December 2000
1
MIC2142
MIC2142
Micrel
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
MIC2142
Micropower Boost Converter
Preliminary Information
General Description
The MIC2142 is a micropower boost switching regulator
housed in a SOT23-5 package. The input voltage range is
between 2.2V to 16V, making the device suitable for one-cell
Li Ion and 3 to 4-cell alkaline/NiCad/NiMH applications. The
output voltage of the MIC2142 can be adjusted up to 22V.
The MIC2142 is well suited for portable, space-sensitive
applications. It features a low quiescent current of 85
A, and
a typical shutdown current of 0.1
A. It's 330kHz operation
allows small surface mount external components to be used.
The MIC2142 is capable of efficiences over 85% in a small
board area.
The MIC2142 can be configured to efficiently power a variety
of loads. It is capable of providing a few mA output for
supplying low power bias voltages; it is also capable of
providing the 80mA needed to drive 4 white LEDs.
The MIC2142 is available in a SOT23-5 package with an
ambient operating temperature range from 40
C to +85
C
Features
2.2V to 16V input voltage
Up to 22V output voltage
330kHz switching frequency
0.1
A shutdown current
85
A quiescent current
Implements low-power boost, SEPIC, or flyback
SOT23-5 package
Applications
LCD bias supply
White LED driver
12V Flash memory supply
Local 3V to 5V conversion
Typical Application
R2
365k
R1
124k
+5V @60mA
2.8V to 4.7V
V
IN
L1
33
H
D1
MIC2142
5
3
4
2
1
VCC SW
FB
GND
EN
C
IN
10
F
C
OUT
22
F
Typical Configuration
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0
10
20
30
40
50
60
70
EFFICIENCY (%)
OUTPUT CURRENT (mA)
Efficiency
vs. Output Current
V
IN
= 4.2V
V
IN
= 3.0V
Efficiency vs. Output Current
MIC2142
Micrel
MIC2142
2
December 2000
Pin Configuration
VCC
EN
FB
SW
1
3
4
5
2
GND
Part
Identification
SBAA
SOT23-5 (BM5)
Pin Description
Pin Number
Pin Name
Pin Function
1
VCC
Chip Supply: +2.2V to +16V
2
GND
Ground: Return for internal circuitry and internal MOSFET (switch) source.
3
SW
Switch Node (Input): Internal MOSFET drain; 22V maximum.
4
FB
Feedback (Input): Output voltage sense node.
5
EN
Shutdown: Device shuts down to 0.1
A typical supply current.
Ordering Information
Part Number
Voltage
Ambient Temp. Range
Package
MIC2142BM5
Adj
40
C to +85
C
SOT23-5
December 2000
3
MIC2142
MIC2142
Micrel
Absolute Maximum Ratings (Note 1)
Supply voltage (V
CC
) ..................................................... 18V
Switch voltage (V
SW
) .................................................... 24V
Enable pin voltage (V
EN
) Note 3 ................................... 18V
Feedback Voltage (V
FB
)
Adjustable version ....................................................... 8V
Ambient Storage Temperature (T
S
) ......... 65
C to +150
C
Operating Ratings (Note 2)
Supply Voltage (V
CC
) ....................................... 2.2V to 16V
Enable pin voltage (V
EN
) Note 3 ......................... 0V to 16V
Switch Voltage (V
SW
) .................................................... 22V
Ambient Temperature (T
A
) ......................... 40
C to +85
C
Junction Temperature Range (T
J
) ........... 40
C to +125
C
Package Thermal Impedance
JA
SOT23-5 ..................................................... 220
C/W
Electrical Characteristics
V
CC
=3.6V, V
OUT
= 5V, I
OUT
= 20mA, T
A
=25
C; unless otherwise specified. Bold values indicate 25
C
T
J
125
C.
Parameter
Condition
Min
Typ
Max
Units
Input Voltage
2.2
16
V
Quiescent Current
V
EN
= ON , V
FB
= 2.2V
85
125
A
V
EN
= OFF (shutdown)
0.1
2
A
Feedback Voltage (V
FB
)
(
2%)
1.254
1.28
1.306
V
(
3%)
1.241
1.312
V
Comparator Hysteresis
18
mV
Feedback Input Bias Current
30
nA
Note 4
Enable Input Voltage
V
IH
(turn on)
0.6V
CC
0.55V
CC
V
V
IL
(turn off)
1.1
0.8
V
Enable Input Current
1
0.01
1
A
Load Regulation
200
A
I
OUT
20mA
0.2
%V
OUT
Line Regulation
2.2V
V
CC
16V; I
OUT
= 4mA
0.25
%/V
SW on Resistance
I
SW
= 100mA, V
CC
= 2.5V
5
I
SW
= 100mA, V
CC
= 12V
2
Switch Leakage Current
V
EN
= OFF, V
SW
= 12V
0.05
1
A
Oscillator Frequency
295
330
365
kHz
Duty Cycle
50
57
65
%
Note 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,
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. The
JA
of the power SOT23-5 is 220
C/W
mounted on a PC board.
Note 2:
The device is not guaranteed to function outside its operating rating.
Note 3:
V
EN
must be
V
IN
Note 4:
The maximum suggested value of the programming resistor, whose series resistance is measured from feedback to ground, is 124k
. Use of
larger resistor values can cause errors in the output voltage due to the feedback input bias current.
Note 5:
Devices are ESD sensitive, handling precautions required.
MIC2142
Micrel
MIC2142
4
December 2000
Typical Characteristics
0
50
100
150
200
250
300
350
0
2
4
6
8
10 12 14 16
QUIESCENT CURENT (
A)
INPUT VOLTAGE (V)
Quiescent Current
vs. Input Voltage
V
OUT
= 5V
14
14.5
15
15.5
16
16.5
2
4
6
8
10
12
14
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Line Regulation
I
L
= 2mA
L = 220
H
I
L
= 7mA
L = 22
H
0
200
400
600
800
1000
1200
0
2
4
6
8
10
12
14
OUTPUT RIPPLE (mV)
INPUT VOLTAGE (V)
Output Ripple
vs. Input Voltage
I
L
= 7mA
L = 22
H
V
OUT
= 15V
I
L
= 2mA
L = 220
H
60
65
70
75
80
85
2
4
6
8
10
12
14
EFFICIENCY (%)
INPUT VOLTAGE (V)
Efficiency
vs. Input Voltage
V
OUT
= 15V
I
L
= 7mA
L = 22
H
I
L
= 2mA
L = 220
H
0
2
4
6
8
10
12
14
16
0
5
10
15
20
25
30
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
MIC2142 Load
Regulation
V
REF
V
OUT
L = 22
H
V
IN
= 5V
0
50
100
150
200
250
300
350
0
2
4
6
8
10
12
14
FREQUENCY (kHz)
INPUT VOLTAGE (V)
Oscillator Characteristics
vs. Input Voltage
Duty Cycle
Frequency
0.40
0.45
0.50
0.55
0.60
0.65
DUTY CYCLE
V
O
= 15V
I
O
= 100
A
L= 220
H
70
72
74
76
78
80
82
84
-50 -30 -10 10 30 50 70 90 110
QUIESCENT CURRENT (
A)
TEMPERATURE (
C)
Quiescent Current
vs. Temperature
V
IN
= 3.6V
14.90
14.95
15.00
15.05
15.10
15.15
15.20
-50 -30 -10 10 30 50 70 90 110
OUTPUT VOLTAGE (V)
TEMPERATURE (
C)
V
OUT
and V
REF
Over Temperature
V
REF
V
OUT
1.270
1.275
1.280
1.285
1.290
REFERENCE VOLTAGE (V)
V
IN
=
3.6V
I
O
= 100
A
L = 22
H
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
-50 -30 -10 10 30 50 70 90 110
t
ON
(
sec)
TEMPERATURE (
C)
t
ON
vs.
Temperature
295
300
305
310
315
320
325
330
335
340
-50 -30 -10 10 30 50 70 90 110
FREQUENCY (kHz)
TEMPERATURE (
C)
Frequency vs.
Temperature
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-50 -30 -10 10 30 50 70 90 110
OSCILLATOR CHARACTERISTICS
TEMPERATURE (
C)
Timing Characteristics
Over Temperature
T (
sec)
t
ON
(
sec)
Duty Cycle
0
100
200
300
400
500
600
0
2
4
6
8
10
12
14
V
DS
(V)
INPUT VOLTAGE (V)
VDS and R
DS(ON)
vs. Input Voltage
0
1
2
3
4
5
6
R
DS(ON)
I
SW
= 100mA
December 2000
5
MIC2142
MIC2142
Micrel
0
1
2
3
4
5
6
7
-50 -30 -10 10 30 50 70 90 110
R
DS(ON)
(
)
TEMPERATURE (
C)
R
DS(ON)
vs.
Temperature
V
CC
=3.3V
V
CC
= 4.5V
0.4
0.42
0.44
0.46
0.48
0.5
0.52
0.54
0.56
0.58
0.6
-50 -30 -10 10 30 50 70 90 110
DUTY CYCLE (%)
TEMPERATURE (
C)
Timing Characteristics
Over Temperature
MIC2142
Micrel
MIC2142
6
December 2000
Functional Description
This MIC2142 is a fixed duty cycle, constant frequency, gated
oscillator, micropower, switch-mode power supply controller.
Quiescent current for the MIC2142 is only 85
A in the switch
off state, and since a MOSFET output switch is used, addi-
tional switch drive current is minimized. Efficiencies above
85% throughout most operating conditions can be realized.
A functional block diagram is shown above and typical
schematic is shown on page 1. Regulation is performed by a
hysteretic comparator, which regulates the output voltage by
gating the internal oscillator. The internal oscillator operates
at a fixed 57% duty cycle and 330kHz frequency. For the fixed
output versions, the output is divided down internally and then
compared to the internal V
REF
input. An external resistive
divider is use for the adjustable version.
The comparator has hysteresis built into it, which determines
the amount of low frequency ripple that will be present on the
Functional Diagram
330kHz
FIXED DUTY CYCLE
FB
EN
VCC
GND
SW
Oscillator
MIC2142
Bandgap
Reference
Shutdown
output. Once the feedback input to the comparator exceeds
the control voltage by 18mV, the high frequency oscillator
drive is removed from the output switch. As the feedback
input to the comparator returns to the reference voltage level,
the comparator is reset and the high frequency oscillator is
again gated to the output switch. The 18mV of hysteresis
seen at the comparator will be multiplied by the ratio of the
output voltage to the reference voltage. For a five volt output
this ratio would be 4, corresponding to a ripple voltage of
72mV at the output.
The maximum output voltage is limited by the voltage capa-
bility of the output switch. Output voltages up to 22V can be
achieved with a standard boost circuit. Higher output volt-
ages can be realized with a flyback configuration.
December 2000
7
MIC2142
MIC2142
Micrel
Application Information
Predesigned circuit information is at the end of this section.
Component Selection
Resistive Divider (Adjustable Version)
The external resistive divider should divide the output voltage
down to the nominal reference voltage. Current drawn through
this resistor string should be limited in order to limit the effect
on the overall efficiency. The maximum value of the resistor
string is limited by the feedback input bias current and the
potential for noise being coupled into the feedback pin. A
resistor string on the order of 2M
limits the additional load
on the output to 20
A for a 20V output. In addition, the
feedback input bias current error would add a nominal 60mV
error to the expected output. Equation 1 can be used for
determining the values for R2 and R1.
(1)
V
R1 R2
R1
V
OUT
REF
=
+
Boost Inductor
Maximum power is delivered to the load when the oscillator
is gated
on 100% of the time. Total output power and circuit
efficiency must be considered when determining the maxi-
mum inductor value. The largest inductor possible is prefer-
able in order to minimize the peak current and output ripple.
Efficiency can vary from 80% to 90% depending upon input
voltage, output voltage, load current, inductor, and output
diode.
Equation 2 solves for the output current capability for a given
inductor value and expected efficiency. Figures 7 through 12
show estimates for maximum output current assuming the
minimum duty and maximum frequency and 80% efficiency.
To determine the necessary inductance, find the intersection
between the output voltage and current, and then select the
value of the inductor curve just above the intersection. If the
efficiency is expected to be different than the 85% used for the
graph, Equation 2 can then be used to better determine the
maximum output capability.
The peak inductor/switch current can be calculated from
Equation 3 or read from the graph in Figure 13. The peak
current shown in the graph in Figure 13 is derived assuming
a max duty cycle and a minimum frequency. The selected
inductor and diode peak current capability must be greater
than this. The peak current seen by the inductor is calculated
at the maximum input voltage. A wide ranging input voltage
will result in a higher worst case peak current in the inductor
than a narrow input range.
(2)
I
V
t
2L
T
V
eff
V
O(max)
IN(min) ON
MAX
S
O
IN min
=
(
)
-
( )
2
1
(3)
I
t
V
L
PK
ON max
IN max
MIN
=
(
)
(
)
Table 1 lists common inductors suitable for most applica-
tions. Due to the internal transistor peak current limitation at
low input voltages, inductor values less than 10
H are not
recommmended. Table 6 lists minimum inductor sizes versus
input and output voltage. In low-cost, low-peak-current appli-
cations, RF-type leaded inductors may sufficient. All induc-
tors listed in Table 5 can be found within the selection of
CR32- or LQH4C-series inductors from either Sumida or
muRata.
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Table 1. Inductor Examples
Boost Output Diode
Speed, forward voltage, and reverse current are very impor-
tant in selecting the output diode. In the boost configuration
the average diode current is the same as the average load
current and the peak is the same as the inductor and switch
current. The peak current is the same as the peak inductor
current and can be derived from Equation 3 or the graph in
Figure 13. Care must be taken to make sure that the peak
current is evaluated at the maximum input voltage.
The BAT54 and BAT85 series are low current Shottky diodes
available from "On Semiconductor" and "Phillips" respec-
tively. They are suitable for peak repetitive currents of 300mA
or less with good reverse current characteristics. For applica-
tions that are cost driven, the 1N4148 or equivalent will
provide sufficient switching speed with greater forward drop
and reduced cost. Other acceptable diodes are On
Semiconductor's MBR0530 or Vishay's B0530, although
they can have reverse currents that exceed 1 mA at very high
junction temperatures. Table 2 summarizes some typical
performance characteristics of various suitable diodes.
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D
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a
A
m
0
0
1
C
5
2
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D
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t
a
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0
0
1
m
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a
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V
5
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5
1
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a
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2
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5
2
3
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A
5
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2
A
0
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3
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M
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4
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4
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1
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6
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0
)
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5
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1
(
V
5
9
.
0
A
n
5
2
)
V
0
2
(
A
2
.
0
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V
0
2
(
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A
B
V
4
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5
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V
5
4
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n
0
1
)
V
5
2
(
A
1
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0
2
(
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A
B
4
5
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A
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Table 2. Diode Examples
Output Capacitor
Due to the limited availability of tantalum capacitors, ceramic
capacitors and inexpensive electrolyics may be preferred.
Selection of the capacitor value will depend upon the peak
inductor current and inductor size. MuRata offers the GRM
series with up to 10uF @ 25V with a Y5V temperature
coefficient in a 1210 surface mount package. Low cost
applications can use the M series leaded electrolytic capaci-
tor from Panasonic. In general, ceramic, electrolytic, or
tantalum values ranging from 1
F to 22
F can be used for the
output capacitor.
MIC2142
Micrel
MIC2142
8
December 2000
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Table 3. Capacitor Examples
Design Example
Given a design requirement of 12V output and 1mA load with
an miniumum input voltage of 2.5V, Equation 2 can be used
to calculate to maximum inductance or it can be read from the
graph in Figure 7. Once the maximum inductance has been
determined the peak current can be determined using Equa-
tion 3 or the graph in Figure 13.
V
OUT
= 12V
I
OUT
= 5mA
V
IN
= 2.5V to 4.7V
F
max
= 360kHz
= 0.8 = efficiency
D
nom
= 0.55
T
1
F
1
360kHz
2.78 sec
t
D
f
0.55
360kHz
1.53 sec
L
V
t
I
2
T
1
V
V
L
sec
sec
H
S(min)
max
ON(min)
nom
max
max
IN(min)
ON(min)
O(max)
S(min)
O
IN(min)
max
2
=
=
=
=
=
=
-
=
-
=
2
2
2
2 5
1 53
5
2
2 78
1
12
0 8
2 5
42
.
.
.
.
.
mA
Select 39
H
10%.
t
1.1 D
F
1.1 0.55
300kHz
2 sec
I
t
V
L
2.0 sec
4.7V
35 H
270mA
ON(max)
nom
min
peak
ON(max)
IN(max)
min
=
=
=
=
=
=
Bootstrap Configuration
For input voltages below 4.5V the bootstrap configuration can
increase the output power capability of the MIC2142. Figure
2 shows the bootstrap configuration where the output voltage
is used to bias the MIC2142. This impoves the power capa-
bility of the MIC2142 by increasing the gate drive voltage
hence the peak current capability of the internal switch. This
allows the use of a smaller inductor which increases the
output power capability. Table 4 also summarizes the various
configurations and power capabilities using the booststrap
configuration. This bootstrap configuration is limited to output
voltage of 16V or less.
Figure 1 shows how a resistor (R3) can be added to reduce
the ripple seen at the V
CC
pin when in the bootstrap configu-
ration. Reducing the ripple at the V
CC
pin can improve output
ripple in some applications.
R2
36.5k
R1
12.4k
C1
22
F
+5V @80mA
GND
GND
+3.0V to +4.2V
V
IN
L1
33
H
CR1
MBR0530
U1 MIC2142
5
3
2
1
4
FB
SW
GND
VCC
EN
C2
10
F
C3
270pF
C4
1
F
R3
100
Figure 1. Bootstrap V
CC
with V
CC
Low Pass Filter
December 2000
9
MIC2142
MIC2142
Micrel
R2
36.5k
R1
12.4k
C1
22
F
+5V @16mA
GND
GND
V
IN
L1
47
H
CR1
MBR0530
U1 MIC2142
5
3
2
1
4
FB
SW
GND
VCC
EN
C2
10
F
C3
270pF
Figure 2. Booststrap Configuration
Rprogram
82
CR6
LWT673
C1
1
F
25V
CR7
LWT673
CR5
LWT673
C2
10
F
+15V @15mA
GND
GND
PWM
L1
10
H
CR1
MBR0530
U1 MIC2142
5
3
2
1
4
FB
SW
GND
VCC
EN
(from
controller)
V
IN
Figure 3. Series White LED Driver with PWM Dimming Control
Rprogram
82
CR6
LWT673
C1
1
F
25V
CR7
LWT673
CR5
LWT673
C2
10
F
+15V @15mA
GND
GND
DAC
SHTDWN
L1
10
H
CR1
MBR0530
R4
R3
U1 MIC2142
5
3
2
1
4
FB
SW
GND
VCC
EN
V
IN
Figure 4. Series White LED Driver with Analog Dimming Control
For additional predesigned circuits, see Table 4.
MIC2142
Micrel
MIC2142
10
December 2000
R1
120
CR1
LWT673
C1
1
F
25V
C2
10
F
+5.0V @50mA
GND
GND
DAC
EN
L1
10
H
CR3
MBR0530
R4
R3
U1 MIC2142
5
3
2
1
4
FB
SW
GND
VCC
EN
R2
120
CR2
LWT673
R3
120
CR3
LWT673
V
IN
Figure 5. Parallel White LED Driver with Analog Dimming Control
R2
1.8M
R1
120k
C1
1
F
25V
+20V @0.5mA
GND
V
INRTN
L1
10
H
CR1
BAT54HT1
U1 MIC2142
5
3
2
1
4
FB
SW
GND
VCC
EN
C1
1
F
25V
C2
10
F
V
IN
Figure 6. Handheld LCD Supply
December 2000
11
MIC2142
MIC2142
Micrel
Predesigned Circuit Values
V
IN(min)
V
IN(max)
V
OUT
I
OUT(max)
L1
I
PK
@ V
IN(max)
CR1
2.5V
3.0V
3.3V
40mA
47
H
129mA
BAT54
23mA
85
H
74mA
BAT54
10mA
180
H
34VmA
BAT54
2.5V
4.5V
5V
16.5mA
47
H
193mA
BAT54
7.8mA
100
H
91mA
BAT54
boot strapped
51
15
605
MBR0530
boot strapped
77
10
908
MBR
2.5
11.5
12
4.8
47
493
MBR
2.25
100
232
BAT
4.7
boot strapped
15
15
632
MBR
boot strapped
22
10
950
MBR
2.5
14.5
15
3.7
47
622
MBR
1.7
100
292
BAT
4.7
boot strapped
17.4
10
950
MBR
boot strapped
8
22
430
MBR
2.5
4.7
20
2.7
47
202
BAT
2.5
4.7
20
1.5
82
110
BAT
3.0
4.7
5
40
33
287
BAT
boot strapped
70
18
525
MBR
boot strapped
100
12
800
MBR
3.0
8.5
9
15
33
520
MBR
4.7
boot strapped
28
18
525
MBR
4.7
boot strapped
40
12
800
MBR
3.0
14.5
15
7.8
33
886
MBR
3.0
4.7
boot strapped
14
18
525
MBR
3.0
4.7
boot strapped
21
12
800
MBR
3.0
4.7
20
5.6
33
287
BAT
5.0
8.5
9
70
27
635
MBR
23
82
209
BAT
10
180
95
BAT
5.0
11.5
12
43
27
860
MBR
14
82
283
BAT
6
180
129
BAT
5.0
14.5
15
30
27
1083
MBR
10
82
357
MBR
9
30
27
672
MBR
5.0
8.0
20
8
68
237
BAT
9
11.5
12
118
56
414
MBR
66
100
232
BAT
30
220
105
BAT
9
14
15
70
56
504
MBR
40
100
282
BAT
18
220
128
BAT
9
14
20
20
120
235
BAT
10
220
128
BAT
6
390
72
BAT
12
14
15
156
68
415
MBR
71
150
182
BAT
27
390
72
BAT
12
14
20
35
150
188
BAT
Table 4. Typical Maximum Power Configuration
MIC2142
Micrel
MIC2142
12
December 2000
V
OUT
= 16V to 22V
V
OUT
< 16V (boostraped)
V
OUT
< 16 (boostraped)
85C
85C
40C
V
IN
(V)
L
MIN
(
H)
L
MIN
(
H)
L
MIN
(
H)
2.5
47
47 (15)
47 (10)
3
33
33 (18)
33 (12)
3.5
47
27 (22)
27 (15)
4
56
27 (22)
22 (18)
5
68
27
22
6
82
33
22
7
100
39
27
8
100
47
33
9
120
56
33
10
150
56
39
11
150
68
47
12
150
68
47
13
180
82
56
14
180
82
56
15
220
82
56
16
220
100
68
Table 6. Minimum Inductance
Manufacturer
Web Address
MuRata
www.MuRata.com
Sumida
www.sumida.com
Coilcraft
www.coilcraft.com
J. W. Miller
www.jwmiller.com
Micrel
www.micrel.com
Vishay
www.vishay.com
Panasonic
www.panasonic.com
Table 7. Component Supplier Websites
V
N
I
V
T
U
O
I
T
U
O
1
L
1
R
C
I
K
A
E
P
n
o
i
t
a
r
u
g
i
f
n
o
C
%
5
V
3
.
3
V
5
V
9
V
2
1
V
5
1
V
0
2
A
m
0
7
A
m
0
3
A
m
0
2
A
m
5
1
A
m
6
H
8
1
H
8
1
H
8
1
H
8
1
H
3
3
0
3
5
0
R
B
M
0
3
5
0
R
B
M
0
3
5
0
R
B
M
0
3
5
0
R
B
M
4
5
T
A
B
0
0
4
0
0
4
0
0
4
0
0
4
4
1
2
p
a
r
t
s
t
o
o
B
p
a
r
t
s
t
o
o
B
p
a
r
t
s
t
o
o
B
p
a
r
t
s
t
o
o
B
%
5
V
5
V
9
V
2
1
V
5
1
V
0
2
A
m
0
7
A
m
0
4
A
m
0
3
A
m
0
.
8
H
7
2
H
7
2
H
7
2
H
8
6
0
3
5
0
R
B
M
0
3
5
0
R
B
M
0
3
5
0
R
B
M
4
5
T
A
B
0
7
3
0
7
3
0
7
3
8
4
1
%
5
V
2
1
V
5
1
V
0
2
8
5
1
5
3
8
6
0
5
1
0
5
3
0
R
B
M
4
5
T
A
B
0
5
3
0
6
1
%
5
V
5
1
V
0
2
0
5
0
2
2
4
5
T
A
B
0
4
1
1
Table 5. Typical Maximum Power Configurations for Regulated Inputs
December 2000
13
MIC2142
MIC2142
Micrel
Inductor Selection Guides
1
10
100
1000
0
2
4
6
8
10
12
14
16
18
20
22
MAX. OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
12
H
15
H
10
H
220
H
180
H
120
H
100
H
82
H
68
H
56
H
47
H
39
H
33
H
22
H
18
H
V
IN
= 2.5V
150
H
Figure 7. Inductor Selection for V
IN
= 2.5V
1
10
100
1000
0
2
4
6
8
10
12
14
16
18
20
22
24
MAX. OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
12
H
15
H
27
H
220
H
180
H
120
H
100
H
82
H
68
H
56
H
47
H
39
H
33
H
22
H
18
H
V
IN
= 3.0V
150
H
Figure 8. Inductor Selection for V
IN
= 3.0V
MIC2142
Micrel
MIC2142
14
December 2000
1
10
100
1000
2
4
6
8
10
12
14
16
18
20
22
24
MAX. OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
27
H
220
H
180
H
120
H
100
H
82
H
68
H
56
H
47
H
39
H
33
H
22
H
18
H
V
IN
= 5.0V
150
H
Figure 9. Inductor Selection for V
IN
= 5V
1
10
100
1000
8
10
12
14
16
18
20
22
24
MAX. OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
330
H
220
H
180
H
120
H
100
H
82
H
68
H
56
H
47
H
39
H
270
H
390
H
470
H
V
IN
= 9.0V
150
H
Figure 10. Inductor Selection for V
IN
= 9V
December 2000
15
MIC2142
MIC2142
Micrel
1
10
100
1000
10
12
14
16
18
20
22
24
MAX. OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
330
H
220
H
180
H
120
H
100
H
82
H
68
H
56
H
47
H
270
H
390
H
470
H
V
IN
= 12.0V
150
H
Figure 11. Inductor Selection for V
IN
= 12V
10
100
1000
14
16
18
20
22
24
MAX. OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
220
H
180
H
150
H
120
H
100
H
82
H
68
H
56
H
270
H
330
H
390
H
470
H
V
IN
= 15V
Figure 12. Inductor Selection for V
IN
= 15V
MIC2142
Micrel
MIC2142
16
December 2000
0
100
200
300
400
500
600
0
1
2
3
4
5
6
7
8
9
10
11 12 13
14 15
16 17
18 19 20
21 22
PEAK CURRENT (mA)
INPUT VOLTAGE (V)
12
H
18
H
22
H
15
H
220
H
180
H
150
H
120
H
100
H
82
H
56
H
47
H
39
H
33
H
27
H
8.2
H
10
H
16V to 20VOUT Limit
3.5VCC Limit
4.5V to 15VCC Limit
2.5VCC Limit
68
H
Figure 13. Peak Inductor Current vs. Input Voltage
December 2000
17
MIC2142
MIC2142
Micrel
Package Information
0.20 (0.008)
0.09 (0.004)
0.60 (0.024)
0.10 (0.004)
3.02 (0.119)
2.80 (0.110)
10
0
3.00 (0.118)
2.60 (0.102)
1.75 (0.069)
1.50 (0.059)
0.95 (0.037) REF
1.30 (0.051)
0.90 (0.035)
0.15 (0.006)
0.00 (0.000)
DIMENSIONS:
MM (INCH)
0.50 (0.020)
0.35 (0.014)
1.90 (0.075) REF
SOT23-5 (M3)
MICREL INC.
1849 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
2000 Micrel Incorporated
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