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MIC2287-34YML-TR

P1-P3P4-P6P7-P9P10-P10
MIC2287 Micrel, Inc.
M9999-070105 4 July 2005
Typical Characteristics
90
91
92
93
94
95
96
97
98
99
100
0 2 4 6 8
10 12
FB VOLTAGE (mV)
V
IN
(V)
Feedback Voltage
vs. Input Voltage
0
1
2
3
4
5
0 2 4 6 8
10 12
SHUTDOWN CURRENT (µA)
V
IN
(V)
Shutdown Current
vs. Input Voltage
70
72
74
76
78
80
82
84
EFFICIENCY (%
)
I
OUT
(mA)
3 Series LED Efficiency
L = 10µH
C
OUT
= 0.22µF
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 3.0V
0
5
10 15 20 25
70
72
74
76
78
80
82
84
EFFICIENCY (%
)
I
OUT
(mA)
6 Series LED Efficiency
L = 10µH
C
OUT
= 0.22µF
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 3.0V
0 5
10
15 20 25
0
0.2
0.4
0.6
0.8
1
1.2
1.4
-40
0 40 8
0 120
SWITCHING FREQUENCY (MHz)
TEMPERATURE (°C)
Switch Frequency
vs.
Temperature
0
5
10
15
20
25
30
35
40
45
50
-50
0 50 100
IENABLE (µA)
TEMPERATURE (°C)
EN Pin Bias Currency
vs.
Temperature
I
EN
= 4.2V
I
EN
= 3.6V
I
EN
= 3.0V
I
EN
= 10V
300
350
400
450
500
550
-40
0 40 8
0 120
SATURATION VOL
T
AGE (mV)
TEMPERATURE (°C)
Saturation Voltage
vs.
Temperature
I
SW
= 500mA
600
650
700
750
800
850
900
-40 0 40 80 120
CURRENT LIMIT (mA)
TEMPERATURE (°C)
Current Limit
vs.
Temperature
V
IN
= 2.5
V
0
100
200
300
400
500
600
0 100 200 300 400 500
SATURATION VOL
T
AGE (mV)
I
SW
(mA)
Switch Saturation Voltage
vs. Current
V
IN
= 2.5V
V
IN
= 5V
July 2005 5 M9999-070105
MIC2287 Micrel, Inc.
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
ramp generator, current amplifier, g
m
error amplifier, PWM
generator, and a 500mA bipolar output transistor. The oscil-
lator 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 genera-
tor. The current amplifier is used to measure the switch cur-
rent 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.
Functional Diagram
GND
V
REF
PWM
Generator
Ramp
Generator
1.2MHz
Oscillator
SW
ENFB
OVP*
VIN
95mV
*OVP available on MLF
TM
package option only
g
m
OVP*
S
MIC2287 Block Diagram
The g
m
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 g
m
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, maintain-
ing the constant frequency current-mode PWM control. The
LED is set by the feedback resistor:
I
LED
=
95mv
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.
MIC2287 Micrel, Inc.
M9999-070105 6 July 2005
External Component Selection
The MIC2287 can be used across a wide rage of applications.
The table below shows recommended inductor and output
capacitor values for various series-LED applications.
Series LEDs L Manufacturer Min C
OUT
Manufacturer
2 22µH LQH32CN220K21 (Murata) 2.2µF 0805ZD225KAT(AVX)
NLC453232T-220K(TDK) GRM40X5R225K10(Murata)
15µH LQH32CN150K21 (Murata) 1µF 0805ZD105KAT(AVX)
NLC453232T-150K(TDK) GRM40X5R105K10(Murata)
10µH LQH32CN100K21 (Murata) 0.22µF 0805ZD224KAT(AVX)
NLC453232T-100K(TDK) GRM40X5R224K10(Murata)
6.8µH LQH32CN6R8K21 (Murata) 0.22µF 0805ZD225KAT(AVX)
NLC453232T-6R8K(TDK) GRM40X5R225K10(Murata)
4.7µH LQH32CN4R7K21 (Murata) 0.22µF 0805ZD224KAT(AVX)
NLC453232T-4R7K(TDK) GRM40X5R224K10(Murata)
3 22µH LQH43MN220K21 (Murata) 2.2µF 0805YD225MAT(AVX)
NLC453232T-220K(TDK) GRM40X5R225K16(Murata)
15µH LQH43MN 150K21 (Murata) 1µF 0805YD105MAT(AVX)
NLC453232T-150K(TDK) GRM40X5R105K16(Murata)
10µH LQH43MN 100K21 (Murata) 0.22µF 0805YD224MAT(AVX)
NLC453232T-100K(TDK) GRM40X5R224K16(Murata)
6.8µH LQH43MN 6R8K21 (Murata) 0.22µF 0805YD224MAT(AVX)
NLC453232T-6R8K(TDK) GRM40X5R224K16(Murata)
4.7µH LQH43MN 4R7K21 (Murata) 0.27µF 0805YD274MAT(AVX)
NLC453232T-4R7K(TDK) GRM40X5R224K16(Murata)
4 22µH LQH43MN220K21 (Murata) 1µF 0805YD105MAT(AVX)
NLC453232T-220K(TDK) GRM40X5R105K25(Murata)
15µH LQH43MN 150K21 (Murata) 1µF 0805YD105MAT(AVX)
NLC453232T-150K(TDK) GRM40X5R105K25(Murata)
10µH LQH43MN 100K21 (Murata) 0.27µF 0805YD274MAT(AVX)
NLC453232T-100K(TDK) GRM40X5R274K25(Murata)
6.8µH LQH43MN 6R8K21 (Murata) 0.27µF 0805YD274MAT(AVX)
NLC453232T-6R8K(TDK) GRM40X5R274K25(Murata)
4.7µH LQH43MN 4R7K21 (Murata) 0.27µF 0805YD274MAT(AVX)
NLC453232T-4R7K(TDK) GRM40X5R274K25(Murata)
5, 6 22µH LQH43MN220K21 (Murata) 0.22µF 08053D224MAT(AVX)
NLC453232T-220K(TDK) GRM40X5R224K25(Murata)
15µH LQH43MN 150K21 (Murata) 0.22µF 08053D224MAT(AVX)
NLC453232T-150K(TDK) GRM40X5R224K25(Murata)
10µH LQH43MN 100K21 (Murata) 0.27µF 08053D274MAT(AVX)
NLC453232T-100K(TDK) GRM40X5R274K25(Murata)
6.8µH LQH43MN 6R8K21 (Murata) 0.27µF 08053D274MAT(AVX)
NLC453232T-6R8K(TDK) GRM40X5R274K25(Murata)
4.7µH LQH43MN 4R7K21 (Murata) 0.27µF 08053D274MAT(AVX)
NLC453232T-4R7K(TDK) GRM40X5R274K25(Murata)
7, 8 22µH LQH43MN220K21 (Murata) 0.22µF 08053D224MAT(AVX)
NLC453232T-220K(TDK) GRM40X5R224K25(Murata)
15µH LQH43MN 150K21 (Murata) 0.22µF 08053D224MAT(AVX)
NLC453232T-150K(TDK) GRM40X5R224K25(Murata)
10µH LQH43MN 100K21 (Murata) 0.27µF 08053D274MAT(AVX)
NLC453232T-100K(TDK) GRM40X5R274K25(Murata)
6.8µH LQH43MN 6R8K21 (Murata) 0.27µF 08053D274MAT(AVX)
NLC453232T-6R8K(TDK) GRM40X5R274K25(Murata)
4.7µH LQH43MN 4R7K21 (Murata) 0.27µF 08053D274MAT(AVX)
NLC453232T-4R7K(TDK) GRM40X5R274K25(Murata)
P1-P3P4-P6P7-P9P10-P10

MIC2287-34YML-TR

Mfr. #:
Buy MIC2287-34YML-TR
Manufacturer:
Microchip Technology / Micrel
Description:
LED Lighting Drivers White LED Driver w/ 34V OVP
Lifecycle:
New from this manufacturer.
Delivery:
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