Micrel MIC2145 User Manual

MIC2145 Micrel

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MIC2145

High Efficiency 2.5W Boost Converter

Final

General Description

The MIC2145 is a small size boost switching regulator that
can provide over 2.5W of output power. The input voltage
range is between 2.4V 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 MIC2145 can be adjusted up
to 16V.

The MIC2145 is well suited for portable, space-sensitive
applications. Its typical 450kHz operation allows small sur­face mount external components to be used. The MIC2145
has a low quiescent current of 200µA, and a typical shutdown
current of 0.5µA. The MIC2145 is capable of high efficiencies
in a small board area.

The MIC2145 features a low-on resistance internal switch
that allows it to provide over 2.5W of output power. The peak
switch current can be programmed through an external
resistor. This allows the user to set the peak switch current at
the level where maximum efficiency occurs. It also allows the
user to further optimize for efficiency and inductor size by
setting the peak current below the level of inductor saturation.

The MIC2145 is available in an MSOP-8 and 3mm×3mm
MLF™-10L package with an ambient operating temperature
range from –40°C to +85°C.

Ordering Information

Features

• 2.4V to 16V input voltage

• Output adjustable to 16V

• Programmable peak current limit

• Soft start

• Up to 450kHz switching frequency

• 0.5µA shutdown current

• 200µA quiescent current

• Capable of 5V/ 500mA output with 3.3V input

• Achieves over 85% efficiency

• Implements low power BOOST, SEPIC, and FLYBACK

topologies

• MSOP-8 and 3mm×3mm MLF™-10L

Applications

• Flash LED driver

• LCD bias supply

• White LED driver

• DSL bias supply

• Local 3V to 5V conversion

T ypical Application

V

3.0V to 5.0V

IN

C

IN

10 F/6.3V

Adjustable Output Boost Converter with Programmable Peak Switch Current

I Limit

Part Number Voltage Ambient Temp. Range Package

MIC2145BMM Adj –40°C to +85°C 8-lead MSOP
MIC2145BML Adj –40°C to +85°C3×3 MLF™-10L

L1

10 H

15

EN SW

4

PGND

MIC2145BMM

3

RSET

2

SS

VDD

SGND

FB

D1

6

7

8

V

OUT

10V/150mA

C

OUT

10 F/16V

10V Output

90

85

80

75

70

EFFICIENCY (%)

65

60

10 100 1000

Efficienc

VIN = 3.0V

OUTPUT CURRENT (mA)

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

May 2003 1 MIC2145

MIC2145 Micrel

Pin Configuration

SS

RSET

PGND

1EN
2
3
4

8 SGND

FB

7

VDD

6

SW

5

8-Lead MSOP (MM)

Pin Description

Pin Number Pin Number Pin Name Pin Function

MSOP MLF

1 1 EN Enable (Input): Logic high (≥1.5V) enables regulator. Logic low (≤0.7V)

shuts down regulator. Do not float.

2 2 SS Soft Start Capacitor (External Component): Connect external capacitor to

ground to control the rise time of the output voltage.

3 3 RSET Current Limit (External Component): Sets peak current limit of the internal

power MOSFET using an external resistor.
4 4, 5 PGND Power Ground (Return): Internal power MOSFET source.
5 6, 7 SW Switch Node (Input): Internal power MOSFET drain.
6 8 VDD Supply (Input): +2.4V to +16V for internal circuitry.
7 9 FB Feedback (Input): Output voltage sense node.
8 10 SGND Small Signal Ground (Return): Ground

EN

1

SS

2

RSET

PGND
PGND SW

3
4
56

××

3mm

×3mm MLF-10L (ML)

××

10

9
8
7

SGND
FB
VDD
SW

MIC2145 2 May 2003

MIC2145 Micrel

Absolute Maximum Ratings (Note 1)

Supply Voltage (V
Switch Voltage (V
Feedback Voltage (V

Switch Current (ISW) ........................................................2A

Enable Voltage(V
RSET Voltage (V

ESD Rating, Note 3 ......................................................2kV

Ambient Storage Temperature(T

) ....................................................18V

DD

) ....................................................18V

SW

) ................................................18V

FB

), Note 5 ........................................18V

EN

)....................................................6V

RSET

) ..........–65°C to +150°C

S

Operating Ratings (Note 2)

Supply Voltage (V
Switch Voltage (V
Ambient Temperature (T

Junction Temperature (TJ) ....................... –40°C to +125°C

Package Thermal Resistance MSOP

(MSOP-8) ....................................................206°C/W

θ

JA

θJA (3mm×3mm MLF-10) ....................................60°C/W

) ....................................... 2.4V to 16V

DD

)....................................................16V

SW

)......................... –40°C to +85°C

A

Electrical Characteristics (Note 6)

VDD = 10V, V

Parameter Condition Min Typ Max Units

Supply Voltage 2.4 16 V
Shutdown Current EN = 0.3V, VDD = 10V, VFB=1.35V 0.5 5 µA
Quiescent Current EN = VDD, VDD = 10V, VFB = 1.35V 200 300 µA
Feedback Voltage Reference (±2%) 1.058 1.08 1.102 V

Comparator Hysteresis 18 mV
Feedback Input Current VFB=1.35V 40 nA
Peak Current Limit R

Current Limit Comparator 500 ns
Propagation Delay

Switch On-Resistance ISW = 150mA, VDD = 3.0V 500 750 mΩ

Maximum Off Time 1000 ns
Enable Input Voltage Logic Low (turn-off) 1.1 0.7 V

Enable Input Current VEN = 0V –1 0.01 1 µA

Soft Start Current VEN = 2V, VDD=3.0V –8 –12 –16 µA

OUT

= 10V, I

= 100mA; TJ =25°C, unless otherwise noted, bold values indicate –40°C ≤ TJ ≤ 125°C.

OUT

(±3%) 1.048 1.112 V

=200Ω, VDD = 3.6V, Note 4 0.8 A

SET

R

=1kΩ, VDD = 10V, Note 4 0.9 A

SET

ISW = 1.2A, VDD = 10V 250 400 mΩ

Logic High (turn-on) 1.5 1.1 V

VEN = 2V –1 0.01 1 µA

Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5KΩ in series with 100pF.
Note 4. The current is measured in a DC mode. Actual peak switching current will be higher due to internal propagation delay of the circuit.
Note 5. VEN ≤ VDD.
Note 6. Specification for packaged product only.

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MIC2145 Micrel

)

)

)

Typical Characteristics

Efficiency-Basic

100

90

80

70

EFFICIENCY (%)

60

50

16.0

15.8

15.6

15.4

15.2

(V)

15.0

OUT

14.8

V

14.6

14.4

14.2

14.0

Configuration

VIN = 3.3V
V

OUT

L = 10µH

0

0.01

0.02

0.03

0.04

OUTPUT CURRENT (A

0.05

Line Regulation

I

= 10mA

OUT

L = 10µH

246810121416

VDD (V)

= 10V

0.06

0.07

0.08

Efficiency-Bootstrapped

100

90

80

70

EFFICIENCY (%)

60

50

Configuration

0

0.01

0.02

0.03

OUTPUT CURRENT (A

0.04

V
V
L

IN
OUT

=

0.05

Switch On-Resistance

vs. V

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

SWITCH ON-RESISTANCE (Ω)

0.0
0 2 4 6 8 10 12 14 16 18

DD

VDD (V)

3.3V

=

=

10µH

0.06

10V

0.07

0.08

Load Regulation

9.8

9.6

9.4

9.2

0

0.01

0.02

OUTPUT CURRENT (A

0.03

0.04

VIN = 3.6V
L = 10µH

0.05

(V)

OUT

V

10.2

10.0

Switch On-Resistance

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

SWITCH ON-RESISTANCE (Ω)

0.0

vs. Temperature

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

0.06

0.07

0.08

0.09

Quiescent Current

vs. V

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

QUIESCENT CURRENT (Ω)

0.00
0 2 4 6 8 10 12 14 16 18

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

OFF TIME (µs)

0.7

0.6

0.5

vs. Temperature

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

DD

VDD (V)

Off Time

Feedback Voltage

1.1

1.09

1.08

1.07

1.06

FEEDBACK VOLTAGE (V)

1.05

vs. Temperature

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Shutdown Current

vs. Temperature

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

SHUTDOWN CURRENT (µA)

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00

Feedback Current

vs. Temperature

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

FEEDBACK CURRENT (µA)

0.10

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0.00

Quiescent Current

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

QUIESCENT CURRENT (mA)

0.00

vs. Temperature

VIN = 3.6V

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

MIC2145 4 May 2003

MIC2145 Micrel

400

600

800

1000

1200

1400

1600

1800

2000

100 1000 10000 100000

PEAK CURRENT LIMIT (mA)

RSET(Ω)

Peak Current Limit

vs. RSET

15V

5.0V

4.2V

2.4V

3.0V

3.3V

3.6V

8.0V

10V

12V

VOUT/VIN > 1.25

L = 10µH

VIN =

Soft Start Current

vs. Temperature

14
12
10

8
6
4
2

SOFT START CURRENT (µA)

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

VIN = 3.6V

Peak Current Limit

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

PEAK CURRENT LIMIT (A)

0.1

vs. Temperature

R

= 200

SET

R

= 500

SET

VIN = 3.6V
V

= 10V

OUT

L = 10µH

0

-40 -20 0 20 40 60 80 100

R

SET

R

= 10k

SET

TEMPERATURE (°C)

= 1k

May 2003 5 MIC2145