Micrel MIC2142 User Manual

MIC2142 Micrel

查询MIC2142供应商

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 85µA, and
a typical shutdown current of 0.1µA. 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

Typical Application

Features

• 2.2V to 16V input voltage

• Up to 22V output voltage

• 330kHz switching frequency

• 0.1µA shutdown current

•85µA 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

2.8V to 4.7V
V

IN

C

IN

10µF

L1

33µH

MIC2142

VCC SW

1

5

FB

GNDEN

D1

3

4

2

R2
365k

R1
124k

Typical Configuration

+5V @60mA

C

OUT

22µF

Efficiency

vs. Output Current

0.90

0.85

0.80

0.75

0.70

0.65

0.60

0.55

EFFICIENCY (%)

0.50

0.45

0.40
0 10203040506070

OUTPUT CURRENT (mA)

VIN = 4.2V

VIN = 3.0V

Efficiency vs. Output Current

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

December 2000 1 MIC2142

MIC2142 Micrel

Ordering Information

Part Number Voltage Ambient Temp. Range Package

MIC2142BM5 Adj –40°C to +85°C SOT23-5

Pin Configuration

VCC

GND

SW

13

2

SBAA

45

FB

SOT23-5 (BM5)

EN

Part
Identification

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 0.1µA typical supply current.

MIC2142 2 December 2000

MIC2142 Micrel

Absolute Maximum Ratings (Note 1)

Supply voltage (VCC).....................................................18V

Switch voltage (V
Enable pin voltage (V
Feedback Voltage (VFB)

Adjustable version.......................................................8V

Ambient Storage Temperature (TS) .........–65°C to +150°C

) ....................................................24V

SW

) Note 3...................................18V

EN

Operating Ratings (Note 2)

Supply Voltage (VCC) ....................................... 2.2V to 16V

Enable pin voltage (V
Switch Voltage (V

Ambient Temperature (TA).........................–40°C to +85°C

Junction Temperature Range (T
Package Thermal Impedance

θ

SOT23-5 .....................................................220°C/W

JA

) Note 3......................... 0V to 16V

EN

)....................................................22V

SW

) ...........–40°C to +125°C

J

Electrical Characteristics

VCC =3.6V, V

Parameter Condition Min Typ Max Units

Input Voltage 2.2 16 V
Quiescent Current VEN = ON , VFB = 2.2V 85 125 µA

Feedback Voltage (VFB)(±2%) 1.254 1.28 1.306 V

Comparator Hysteresis 18 mV
Feedback Input Bias Current 30 nA

Note 4

Enable Input Voltage VIH (turn on) 0.6VCC0.55V

Enable Input Current –1 0.01 1 µA
Load Regulation 200µA ≤ I
Line Regulation 2.2V ≤ VCC ≤ 16V; I
SW on Resistance ISW = 100mA, VCC = 2.5V 5 Ω

Switch Leakage Current VEN = OFF, VSW = 12V 0.05 1 µA
Oscillator Frequency 295 330 365 kHz
Duty Cycle 50 57 65 %

OUT

= 5V, I

= 20mA, TA=25°C; unless otherwise specified. Bold values indicate 25°C ≤ TJ ≤ 125°C.

OUT

VEN = OFF (shutdown) 0.1 2 µA

(±3%) 1.241 1.312 V

VIL (turn off) 1.1 0.8 V

≤ 20mA 0.2 %V

OUT

= 4mA 0.25 %/V

OUT

ISW = 100mA, VCC = 12V 2 Ω

CC

V

OUT

Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when

Note 2: The device is not guaranteed to function outside its operating rating.
Note 3: VEN must be ≤ V
Note 4: The maximum suggested value of the programming resistor, whose series resistance is measured from feedback to ground, is 124kΩ. Use of

Note 5: Devices are ESD sensitive, handling precautions required.

operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction
temperature, T
dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The θJA of the power SOT23-5 is 220°C/W
mounted on a PC board.

larger resistor values can cause errors in the output voltage due to the feedback input bias current.

, the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power

J(Max)

IN

December 2000 3 MIC2142

MIC2142 Micrel

µ

g

Typical Characteristics

Quiescent Current

vs. Input Voltage

350

V

= 5V

OUT

300
250
200
150
100

50

QUIESCENT CURENT (µA)

0

0 2 4 6 8 10 12 14 16

INPUT VOLTAGE (V)

Output Ripple

1200

1000

OUTPUT RIPPLE (mV)

vs. Input Voltage

IL = 7mA
L = 22

H

800

600

V

= 15V

OUT

400

200

0

02468101214

INPUT VOLTAGE (V)

IL = 2mA
L = 220µH

VDS and R

vs. Input Voltage

600

500

400

(V)

300

DS

V

200

100

0

0 2 4 6 8 10 12 14

INPUT VOLTAGE (V)

DS(ON)

ISW= 100mA

Efficiency

vs. Input Voltage

85

80

75

IL = 7mA
L = 22µH

70

EFFICIENCY (%)

65

V

= 15V

OUT

60

2 4 6 8 101214

INPUT VOLTAGE (V)

IL = 2mA
L = 220µH

6

5

4

3

DS(ON)

R

2

1

0

16.5

15.5

14.5

OUTPUT VOLTAGE (V)

OUTPUT VOLTAGE (V)

Line Regulation

I

= 7mA

L

L = 22µH

16

IL= 2mA
L = 220µH

15

14

2 4 6 8 10 12 14

INPUT VOLTAGE (V)

MIC2142 Load

ulation

16
14
12
10

8
6
4
2
0

0 5 10 15 20 25 30

Re

L = 22µH
VIN = 5V

OUTPUT CURRENT (mA)

V

V

OUT

REF

Oscillator Characteristics

350
300
250
200
150
100

FREQUENCY (kHz)

vs. Input Voltage

Frequency

Duty Cycle

VO = 15V
I

= 100µA

O

50

L= 220µH

0

02468101214

INPUT VOLTAGE (V)

tON vs.

2

1.9

1.8

1.7

1.6

1.5

(µsec)

1.4

ON

t

1.3

1.2

1.1
1

-50 -30 -10 10 30 50 70 90 110

Temperature

TEMPERATURE (°C)

0.65

0.60

0.55

0.50

0.45

0.40

DUTY CYCLE

Quiescent Current

vs. Temperature

84
82
80
78
76
74
72

QUIESCENT CURRENT (µA)

70

-50 -30 -10 10 30 50 70 90 110

TEMPERATURE (°C)

Frequency vs.

340
335
330
325
320
315
310
305

FREQUENCY (kHz)

300
295

-50 -30 -10 10 30 50 70 90 110

Temperature

TEMPERATURE (°C)

VIN = 3.6V

V

and V

OUT

15.20

15.15

15.10

15.05

15.00

14.95

OUTPUT VOLTAGE (V)

14.90

Over Temperature

V

=

3.6V

IN

I

= 100µA

O

L = 22µH

V

OUT

V

REF

-50 -30 -10 10 30 50 70 90 110

TEMPERATURE (°C)

Timing Characteristics

Over Temperature

3.5

3.0

T (µsec)

2.5

2.0

1.5

tON (µsec)

1.0

0.5
Duty Cycle

0

OSCILLATOR CHARACTERISTICS

-50 -30 -10 10 30 50 70 90 110

TEMPERATURE (°C)

REF

1.290

1.285

1.280

1.275

REFERENCE VOLTAGE (V)

1.270

MIC2142 4 December 2000

MIC2142 Micrel

R

vs.

DS(ON)

Temperature

7
6
5

(Ω)

4
3

DS(ON)

R

2
1
0

-50 -30 -10 10 30 50 70 90 110

VCC=3.3V

VCC = 4.5V

TEMPERATURE (°C)

Timing Characteristics

Over Temperature

0.6

0.58

0.56

0.54

0.52

0.5

0.48

0.46

DUTY CYCLE (%)

0.44

0.42

0.4

-50 -30 -10 10 30 50 70 90 110

TEMPERATURE (°C)

December 2000 5 MIC2142

MIC2142 Micrel

Functional Diagram

EN

FB

Bandgap

Reference

Shutdown

MIC2142

VCC

Oscillator

330kHz

FIXED DUTY CYCLE

SW

GND

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 85µA in the switch
off state, and since a MOSFET output switch is used, addi­tional 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
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

input. An external resistive

REF

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 capa­bility of the output switch. Output voltages up to 22V can be
achieved with a standard boost circuit. Higher output volt­ages can be realized with a flyback configuration.

MIC2142 6 December 2000

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 2MΩ limits the additional load
on the output to 20µA 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.

R1 R2

+

(1)

V

OUT



=





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 maxi­mum inductor value. The largest inductor possible is prefer­able 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.

()

=

tV

ON max IN max

()()

=

(2)

(3)

I

O(max)

I

PK

Table 1 lists common inductors suitable for most applica­tions. Due to the internal transistor peak current limitation at
low input voltages, inductor values less than 10µH are not



V



REF



R1

Vt

IN(min)

2L T

MAX

L

MIN

2

ON

S

V

eff

1

O

V

−

IN min

()

×

recommmended. Table 6 lists minimum inductor sizes versus
input and output voltage. In low-cost, low-peak-current appli­cations, RF-type leaded inductors may sufficient. All induc­tors listed in Table 5 can be found within the selection of
CR32- or LQH4C-series inductors from either Sumida or
muRata.

rerutcafunaMseireSepyTeciveD

ataRuMC4/C3/C1HQLtnuomecafrus
adimuS23RCtnuomecafrus

relliM.W.JF87dedaellaixa

tfarclioC09dedaellaixa

Table 1. Inductor Examples

Boost Output Diode

Speed, forward voltage, and reverse current are very impor­tant 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” respec­tively. They are suitable for peak repetitive currents of 300mA
or less with good reverse current characteristics. For applica­tions 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.

57C°

V

edoiD

0350RBMV572.0V523.0Aµ5.2Aµ09

8414N1

45TAB

58TAB

DWF

ta

Am001

V6.0

V4.0

45.0

C°52

V

DWF

ta

Am001

V59.0

)C°571(

)C°58(

)C°58(

V54.0

V65.0Aµ4.0

mooR

.pmeT

egakaeL

V51ta

An52

)V02(

An01

)V52(

C°57

egakaeL

V51ta

Aµ2.0

)V02(

Aµ1

)V02(

Aµ2

)C5°8(

egakcaP

321DOS

TMS

dedael

TMSdna

TMS

43-OD
dedael

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 capaci­tor from Panasonic. In general, ceramic, electrolytic, or
tantalum values ranging from 1µF to 22µF can be used for the
output capacitor.

December 2000 7 MIC2142

MIC2142 Micrel

rerutcafunaMseireSepyTegakcaP

ataRuMMRGV5Ycimarectnuomecafrus

yahsiV495mulatnattnuomecafrus

cinosanaPseires-Mcitylortcelededael

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 Equa­tion 3 or the graph in Figure 13.

V

= 12V

OUT

I

= 5mA

OUT

VIN = 2.5V to 4.7V
F

= 360kHz

max

η = 0.8 = efficiency
D

= 0.55

nom

T

S(min)

t

ON(min)

L

max

L

max

1

== =µ

F

max

D

nom

== µ

f

max

Vt

IN(min)

=

I2T

O(max) S(min)

2

25 153

..

=

52278

mA

×× µ

1

360kHz

0.55

360kHz

22

×

ON(min)

××

2.78 sec

1.53 sec

×

V

O

η

2

×µ

sec

×

12

sec

.

08

.

−

1

−

1

V

IN(min)

25

.

H

42

=µ

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 capa­bility 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

pin when in the bootstrap configu-

CC

ration. Reducing the ripple at the VCC pin can improve output
ripple in some applications.

+3.0V to +4.2V

V

IN

C2

10µF

L1

33µH

U1 MIC2142

FB SW

4

5

GND

VCCEN

CR1

MBR0530

3

2

1

100

C4
1µF

R3

R2

36.5k

R1

12.4k

C1
22µF

+5V @80mA

C3
270pF

GNDGND

Figure 1. Bootstrap VCC with VCC Low Pass Filter

Select 39µH ±10%.

t

ON(max)

I

peak

1.1 D

=

tV

ON(max)

=

F

×

L

min

min

nom

×

1.1 0.55

=

IN(max)

×

300kHz

µ×

2.0 sec 4.7V

=

35 H

=µ

2 sec

µ

=

270mA

MIC2142 8 December 2000

MIC2142 Micrel

L1

V

IN

47µH

CR1

MBR0530

+5V @16mA

For additional predesigned circuits, see Table 4.

V

C2

10µF

U1 MIC2142

FB SW

4

GND

VCCEN

5

3

2

1

Figure 2. Booststrap Configuration

L1

10µH

IN

CR1

MBR0530

R2

36.5k

R1

12.4k

C1
22µF

C3
270pF

GNDGND

CR5
LWT673

CR7
LWT673

+15V @15mA

(from µcontroller)

PWM

C2

10µF

U1 MIC2142

FB SW

4

GND

VCCEN

5

3

2

1

C1
1µF
25V

Rprogram

82Ω

CR6
LWT673

GNDGND

Figure 3. Series White LED Driver with PWM Dimming Control

V

SHTDWN

L1

10µH

IN

U1 MIC2142

FB SW

4

10µF

C2

GND
VCCEN

5

CR1

MBR0530

3

2

1

C1
1µF
25V

CR5
LWT673

CR7
LWT673

CR6
LWT673

Rprogram
82Ω

+15V @15mA

GNDGND

DAC

R4 R3

Figure 4. Series White LED Driver with Analog Dimming Control

December 2000 9 MIC2142

MIC2142 Micrel

L1

V

IN

10µH

CR3

MBR0530

+5.0V @50mA

EN

GND

DAC

C2

10µF

R4 R3

U1 MIC2142

FB SW

4

GND

VCC EN

5

3

2

1

C1
1µF
25V

CR1
LWT673

R1
120Ω

CR2
LWT673

R2
120Ω

Figure 5. Parallel White LED Driver with Analog Dimming Control

V

IN

C2

10µF

L1

10µH

U1 MIC2142

FB SW

4

5

GND

VCCEN

CR1

BAT54HT1

3

2

1

C1
1µF
25V

R2

1.8M

R1
120k

+20V @0.5mA

C1
1µF
25V

CR3
LWT673

R3
120Ω

GND

INRTN

GNDV

Figure 6. Handheld LCD Supply

MIC2142 10 December 2000

MIC2142 Micrel

Predesigned Circuit Values

V

IN(min)

V

IN(max)

V

OUT

I

OUT(max)

L1 IPK @ V

IN(max)

CR1

2.5V 3.0V 3.3V 40mA 47µH 129mA BAT54
23mA 85µH 74mA BAT54
10mA 180µH 34VmA BAT54

2.5V 4.5V 5V 16.5mA 47µH 193mA BAT54

7.8mA 100µH 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

December 2000 11 MIC2142

MIC2142 Micrel

V

NI

%5±V3.3V5

%5±V5V9

%5±V21V51

V

TUO

V9

V21
V51
V02

V21
V51
V02

V02

I

TUO

Am07

Am03
Am02

Am51

Am6

Am07

Am04
Am03

Am0.8

851

53

1L1RCI

Hµ81
Hµ81
Hµ81
Hµ81

Hµ33
Hµ72

Hµ72
Hµ72
Hµ86

86

051

0350RBM
0350RBM
0350RBM
0350RBM

45TAB

0350RBM
0350RBM
0350RBM

45TAB

0530RBM

45TAB

KAEP

004
004
004
004

partstooB
partstooB
partstooB
partstooB

412
073

073
073
841

053
061

%5±V51V020502245TAB0411

Table 5. Typical Maximum Power Configurations for Regulated Inputs

V

= 16V to 22V V

OUT

85C 85C 40C

VIN (V) L

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)
568 27 22
682 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

(µH) L

MIN

< 16V (boostraped) V

OUT

(µH) L

MIN

< 16 (boostraped)

OUT

(µH)

MIN

Table 6. Minimum Inductance

noitarugifnoC

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

MIC2142 12 December 2000

MIC2142 Micrel

Inductor Selection Guides

1000

10µH

12µH
15µH

18µH

100

22µH

33µH

39µH
47µH

56µH

68µH

82µH

100µH
120µH

MAX. OUTPUT CURRENT (mA)

150µ
H
180µH

10

220µH

VIN = 2.5V

1000

12µH
15µH

18µH
22µH
27µH

33µH
39µH

100

47µH
56µH

68µH

82µH
100µH
120µH

150µH

180µH
220µH

MAX. OUTPUT CURRENT (mA)

10

VIN = 3.0V

1

0246810121416182022

OUTPUT VOLTAGE (V)

Figure 7. Inductor Selection for VIN = 2.5V

1

0 2 4 6 8 1012141618202224

OUTPUT VOLTAGE (V)

Figure 8. Inductor Selection for VIN = 3.0V

December 2000 13 MIC2142

MIC2142 Micrel

1000

18µH
22µH
27µH
33µH

39µH
47µH
56µH
68µH
82µH

100µH

100

120µH
150µH

180µH
220µH

MAX. OUTPUT CURRENT (mA)

10

VIN = 5.0V

1000

39µH
47µH
56µH
68µH
82µH

100µH

100

120µH
150µH

180µH

220µH

270µH

330µH
390µH
470µH

MAX. OUTPUT CURRENT (mA)

10

VIN = 9.0V

1

24681012141618202224

Figure 9. Inductor Selection for V

OUTPUT VOLTAGE (V)

IN

= 5V

1

8 1012141618202224

OUTPUT VOLTAGE (V)

Figure 10. Inductor Selection for VIN = 9V

MIC2142 14 December 2000

MIC2142 Micrel

)

1000

47µH
56µH

68µH

82µH
100µH
120µH

150µH
180µH
220µH

270µH

100

330µH
390µH

470µH

MAX. OUTPUT CURRENT (mA)

10

VIN = 12.0V

1000

100

MAX. OUTPUT CURRENT (mA)

VIN = 15V

56µH

68µH

82µH

100µH
120µH

150µH
180µH

1

10 12 14 16 18 20 22 24

OUTPUT VOLTAGE (V)

Figure 11. Inductor Selection for VIN = 12V

220µH

270µH

330µH
390µH

470µH

10

14 16 18 20 22 24

OUTPUT VOLTAGE (V

Figure 12. Inductor Selection for VIN = 15V

December 2000 15 MIC2142

MIC2142 Micrel

600

500

400

300

PEAK CURRENT (mA)

200

10µH

12µH

15µH

18µH

27µH

22µH

39µH

33µH

47µH

56µH

68µH

82µH

4.5V to 15VCC Limit

100µH

120µH

150µH

3.5VCC Limit

180µH

220µH

100

0

0 1 2 3 4 5 6 7 8 9 10111213141516171819202122

INPUT VOLTAGE (V)

Figure 13. Peak Inductor Current vs. Input Voltage

16V to 20VOUT Limit

8.2µH

2.5VCC Limit

MIC2142 16 December 2000

MIC2142 Micrel

Package Information

1.90 (0.075) REF

0.95 (0.037) REF

3.02 (0.119)

2.80 (0.110)

0.50 (0.020)

0.35 (0.014)

1.75 (0.069)

1.50 (0.059)

1.30 (0.051)

0.90 (0.035)

0.15 (0.006)

0.00 (0.000)

SOT23-5 (M3)

3.00 (0.118)

2.60 (0.102)

10°

0°

DIMENSIONS:

MM (INCH)

0.20 (0.008)

0.09 (0.004)

0.60 (0.024)

0.10 (0.004)

MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 [phone] FAX + 1 [phone] 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

December 2000 17 MIC2142