MIC2605YMLTR - Micrel, Inc.

MIC2605/6

0.5A, 1.2MHz / 2MHz Wide Input Range

Boost Regulator with Integrated Switch

and Schottky Diode

MLF and MicroLeadFrame are registered 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

August 2008 M9999-080108-B

General Description

The MIC2605/6 is a 1.2MHz/2MHz, PWM DC/DC boost

switching regulator available in a 2mm x 2mm MLF®

package. High power density is achieved with the

MIC2605/6’s internal 40V/0.5A switch and schottky diode,

allowing it to power large loads in a tiny footprint.

The MIC2605/6 implements constant frequency

1.2MHz/2MHz PWM current mode control. The MIC2605/6

offers internal compensation that offers excellent transient

response and output regulation performance. The high

frequency operation saves board space by allowing small,

low-profile external components. The fixed frequency

PWM scheme also reduces spurious switching noise and

ripple to the input power source.

The MIC2605/6 is available in an 8-pin 2mm x 2mm MLF®

leadless package. This package has an output over-

voltage protection feature.

The MIC2605/6 has an operating junction temperature

range of –40°C to +125°C.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Features

• Wide input voltage range: 4.5V to 20V

• Output voltage adjustable to 40V

• 0.5A switch current and schottky diode

• MIC2605 operates at 1.2MHz

• MIC2606 operates at 2MHz

• Programmable soft start

• Stable with small size ceramic capacitors

• High efficiency

• Low input and output ripple

• <10µA shutdown current

• UVLO

• Output over-voltage and over-temperature protection

• 8-pin 2mm x 2mm MLF® package

• –40°C to +125°C junction temperature range

Applications

• TV-tuners

• Broadband communications

• TFT-LCD bias supplies

• Bias supply

• Positive output regulators

• SEPIC converters

• DSL applications

• Local boost regulators

___________________________________________________________________________________________________________

Typical Application

10µH

499

12.4K

MIC2605/6

VIN

VIN = 12V

VOUT

32V, 30mA

PGND

1µF 1µF

OUT

0.1µF

VDD

0.1µF

20 40 60 80 100 120

LOAD CURRENT (mA)

OUT Efficienc

VIN = 12V

Micrel, Inc. MIC2605/6

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Ordering Information

Part Number Marking

Code(1) Frequency Output Over

Voltage Protection Temperature Range Package(2) Lead Finish

MIC2605YML WZ5 1.2MHz 40V –40° to +125°C 8-Pin 2mm x 2mm MLF® Pb-Free

MIC2606YML WZ6 2MHz 40V –40° to +125°C 8-Pin 2mm x 2mm MLF® Pb-Free

Notes

1. Overbar ( ) symbol my not be to scale.

2. MLF® is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.

Pin Configur ation

VOUT

VIN

VDD

PGND

8-Pin 2mm x 2mm MLF® (ML)

Pin Description

Pin Number Pin Name Pin Function

1 VOUT Output Pin: Connect to the output capacitor.

2 VIN Supply (Input): 4.5V to 20V input voltage.

3 VDD Internal regulated supply. VDD should be connected to VIN when VIN  7V.

4 EN Enable (Input): Logic high enables regulator. Logic low shuts down regulator.

5 SS Soft start

6 FB Feedback (Input): 1.25V output voltage sense node. VOUT = 1.25V (1 + R1/R2).

7 SW Switch Node (Input): Internal power BIPOLAR collector.

8 PGND Power ground

EP EPAD Exposed backside pad for thermal cooling.

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Absolute Maximum Ratings(1)

Supply Voltage (VIN).......................................................22V

Switch Voltage (VSW)....................................... –0.3V to 40V

Enable Voltage (VEN)......................................... –0.3V to VIN

FB Voltage (VFB)............................................................. VDD

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

ESD Rating(3) (MIC2605)................................................ 2kV

ESD Rating(3) (MIC2606)............................................. 1.5kV

Operating Ratings(2)

Supply Voltage (VIN).......................................... 4.5V to 20V

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

Junction Thermal Resistance

2mm x 2mm MLF-8 (θJC) ...................................90°C/W

Electrical Characteristics(4)

TA = 25°C, VIN = VEN = 12V; unless otherwise noted. Bold values indicate –40°C  TJ  +125°C.

Symbol Parameter Condition Min Typ Max Units

VIN Input Voltage Range 4.5 20 V

VDD Internal Regulated Voltage Note 5 5.8 V

VULVO Under-voltage Lockout For VDD 1.8 2.1 2.4 V

IQ Quiescent Current VFB = 2V (not switching) 4.2 6 mA

ISD Shutdown Current VEN = 0V, Note 6 0.1 10 µA

(±2%) 1.225 1.25 1.275 V VFB Feedback Voltage

(±3%) (over temperature) 1.212 1.288 V

IFB Feedback Input Current VFB = 1.25V –550 nA

Line Regulation 8V  VIN  14V, VOUT = 18V 0.04 1 %

Load Regulation 5mA  IOUT  40mA, VOUT = 18V, Note 7 1.5 %

DMAX Maximum Duty Cycle MIC2605

MIC2606

ISW Switch Current Limit Note 7 0.5 0.8 A

VSW Switch Saturation Voltage ISW = 0.5A 600 mV

ISW Switch Leakage Current VEN = 0V, VSW = 18V 0.01 5 µA

VEN Enable Threshold Turn ON

Turn OFF

1.5

0.3

IEN Enable Pin Current VEN = 12V 20 40 µA

Oscillator Frequency (MIC2605) 1.02 1.2 1.38 MHz fSW

Oscillator Frequency (MIC2606) 1.7 2 2.3 MHz

VD Schottky Forward Drop ID = 1mA

ID = 150mA

450

850

IRD Schottky Leakage Current VR = 30V 0.1 4 µA

VOVP Output Over-voltage Protection 15% Over programmed VOUT 10 15 20 %

150 °C TJ Over-temperature Threshold

Shutdown Hysteresis 10 °C

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, TJ(Max), the

junction-to-ambient thermal resistance, θ JA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive die

temperature, and the regulator will go into thermal shutdown.

2. The device is not guaranteed to function outside its operating rating.

3. IC devices are inherently ESD sensitive. Handling precautions required. Human body model rating: 1.5k in series with 100pF.

4. Specification for packaged product only.

5. Connect VDD pin to VIN pin when VIN  7V.

6. ISD = IVIN.

7. Guaranteed by design.

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Typical Characteristics

1.0

1.2

1.4

1.6

1.8

2.0

4 6 8 10 12 14 16 18

INPUT VOLTAGE (V)

Frequency

vs. Input Voltage

MIC2606

MIC2605

1 3 5 7 9 11 13 15 17 19

INPUT VOLTAGE (V)

Quiescent Curren t

vs. Input Voltage

No Switching FB Pin @ 2V

4 6 8 10 12 14 16 18 20

INPUT VOLTAGE (V)

Max Duty Cycle

vs. Inp u t Voltage

EN = VIN

100

200

300

400

500

600

700

800

900

1000

1100

4 6 8 10 12 14 16 18 20

INPUT VOLTAGE (V)

Switch Saturatio n Vo ltag e

vs. Input Voltage

–50mA –0.1A –0.15A –0.2A

–0.25A –0.3A –0.35A –0.4A

–0.45A –0.5A –0.55A –0.6A

–0.65A –0.7A –0.75A –0.8A

–0.85A

100

200

300

400

500

600

700

800

900

1000

1100

SWITCH CURRENT (mA)

Switch Saturatio n Vo ltag e

vs. Switch Curren t

–4.5V –5V –6V –7V –8V –9V

–10V –11V –12V –15V –20

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

4 6 8 10 12 14 16 18 20

INPUT VOLTAGE (V)

Switch Current Limit

vs. Inp u t Voltage

EN = VIN

32.8

32.9

33.0

33.1

33.2

33.3

33.4

4 6 8 10 12 14 16 18

INPUT VOLTAGE (V)

Line Regulation

Load = 40mA

4 8 12 16 20 24 28 32 36 40

LOAD CURRENT (mA)

32VOUT Efficiency

12VIN

4.5VIN

20 40 60 80 100 120

LOAD CURRENT (mA)

32VOUT Efficiency

VIN = 12V

1.250

1.252

1.254

1.256

1.258

1.260

1.262

1.264

1.266

Feedback Volta ge

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

Load = 100mA

0.70

0.75

0.80

0.85

0.90

0.95

1.00

Switch Current Lim it

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

100

1000

VSAT

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

ISW=400mA

ISW=100mA

ISW=750mA

Micrel, Inc. MIC2605/6

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Typical Characteristics (c ontinued)

1.240

1.245

1.250

1.255

1.260

1.265

1.270

Enable T hr esh ol d O N

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

100

Max Duty Cycle

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

1.0

1.2

1.4

1.6

1.8

2.0

Frequency

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

MIC2606

MIC2605

Enable Cu r rent

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

0.065

0.070

0.075

0.080

0.085

0.090

0.095

0.100

Shutdown Current

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

4.10

4.12

4.14

4.16

4.18

4.20

4.22

4.24

4.26

4.28

4.30

Quiescent Current

vs. Temperatur e

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

100

150

200

250

300

350

400

Thermal Derating

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

VIN = 12V

VOUT = 18V

Micrel, Inc. MIC2605/6

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Functional Characteristics

Micrel, Inc. MIC2605/6

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Functional Diagram

PGND

OVP

THERMAL

UVLO

BANDGAP

Ramp

Generator

1.2/2MHz

Oscillator

VDD

VIN

1.25V

PWM

CMP

OVP CMP

Regulator

Bandgap

OSC

5.8V

VOUT

Figure 1. MIC2605/6 Block Diagram

Micrel, Inc. MIC2605/6

August 2008 8 M9999-080108-B

Functional Description

The MIC2605/6 is a constant frequency, PWM current

mode boost regulator. The block diagram is shown in

Figure 1. The MIC2605/6 is composed of an oscillator,

slope compensation ramp generator, current amplifier,

gm error amplifier, PWM generator, and a 0.5A bipolar

output transistor. The oscillator generates a 1.2MHz/

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 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.

The gm error amplifier measures the feedback voltage

through the external feedback resistors and amplifies the

error between the detected signal and the 1.25V

reference voltage. The output of the gm 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,

maintaining the constant frequency current-mode PWM

control.

Pin Description

VIN

VIN provides power to the MOSFETs for the switch

mode regulator section. Due to the high switching

speeds, a 1µF capacitor is recommended close to VIN

and the power ground (PGND) pin for bypassing. Please

refer to layout recommendations.

VDD

The VDD pin supplies the power to the internal power to

the control and reference circuitry. The VDD is powered

from VIN. A small 0.1µF capacitor is recommended for

bypassing.

The enable pin provides a logic level control of the

output. In the off state, supply current of the device is

greatly reduced (typically <0.1µA). Also, in the off state,

the output drive is placed in a "tri-stated" condition,

where bipolar output transistor is in an “off” or non-

conducting state. Do not drive the enable pin above the

supply voltage.

The SS pin is the soft start pin which allows the

monotonic buildup of output when the MIC2605/6 comes

up during turn on. The SS pin gives the designer the

flexibility to have a desired soft start by placing a

capacitor SS to ground. A 0.1µF capacitor is used for in

the circuit.

The feedback pin (FB) provides the control path to

control the output. For fixed output controller output is

directly connected to feedback (FB) pin.

The switch (SW) pin connects directly to the inductor

and provides the switching current necessary to operate

in PWM mode. Due to the high speed switching and high

voltage associated with this pin, the switch node should

be routed away from sensitive nodes.

PGND

Power ground (PGND) is the ground path for the high

current PWM mode. The current loop for the power

ground should be as small as possible and separate

from the Analog ground (AGND) loop. Refer to the layout

considerations for more details.

VOUT

VOUT pin is the cathode of pin of internal schottky

diode. This pin is connected to output cap. At least 1µF

cap is recommended very close to the VOUT pin and

PGND.

Micrel, Inc. MIC2605/6

August 2008 9 M9999-080108-B

Application Information

DC-to-DC PWM Boost Conversion

The MIC2605/6 is a constant frequency boost converter.

It operates by taking a DC input voltage and regulating a

higher DC output voltage. Figure 2 shows a typical

circuit. Boost regulation is achieved by turning on an

internal switch, which draws current through the inductor

(L1). When the switch turns off, the inductor’s magnetic

field collapses, causing the current to be discharged into

the output capacitor through an internal Schottky diode.

Voltage regulation is achieved through pulse-width

modulation (PWM).

10µH

499

12.4K

MIC2605/6

VIN

VIN = 12V

VOUT

32V, 30mA

PGND

1µF 1µF

OUT

0.1µF

VDD

0.1µF

Figure 2. Typical Application Circuit

Duty Cycle Considerations

Duty cycle refers to the switch on-to-off time ratio and

can be calculated as follows for a boost regulator:

OUT

D−= 1

The duty cycle required for voltage conversion should be

less than the maximum duty cycle of 85%. Also, in light

load conditions where the input voltage is close to the

output voltage, the minimum duty cycle can cause pulse

skipping. This is due to the energy stored in the inductor

causing the output to overshoot slightly over the

regulated output voltage. During the next cycle, the error

amplifier detects the output as being high and skips the

following pulse. This effect can be reduced by increasing

the minimum load or by increasing the inductor value.

Increasing the inductor value reduces peak current,

which in turn reduces energy transfer in each cycle.

Overvoltage Protection

For the MIC2605/6 there is an over voltage protection

function. If the output voltage overshoots the set voltage

by 15% when feedback is high during input higher than

output, turn on, load transients, line transients, load

disconnection etc. the MIC2605/6 OVP ckt will shut the

switch off saving itself and other sensitive circuitry

downstream.

Component Selection

Inductor

Inductor selection is a balance between efficiency,

stability, cost, size, and rated current. For most

applications, a 10µH is the recommended inductor

value; it is usually a good balance between these

considerations. Large inductance values reduce the

peak-to-peak ripple current, affecting efficiency. This has

an effect of reducing both the DC losses and the

transition losses. There is also a secondary effect of an

inductor’s DC resistance (DCR). The DCR of an inductor

will be higher for more inductance in the same package

size. This is due to the longer windings required for an

increase in inductance. Since the majority of input

current (minus the MIC2605/6 operating current) is

passed through the inductor, higher DCR inductors will

reduce efficiency. To maintain stability, increasing

inductor size will have to be met with an increase in

output capacitance. This is due to the unavoidable “right

half plane zero” effect for the continuous current boost

converter topology. The frequency at which the right half

plane zero occurs can be calculated as follows:

(

)

ILVD

FRHPZ ⋅⋅⋅

⋅

The right half plane zero has the undesirable effect of

increasing gain, while decreasing phase. This requires

that the loop gain is rolled off before this has significant

effect on the total loop response. This can be

accomplished by either reducing inductance (increasing

RHPZ frequency) or increasing the output capacitor

value (decreasing loop gain).

Output Capacitor

Output capacitor selection is also a trade-off between

performance, size, and cost. Increasing output

capacitance will lead to an improved transient response,

but also an increase in size and cost. X5R or X7R

dielectric ceramic capacitors are recommended for

designs with the MIC2605/6. Y5V values may be used,

but to offset their tolerance over temperature, more

capacitance is required.

Input capacitor

A minimum 1F ceramic capacitor is recommended for

designing with the MIC2605/6. Increasing input

capacitance will improve performance and greater noise

immunity on the source. The input capacitor should be

as close as possible to the inductor and the MIC2605/6,

with short traces for good noise performance.

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Feedback Resistors

The MIC2605/6 utilizes a feedback pin to compare the

output to an internal reference. The output voltage is

adjusted by selecting the appropriate feedback resistor

network values. The R2 resistor value must be less than

or equal to 1k (R2  1k). The desired output voltage

can be calculated as follows:

⎟

⎠

⎞

⎜

⎝

⎛+⋅= 1

VV REFOUT

where VREF is equal to 1.25V.

Micrel, Inc. MIC2605/6

August 2008 11 M9999-080108-B

1µF/25V

1 2

SS 5

VDD

VIN

FB 6

SW 7

U1 MIC2605/6-YML

PGND

IN 4.5V to 12V

GND

10k

0.1µF/50V

10µH

12.4k

1µF/50V

VOUT 32V

GND

VOUT 1

0.1µF/50V

N.U.

Bill of Materials

Item Part Number Manufacturer Description Qty.

C1608X5R1E105K TDK(1) Capacitor, 1µF, 25V, X5R, Size 0603

06033D105MAT AVX(2) Capacitor, 1µF, 25V, X5R, Size 0603

08055D105MAT AVX(2) Capacitor, 1µF, 50V, X5R, Size 0805

VJ0603Y104KXAAT Vishay(3) Capacitor, 0.1µF, 50V, X7R, 0603

06035C104MAT AVX(2) Capacitor, 0.1µF, 50V, X7R, 0603

GRM188R71C104KA01D Murata(4) Capacitor, 0.1µF, 16V, X7R, 0603

VJ0603Y104KXAAT Vishay(3) Capacitor, 0.1µF, 50V, X7R, 0603

06035C104MAT AVX(2) Capacitor, 0.1µF, 50V, X7R, 0603

GRM188R71C104KA01D Murata(4) Capacitor, 0.1µF, 16V, X7R, 0603

C4 08055D105MAT AVX(2) Capacitor, 1µF, 50V, X5R, Size 0805 1

C5 N.U. ----- ----- 1

LQH43CN100K03 Murata(4) 10µH, 0.65mA, DCR 240m

VLCF4020T-100MR85 TDK(1) 10uH, 0.85A-1.22A, DCR 120m

R1 CRCW06031242FKEA Vishay Dale(3) Resistor, 12.4k, 1%, 1/16W, Size 0603 1

R2 CRCW06034990FKEA Vishay Dale(3) Resistor, 499, 1%, 1/16W, Size 0603 1

R3 CRCW060310K0FKEA Vishay Dale(3) Resistor, 10k, 1%, 1/16W, Size 0603 1

U1 MIC2605/6-YML Micrel, Inc.(5) 0.5A, 1.2MHz/2MHz Wide Input Range Integrated

Switch Boost Regulator 1

Notes:

1. TDK: www.tdk.com

2. AVX: www.avx.com

3. Vishay: www.vishay.com

4. Murata: www.murata.com

6. Micrel, Inc.: www.micrel.com

Micrel, Inc. MIC2605/6

August 2008 12 M9999-080108-B

PCB Layout Recommendations

Top Layer

Bottom Layer

Micrel, Inc. MIC2605/6

August 2008 13 M9999-080108-B

Package Information

8-Pin 2mm x 2mm MLF® (ML)

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com

The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its

use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant

into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A

Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully

indemnify Micrel for any damages resulting from such use or sale.