEDs
CSS = 2200pF
R = 10kΩ
TIME (100µs/div.)
TIME (100µs/div.)
Figure 6. 6-Series LED Circuit
without External Soft-Start
Figure 7. 6-Series LED Circuit
with External Soft-Start
M9999-081104
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August, 2004
MIC2289
Micrel
Package Information
8-Pin MLF™ (BML)
MICREL, INC. 1849 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2004 Micrel, Incorporated.
August, 2004
9
M9999-081104
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