MIC2292/93
Micrel, Inc.
MIC2292/93
High Frequency PWM White LED Drivers with
Internal Schottky Diode and OVP
General Description
The MIC2292 and MIC2293 are high frequency, Pulse Width
Modulator (PWM) boost regulators optimized for constant-
current, white LED driver applications. Because of their
constant PWM switching frequencies of 1.6MHz and 2MHz,
respectively, the MIC2292/93 can use the smallest external
components, allowing designers to avoid sensitive IF bands
in their RF applications.
The products feature an internal Schottky diode and two
levels of output overvoltage protection allowing a small size
and efficient DC/DC solution that requires only four external
components.
The 2.5V to 10V input voltage range of MIC2292/3
allows direct operation from 1- and 2-cell Li Ion as well as
3- to 4-cell NiCad/NiMH/Alkaline batteries. The MIC2292/3
products are available in a small size 2mm
×
2mm 8-lead
MLF™ package and have 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.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
2.5V to 10V input voltage
Output voltage up to 34V
Internal Schottky diode
1.6MHz PWM operation (MIC2292)
2.0MHz PWM operation (MIC2293)
Stable with ceramic capacitors
15V and 34V output overvoltage protection options
500mA switch current rating
95mV feedback voltage
<1% line and load regulation
<1µA shutdown current
Over-temperature protection
UVLO
8-lead (2mm
×
2mm) MLF™package
–40°C to +125°C junction temperature range
Applications
• White LED driver for backlighting
– Cell phones
– PDAs
– GPS systems
– Digital cameras
– MP3 players
– IP phones
• Constant current power supplies
Typical Application
15µH
10µH
MIC2292-15BML
Li Ion
1µF
MIC2293-15BML
0.22µF
16V
Li Ion
1µF
VIN
EN
SW
VIN
EN
SW
OUT
FB
GND
95mV
6.3Ω
OUT
FB
GND
95mV
6.3Ω
0.22µF
16V
1.6MHz PWM White LED Driver with 15V OVP
2MHz PWM White LED Driver with 15V OVP
MLF and
MicroLeadFrame
are 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
July 2005
1
M9999-070105
MIC2292/93
Micrel, Inc.
Marking
Code
SWA
SWA
SWC
SWC
SZA
SZA
SZC
SZC
Overvoltage
Protection
15V
15V
34V
34V
15V
15V
34V
34V
Junction
Temp. Range
–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
–40°C to +125°C
Ordering Information
Part Number
MIC2292-15BML
MIC2292-15YML
MIC2292-34BML
MIC2292-34YML
MIC2293-15BML
MIC2293-15YML
MIC2293-34BML
MIC2293-34YML
Frequency
1.6MHz
1.6MHz
1.6MHz
1.6MHz
2MHz
2MHz
2MHz
2MHz
Package
8-lead MLF™
8-lead MLF™
8-lead MLF™
8-lead MLF™
8-lead MLF™
8-lead MLF™
8-lead MLF™
8-lead MLF™
Lead Finish
Standard
Pb-Free
Standard
Pb-Free
Standard
Pb-Free
Standard
Pb-Free
Pin Configuration
OUT
VIN
EN
AGND
1
2
3
4
8
7
6
PGND
SW
FB
NC
EP
5
8-lead MLF™ (BML)
(Top View)
Fused Lead Frame
Pin Description
Pin Number
1
2
3
5
6
7
4,8
EP
Pin Name
OUT
VIN
EN
NC
FB
SW
GND
GND
Pin Function
Output pin and overvoltage protection (Output): Connect to the output ca-
pacitor and LEDs.
Supply (Input): Input voltage.
Enable (Input): Logic high enables regulator. Logic low shuts down regula-
tor.
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.
Switch node (Input): Internal power transistor collector.
Ground (Return): Ground.
Ground (Return): Exposed backside pad.
M9999-070105
2
July, 2005
MIC2292/93
Micrel, Inc.
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ..................................................... 12V
Switch Voltage (V
SW
) ......................................–0.3V to 34V
Enable Pin Voltage (V
EN
) ................................... –0.3 to V
IN
FB Voltage (V
FB
) ............................................................. 6V
Switch Current (I
SW
) ........................................................ 2A
Ambient Storage Temperature (T
S
) .......... –65°C to +150°C
Schottky Reverse Voltage (V
DA
) ................................... 34V
ESD Rating
(3)
............................................................... 2kV
Operating Ratings
(2)
Supply Voltage (V
IN
) ..........................................2.5V to 10V
Output Voltage (V
OUT
) .......................................V
IN
to V
OVP
Junction Temperature Range (T
J
) ............ –40°C to +125°C
Package Thermal Impedance
8-lead MLF™ (θ
JA
) .............................................. 93°C/W
Electrical Characteristics
(4)
T
A
= 25ºC, V
IN
= V
EN
= 3.6V, V
OUT
= 15V, I
OUT
= 20mA, unless otherwise noted.
Bold
values indicate –40ºC ≤ T
J
≤ +125ºC.
Symbol
V
IN
V
ULVO
I
VIN
I
SD
V
FB
I
FB
Parameter
Supply Voltage Range
Under Voltage Lockout
Quiescent Current
Shutdown Current
Feedback Voltage
Feedback Input Current
Line Regulation
(6)
Load Regulation
(6)
D
MAX
I
SW
V
SW
I
SW
V
EN
I
EN
f
SW
V
D
I
RD
V
OVP
T
J
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
J
(max),
the junction-to-ambient thermal resistance,
θ
JA
, and the ambient temperature, T
A
. The maximum allowable power dissipation will result in excessive
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.
6. Guaranteed by design.
5. I
SD
= I
VIN
.
Condition
Min
2.5
1.8
Typ
2.1
2.5
0.1
Max
10
2.4
5
1
100
1
2
Units
V
V
mA
µA
mV
nA
%
%
%
mA
mV
V
FB
> 200mV, (not switching)
V
EN
= 0V
(5)
(±5%)
V
FB
= 95mV
3V ≤ V
IN
≤ 5V
5mA ≤ I
OUT
≤ 20mA
85
I
SW
= 0.5A
V
EN
= 0V, V
SW
= 10V
TURN ON
TURN OFF
V
EN
= 10V
MIC2292
MIC2293
I
D
= 150mA
V
R
= 30V
MIC2292/93-15
MIC2292/93-34
Hysteresis
13
30
1.4
1.75
1.5
90
95
-450
0.5
0.5
90
750
450
0.01
Maximum Duty Cycle
Switch Current Limit
Switch Saturation Voltage
Switch Leakage Current
Enable Threshold
Enable Pin Current
Oscillator Frequency
Schottky Forward Drop
Schottky Leakage Current
Overvoltage Protection
Overtemperature
Threshold Shutdown
5
0.4
µA
V
V
µA
MHz
MHz
V
µA
V
V
°C
°C
20
1.6
2.0
0.8
14
32
150
10
40
1.8
2.25
1
4
16
34
July 2005
3
M9999-070105
MIC2292/93
Micrel, Inc.
Typical Characteristics
Feedback Voltage
vs. Input Voltage
SHUTDOWN CURRENT (µA)
100
99
FB VOLTAGE (mV)
5
4
3
2
1
0
Shutdown Current
vs. Input Voltage
QUIESCENT CURRENT (mA)
5
4
3
2
1
0
Quiescent Current
vs. Input Voltage
98
97
96
95
94
93
92
91
90
0
2
4
6
V
IN
(V)
8
10
12
0
2
4
6
V
IN
(V)
8
10
12
0
2
4
6
V
IN
(V)
8
10
12
SWITCHING FREQUENCY (MHz)
1.4
1.2
50
45
40
IENABLE (µA)
SCHOTTKY FORWARD CURRENT (mA)
Switch Frequency
vs. Temperature
EN Pin Bias Current
vs. Temperature
700
600
500
400
300
200
100
Schottky Forward
Voltage Drop
1
0.8
0.6
0.4
0.2
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
35
30
25
I
EN
= 10V
20
I = 4.2V
15
E N
10
I
EN
= 3.6V
1050
SCHOTTKY FORWARD VOLTAGE DROP (mV)
SCHOTTKY LEAKAGE CURRENT (µA)
SATURATION VOLTAGE (mV)
2.5
2
1.5
1
0.5
Schottky Reverse
Leakage Current
550
500
450
400
350
300
-40
Saturation Voltage
vs. Temperature
CURRENT LIMIT (mA)
900
850
800
750
700
650
Current Limit
vs. Temperature
V
R
= 25V
V
R
= 16V
V
R
= 10V
0
30
I
S W
= 500mA
0
40
80
TEMPERATURE (°C)
120
40
50 60 70 80 90 100
TEMPERATURE (°C)
V = 2.5V
IN
600
-40
0
40
80
TEMPERATURE (°C)
120
SWITCHING FREQUENCY (MHz)
SATURATION VOLTAGE (mV)
2
1.6
1.2
0.8
0.4
0
-40
Switch Frequency
vs. Temperature
600
500
400
300
200
100
Switch Saturation Voltage
vs. Current
V
IN
= 2.5V
V
IN
= 5V
0
40
80
TEMPERATURE (°C)
120
0
0
100
200 300
I
SW
(mA)
400
500
M9999-070105
4
July, 2005
1150
5
I = 3.0V
EN
0
-50
0
50
TEMPERATURE (°C)
450
550
650
750
850
950
100
0
MIC2292/93
Micrel, Inc.
Functional Diagram
VIN
FB
EN
OUT
OVP*
SW
g
m
95mV
S
1.6MHz
or
2.0MHz
Oscillator
V
REF
PWM
Generator
Ramp
Generator
GND
MIC2292/93 Block Diagram
Functional Description
The MIC2292/93 is a constant frequency, PWM current mode
boost regulator. The block diagram is shown above. The
MIC2292/93 is composed of an oscillator, slope compensation
ramp generator, current amplifier, g
m
error amplifier, PWM
generator, 500mA bipolar output transistor, and Schottky
rectifier diode. The oscillator generates a 1.6MHz clock for the
MIC2292 and a 2.0MHz clock for the MIC2293. The clocks'
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.
July 2005
5
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:
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.
M9999-070105
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