MIC2287YD5 [MICREL]
1.2MHz PWM White LED Driver with OVP in 2mm 】 2mm MLF⑩ and Thin SOT-23; 1.2MHz的PWM白光LED驱动器，带有过压保护，采用2mm 】 2毫米MLF⑩和薄型SOT -23
| 型号： | MIC2287YD5 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 1.2MHz PWM White LED Driver with OVP in 2mm 】 2mm MLF⑩ and Thin SOT-23 |
| 文件： | 总10页 (文件大小：113K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2287
1.2MHz PWM White LED Driver with OVP in
2mm × 2mm MLF™ and Thin SOT-23
General Description
Features
The MIC2287 is a 1.2MHz pulse width modulated (PWM),
boost-switching regulator that is optimized for constant-
current, white LED driver applications. With a maximum
outputvoltageof34Vandaswitchcurrentofover500mA, the
MIC2287easilydrivesastringofupto8whiteLEDsinseries,
ensuring uniform brightness and eliminating several ballast
resistors.
• 2.5V to 10V input voltage
• Output voltage up to 34V
• Over 500mA switch current
• 1.2 MHz PWM operation
• 95mV feedback voltage
• Output Overvoltage Protection (OVP)
• Options for 15V, 24V, and 34V OVP
• <1% line and load regulation
• <1µA shutdown current
• Over-temperature protection
• UVLO
• Low profile Thin SOT-23-5 package option
• 8-lead 2mm × 2mm MLF™ package option
• –40°C to +125°C junction temperature range
The MIC2287 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
as opposed to variable frequency topologies is much lower
noise and input ripple injected back to the battery source.
To optimize efficiency, the feedback voltage is set to only
95mV. This reduces the power dissipation in the current set
resistor and allows the lowest total output voltage, hence
minimal current draw from the battery.
Applications
• White LED driver for backlighting:
- Cell phones
The MIC2287 is available with 3 levels of overvoltage protec-
tion, 15V, 24V, and 34V. This allows designers to choose the
smallest possible external components with the appropriate
voltage ratings for their applications.
- PDAs
- GPS systems
- Digital cameras
- MP3 players
- IP phones
• Photo flash LED driver
• LED flashlights
• Constant current power supplies
The MIC2287 is available in low profile Thin SOT-23 5-lead
and an 8-lead 2mm × 2mm MLF™ package options. The
MIC2287 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
CMDSH-3
CMDSH-3
10µH
10µH
MIC2287BD5
MIC2287-34BML
5
4
1
3
VIN
SW
VIN
EN
SW
1-Cell
Li Ion
1µF
1-Cell
Li Ion
1µF
OVP
0.22µF
0.22µF
FB
EN
95mV
FB
95mV
GND
GND
2
6.3Ω
6.3Ω
3-Series White LED Driver in Thin SOT-23
6-Series White LED Driver
with Output OVP in 2mm × 2mm MLF™-8
MLF and MicroLeadFrame 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
M0510-081104
August 2004
1
MIC2287
Micrel
Ordering Information
Marking
Overvoltage
Protection
Junction
Temp. Range
Part Number
Code
SGAA
SGAA
SLA
Package
Lead Finish
Standard
Lead Free
Standard
Lead Free
Standard
Lead Free
Standard
Lead Free
MIC2287BD5
N/A
N/A
15V
15V
24V
24V
34V
34V
–40°C to 125°C
–40°C to 125°C
Thin SOT-23-5
Thin SOT-23-5
MIC2287YD5
MIC2287-15BML
MIC2287-15YML
MIC2287-24BML
MIC2287-24YML
MIC2287-34BML
MIC2287-34YML
–40°C to 125°C 2mm x 2mm MLF™
–40°C to 125°C 2mm x 2mm MLF™
–40°C to 125°C 2mm x 2mm MLF™
–40°C to 125°C 2mm x 2mm MLF™
–40°C to 125°C 2mm x 2mm MLF™
–40°C to 125°C 2mm x 2mm MLF™
SLA
SLB
SLB
SLC
SLC
Pin Configuration
FB GND SW
1
3
2
OVP
1
2
3
8
PGND
SW
VIN
EN
7
6
5
FB
4
5
EP
AGND
4
NC
EN
VIN
TSOT-23-5 (BD5)
8-Pin MLF™ (BML)
(Top View)
Fused Lead Frame
Pin Description
Pin Number
Pin Number
TSOT-23-5 2mm ×2mm MLF™ Pin Name
Pin Function
1
2
3
7
6
SW
GND
FB
Switch node (Input): Internal power BIPOLAR collector.
Ground (Return): Ground.
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
2
EN
VIN
Enable (Input): Logic high enables regulator. Logic low shuts down regulator.
Supply (Input): 2.5V to 10V for internal circuitry.
Overvoltage protection (Input): Connect to the output.
Analog ground.
5
—
—
—
—
—
1
OVP
AGND
PGND
NC
4
8
Power ground.
5
No connect (no internal connection to die).
Ground (Return): Exposed backside pad.
EP
GND
M0510-081104
2
August 2004
MIC2287
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
Junction Temperature Range (T ) ........... –40°C to +125°C
SW
J
Enable Pin Voltage (V )................................... –0.3 to V
Package Thermal Impedance
EN
IN
FB Voltage (V ) .............................................................6V
2mm × 2mmMLF™ (θ ) .....................................93°C/W
FB
JA
Switch Current (I ) .......................................................2A
Thin SOT-23-5 (θ ) ..........................................256°C/W
SW
JA
Ambient Storage Temperature (T ) ......... –65°C to +150°C
S
(3)
ESD Rating ................................................................ 2kV
Electrical Characteristics(4)
TA = 25°C, VIN = VEN = 3.6V, VOUT = 10V, IOUT = 10mA, 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
IEN
Enable Pin Current
Oscillator Frequency
Overvoltage Protection
VEN = 10V
20
µA
fSW
1.05
1.2
1.35
MHz
VOVP
MIC2287BML- 15 only
MIC2287BML- 24 only
MIC2287BML- 34 only
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 ratings.
3. Devices are inherently ESD sensitive. Handling precautions required. Human body model.
4. Specification for packaged product only.
5.
I
= I
.
SD
VIN
August 2004
3
M0510-081104
MIC2287
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
6 Series LED Efficiency
3 Series LED Efficiency
Switch Frequency
vs. Temperature
1.4
1.2
1
VIN = 4.2V
84
82
80
78
76
74
72
70
84
82
80
78
76
74
VIN = 3.0V
VIN = 3.6V
0.8
0.6
0.4
VIN = 3.0V
VIN = 3.6V
VIN = 4.2V
L = 10µH
COUT = 0.22µF
L = 10µH
COUT = 0.22µF
72
70
0.2
0
10
I
15
(mA)
20
25
0
5
0
5
10
15
(mA)
20
25
0
40
80
120
-40
I
OUT
TEMPERATURE (°C)
OUT
EN Pin Bias Current
vs. Temperature
Saturation Voltage
vs. Temperature
Current Limit
vs. Temperature
50
45
40
35
30
25
20
15
550
500
450
400
900
850
800
750
700
IEN = 10V
IEN = 4.2V
IEN = 3.0V
IEN = 3.6V
10
5
0
350
300
650
600
ISW = 500mA
VIN = 2.5V
0
50
100
-50
0
40
80
120
-40
-40
0
40
80
120
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Switch Saturation Voltage
vs. Current
600
500
400
300
200
VIN = 2.5V
VIN = 5V
100
0
0
100 200 300 400 500
(mA)
I
SW
M0510-081104
4
August 2004
MIC2287
Micrel
Functional Diagram
VIN
FB
OVP*
EN
OVP*
SW
PWM
Generator
gm
VREF
95mV
Σ
GND
1.2MHz
Ramp
Oscillator
Generator
*
OVP available on MLFTM package option only
MIC2287 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 MIC2287 is a constant frequency, PWM current mode
boost regulator. The block diagram is shown above. The
MIC2287 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, and a 500mA bipolar output transistor. The oscil-
latorgeneratesa1.2MHzclock. Theclock’stwofunctionsare
to trigger the PWM generator that turns on the output transis-
tor 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.
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.
August 2004
5
M0510-081104
MIC2287
Micrel
The table below shows recommended inductor and output
capacitor values for various series-LED applications.
External Component Selection
TheMIC2287canbeusedacrossawiderageofapplications.
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)
M0510-081104
6
August 2004
MIC2287
Micrel
Dimming Control
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, as well as smallest
size and lowest cost. The OVP will clamp the output voltage
to within the specified limits. For the Thin SOT-23-5 package,
an OVP pin is not available. An external zener diode can be
connectedfromtheoutputoftheconvertertoFBpinasshown
in Figure 4. to implement similar protection.
There are two techniques for dimming control. One is PWM
dimming, and the other is continuous dimming.
1. PWM dimming control is implemented by applying
a PWM signal on EN pin as shown in Figure 1. The
MIC2287 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
PWM frequency should be between 100Hz and
10kHz.
VIN
2. Continuous dimming control is implemented by
applying a DC control voltage to the FB pin of the
MIC2287 through a series resistor as shown in
Figure 2. The LED intensity (current) can be dy-
namically 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
approachisahighfrequencyPWMsignal(>10kHz)
that can be used to control LED intensity.
VIN
EN
SW
FB
GND OVP
Figure 3. MLF™ Package OVP Circuit
VIN
VIN
VIN
EN
SW
FB
VIN
EN
SW
FB
5.11k
PWM
GND
GND
Figure 4. Thin SOT-23 Package OVP Circuit
Start-Up and Inrush Current
Figure 1. PWM Dimming Method
VIN
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 5 could be
VIN
EN
SW
FB
implemented. The soft-start capacitor, C , provides over-
5.11k
49.9k
SS
drive to the FB pin at start-up, resulting in gradual increase of
switch duty cycle and limited inrush current.
GND
VIN
DC
Equivalent
CSS
2200pF
Figure 2. Continuous Dimming
VIN
EN
SW
FB
Open-Circuit Protection
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 MIC2287 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 MIC2287 has 3
product options in the 8-lead 2mm × 2mm MLF™ with
overvoltage protection (OVP). The extra pins of the 8-lead
2mm × 2mm MLF™ package allow a dedicated OVP monitor
R
10k
GND
Figure 5. Soft-Start Circuit
August 2004
7
M0510-081104
MIC2287
Micrel
6-Series LED Circuit with External Soft-Start
6-Series LED Circuit without 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.)
M0510-081104
8
August 2004
MIC2287
Micrel
Package Information
All Dimensions are in millimeters
5-Pin TSOT (BD5)
8-Pin MLF™ (BML)
August 2004
9
M0510-081104
MIC2287
Micrel
Recommended Land Pattern for MLF™ 2×2 8 Lead
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.
M0510-081104
10
August 2004
相关型号：
MIC2288BD5TR
Switching Regulator, Current-mode, 1350kHz Switching Freq-Max, PDSO5, TSOT-23, 5 PIN
MICREL
MIC2288YD5TR
2A SWITCHING REGULATOR, 1350kHz SWITCHING FREQ-MAX, PDSO5, LEAD-FREE, TSOT-23, 5 PIN
MICROCHIP
MIC2288YMLTR
2A SWITCHING REGULATOR, 1350kHz SWITCHING FREQ-MAX, PDSO8, 2 X 2 MM, LEAD-FREE, MLF-8
MICROCHIP
©2020 ICPDF网 联系我们和版权申明