MIC33050-4YHLTR - Micrel, Inc.

MIC33050

4MHz Internal Inductor PWM Buck

Regulator with HyperLight Load™

HyperLight Load is a trademark of Micrel, Inc.

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

December 2008 1 M9999-121008-B

General Description

The Micrel MIC33050 is a high efficiency 600mA PWM

synchronous buck (step-down) regulator with internal

inductor featuring HyperLight Load™, a patent-pending

switching scheme that offers best-in-class light load

efficiency and transient performance while providing very

small external components and low output ripple at all

loads.

The MIC33050 also has a very low typical quiescent

current draw of 20µA and can achieve over 83% efficiency

even at 1mA.

In contrast to traditional light load schemes, the HyperLight

Load™ architecture does need not trade off control speed

to obtain low standby currents and in doing so, the device

only needs a small output capacitor to absorb the load

transient as the powered device goes from light load to full

load.

At higher loads, the MIC33050 provides a constant

switching frequency of greater than 4MHz while providing

peak efficiencies greater than 93%.

The MIC33050 comes in fixed output voltage options from

0.72V to 3.3V thereby eliminating external feedback

components.

The MIC33050 is available in an 12-pin 3mm x 3mm MLF®

with a junction operating 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

• Input voltage: 2.7V to 5.5V HyperLight Load™

• 600mA output current

• Fixed output voltage options from 0.72V to 3.3V

• No external inductor required

• Ultra fast transient response

• 20µA typical quiescent current

• 4MHz in PWM in constant current mode

• Low voltage output ripple

– 25mVpp in HyperLight Load™ mode

– 3mV output voltage ripple in full PWM mode

• >93% efficiency

• >83% at 1mA

• Micropower shutdown

• 3mm x 3mm MLF®-12L

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

Applications

• Cellular phones

• Digital cameras

• Portable media players

• Wireless LAN cards

• WiFi/WiMax/WiBro modules

• USB Powered Devices

____________________________________________________________________________________________________________

Typical Application

100

1 10 100 1000

EFFICIENCY (%)

OUTPUT CURRENT (mA)

Efficiency VOUT = 1.8V

VIN = 4.2V

VIN = 3.6V

VIN = 3.0V

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December 2008 2 M9999-121008-B

Ordering Information

Part Number Voltage Temperature Range Package Lead Finish

MIC33050-4YHL 1.2V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free

MIC33050-GYHL 1.8V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free

MIC33050-SYHL 3.3V –40° to +125°C 12-Pin 3mm x 3mm MLF® Pb-Free

Note:

1. Other output voltage options available. Contact Micrel for details.

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

Pin Configur ation

12-Pin 3mm x 3mm MLF® (HL)

(Top View)

Pin Description

Pin Number Pin Name Pin Function

1 VIN Supply Voltage (Input): Requires bypass capacitor-to-GND.

9 EN

Enable (Input): Logic low will shut down the device, reducing the quiescent

current to less than 4µA. Do not leave floating.

10 SNS

Input to the error amplifier. Connect to the external resistor divider network to

set the output voltage. For fixed output voltages connect to VOUT (internal

resistor network sets the output voltage).

11 CFF Feed forward capacitor connected to out sense pin

2 PGND Power Ground

12 AGND Analog ground

3,4,5,6 SW Switch (Output): Internal power MOSFET output switches.

7,8 OUT Output after the internal inductor

E-PAD HS PAD Connect to power ground.

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Absolute Maximum Ratings(1)

Supply Voltage (VIN).........................................................6V

Output Switch Voltage (VSW) ............................................6V

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

Logic Input Voltage (VEN) .................................. –0.3V to VIN

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

ESD Rating(3).................................................................. 3kV

Operating Ratings(2)

Supply Voltage (VIN)......................................... 2.7V to 5.5V

Logic Input Voltage (VEN)…………………………-0.3V to VIN

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

Thermal Resistance

3mm x 3mm MLF®-12 (θJA)................................60°C/W

Electrical Characteristics(4)

TA = 25°C with VIN = VEN = 3.6V; CFF = 560pF; COUT = 4.7µF; IOUT = 20mA unless otherwise specified.

Bold values indicate –40°C< TJ < +125°C.

Parameter Condition Min Typ Max Units

Supply Voltage Range 2.7 5.5 V

Under-Voltage Lockout Threshold (turn-on) 2.45 2.55 2.65 V

UVLO Hysteresis 100 mV

Quiescent Current,

Hyper LL mode IOUT = 0mA , VSNS > 1.2*VOUT nominal 20 32 µA

Shutdown Current VIN = 5.5V; VEN = 0V; 0.01 4 µA

Output Voltage Accuracy VIN = 3.0V, ILOAD = 20mA –2.5 +2.5 %

Current Limit in PWM Mode SNS = 0.9*VNOM 0.65 1 1.7 A

Output Voltage Line Regulation VIN = 3.0V to 5.5V, ILOAD = 20mA 0.5 %/V

Output Voltage Load Regulation 20mA < ILOAD < 500mA, 0.3 %

Maximum Duty Cycle SNS ≤ VNOM 80 89 %

PWM Switch ON-Resistance ISW = 100mA PMOS

ISW = -100mA NMOS 0.45

0.5 Ω

Ω

Frequency ILOAD = 120mA 3.4 4 4.6 MHz

Soft Start Time VOUT = 90% 650 µs

Enable Threshold (turn-on) 0.5 0.8 1.2 V

Enable Hysteresis 35 mV

Enable Input Current 0.1 2 µA

Over-temperature Shutdown 165 °C

Over-temperature Shutdown

Hysteresis 20

°C

Notes:

1. Exceeding the absolute maximum rating may damage the device.

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

3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.

4. Specification for packaged product only.

Micrel, Inc. MIC33050

December 2008 4 M9999-121008-B

Typical Characteristics

100

1 10 100 1000

EFFICIENCY (%)

OUTPUT CURRENT (mA)

Efficiency VOUT = 3.3V

VIN = 5.0V

VIN = 4.2V

VIN = 5.5V

100

1 10 100 1000

EFFICIENCY (%)

OUTPUT CURRENT (mA)

Efficiency VOUT = 1.8V

VIN = 4.2V

VIN = 3.6V

VIN = 3.0V

100

1 10 100 1000

EFFICIENCY (%)

OUTPUT CURRENT (mA)

Efficiency VOUT = 1.2V

VIN = 2.7V

VIN = 3.6V VIN = 4.2V

Quiescent Curre nt

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

VIN = 3.6V

VOUT = 1.8V

2.7

INPUT VOLTAGE (V)

Quiescent Curre nt

vs. Input Voltage

3.23.7 4.24.7 5.2

VOUT = 1.8V

No Load

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Switchi ng Frequency

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

VIN = 3.6V

VOUT = 1.8V

Load = 150mA

2.5

3.0

3.5

4.0

4.5

5.0

5.5

2.7

INPUT VOLTAGE (V)

Switching Frequency

vs. Input Voltage

3.23.7 4.24.7 5.2

VOUT = 1.8V

Load = 150mA

0.60

0.62

0.64

0.66

0.68

0.70

0.72

0.74

0.76

0.78

0.80

Feedback Voltage

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

VIN = 3.6V

VOUT = 1.8V

No Load

1.70

1.75

1.80

1.85

1.90

Output Voltage

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

VIN = 3.6V

VOUT = 1.8V

No Load

1.70

1.75

1.80

1.85

1.90

2.7

INPUT VOLTAGE (V)INPUT VOLTAGE (V)

Output Voltage

vs. Input Voltage

3.23.7 4.24.7 5.2

Load = 20mA

1.70

1.75

1.80

1.85

1.90

0 100 200 300 400 500 600

OUTPUT CURRENT (mA)

Output Voltage

vs. Output Current

VIN = 3.6V

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Functional Characteristics

Micrel, Inc. MIC33050

December 2008 6 M9999-121008-B

Functional Characteristics (continued)

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Functional Diagram

MIC33050 Simplified Block Diagram

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Functional Description

VIN

VIN provides power to the MOSFETs for the switch mode

regulator section and to the analog supply circuitry. Due to

the high switching speeds, it is recommended that a 2.2µF

or greater capacitor be placed close to VIN and the power

ground (PGND) pin for bypassing. Refer to the layout

recommendations for details.

The enable pin (EN) controls the on and off state of the

device. A high logic on the enable pin activates the

regulator, while a low logic deactivates it. MIC33050

features built-in soft-start circuitry that reduces in-rush

current and prevents the output voltage from overshooting

at start up. Do not leave floating.

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 on this pin,

the switch node should be routed away from sensitive

nodes such as the CFF pin.

OUT

The output pin (OUT) is the output voltage pin following

the internal inductor of the device. Connect an output filter

capacitor equal to 2.2µF or greater to this pin.

SNS

The SNS pin is needed to sense the output voltage at the

output filter capacitor. In order for the control loop to

monitor the output voltage accurately it is good practice to

sense the output voltage at the positive side of the output

filter capacitor where voltage ripple is smallest.

CFF

The CFF pin is connected to the SNS pin of MIC33050

with a feed-forward capacitor of 560pF. The CFF pin itself

is compared with the internal reference voltage (VREF) of

the device and provides the control path to control the

output. VREF is equal to 0.72V. The CFF pin is sensitive to

noise and should be place away from the SW pin. Refer to

the layout recommendations for details.

PGND

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

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 recommendations for more

details.

AGND

Signal ground (AGND) is the ground path for the biasing

and control circuitry. The current loop for the signal ground

should be separate from the Power ground (PGND) loop.

Refer to the layout recommendations for more details.

Micrel, Inc. MIC33050

December 2008 9 M9999-121008-B

Applications Information

Input Capacitor

A minimum of 2.2µF ceramic capacitor should be placed

close to the VIN pin and PGND pin for bypassing. X5R or

X7R dielectrics are recommended for the input capacitor.

Y5V dielectrics, aside from losing most of their

capacitance over temperature, they also become resistive

at high frequencies. This reduces their ability to filter out

high frequency noise.

Output Capacitor

The MIC33050 was designed for use with a 2.2µF or

greater ceramic output capacitor. A low equivalent series

resistance (ESR) ceramic output capacitor either X7R or

X5R is recommended. Y5V and Z5U dielectric capacitors,

aside from the undesirable effect of their wide variation in

capacitance over temperature, become resistive at high

frequencies.

Compensation

The MIC33050 is designed to be stable with an internal

inductor with a minimum of 2.2µF ceramic (X5R) output

capacitor.

Efficiency Considerations

Efficiency is defined as the amount of useful output power,

divided by the amount of power supplied.

100

% Efficiency

ININ

OUTOUT ×

⎟

⎠

⎞

⎜

⎝

⎛

Maintaining high efficiency serves two purposes. It

reduces power dissipation in the power supply, reducing

the need for heat sinks and thermal design considerations

and it reduces consumption of current for battery powered

applications. Reduced current draw from a battery

increases the devices operating time and is critical in hand

held devices.

There are two types of losses in switching converters; DC

losses and switching losses. DC losses are simply the

power dissipation of I2R. Power is dissipated in the high

side switch during the on cycle. Power loss is equal to the

high side MOSFET RDSON multiplied by the Switch

Current2. During the off cycle, the low side N-channel

MOSFET conducts, also dissipating power. Device

operating current also reduces efficiency. The product of

the quiescent (operating) current and the supply voltage is

another DC loss. The current required driving the gates on

and off at a constant 4MHz frequency and the switching

transitions make up the switching losses.

100

1 10 100 1000

EFFICIENCY (%)

OUTPUT CURRENT (mA)

Efficiency VOUT = 1.8V

VIN = 4.2V

VIN = 3.6V

VIN = 3.0V

The Figure above shows an efficiency curve. From 1µA to

100mA, efficiency losses are dominated by quiescent

current losses, gate drive and transition losses. By using

the HyperLight Load™ mode, the MIC33050 is able to

maintain high efficiency at low output currents.

Over 100mA, efficiency loss is dominated by MOSFET

RDSON and inductor losses. Higher input supply voltages

will increase the Gate-to-Source threshold on the internal

MOSFETs, thereby reducing the internal RDSON. This

improves efficiency by reducing DC losses in the device.

All but the inductor losses are inherent to the device. In

which case, inductor selection becomes increasingly

critical in efficiency calculations. As the inductors are

reduced in size, the DC resistance (DCR) can become

quite significant. The DCR losses can be calculated as

follows;

PD = IOUT

2 × DCR

From that, the loss in efficiency due to inductor resistance

can be calculated as follows;

100

LIV

1Loss Efficiency

PDOUTOUT

OUTOUT ×

⎥

⎦

⎤

⎢

⎣

⎡

⎟

⎠

⎞

⎜

⎝

⎛

+×

−=

Efficiency loss due to DCR is minimal at light loads and

gains significance as the load is increased. Inductor

selection becomes a trade-off between efficiency and size

in this case.

Micrel, Inc. MIC33050

December 2008 10 M9999-121008-B

HyperLight Load™ Mode

The MIC33050 uses a minimum on and off time

proprietary control loop. When the output voltage falls

below the regulation threshold, the error comparator

begins a switching cycle that turns the PMOS on and

keeps it on for the duration of the minimum-on-time. When

the output voltage is over the regulation threshold, the

error comparator turns the PMOS off for a minimum-off-

time. The NMOS acts as an ideal rectifier that conducts

when the PMOS is off. Using a NMOS switch instead of a

diode allows for lower voltage drop across the switching

device when it is on. The asynchronous switching

combination between the PMOS and the NMOS allows the

control loop to work in discontinuous mode for light load

operations. In discontinuous mode, MIC33050 works in

pulse frequency modulation (PFM) to regulate the output.

As the output current increases, the switching frequency

increases. This improves the efficiency of the MIC33050

during light load currents. As the load current increases,

the MIC33050 goes into continuous conduction mode

(CCM) at a constant frequency of 4MHz. The equation to

calculate the load when the MIC33050 goes into

continuous conduction mode may be approximated by the

following formula:

⎟

⎠

⎞

⎜

⎝

⎛

×−

=f2L

D)V(V

IOUTIN

LOAD

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December 2008 11 M9999-121008-B

MIC33050 Typical Application Circuit

Bill of Materials

Item Part Number Manufacturer Description Qty

C1, C2 C1608X5R0J475K TDK(1) 4.7µF Ceramic Capacitor, 6.3V, X5R, Size 0603 2

C3 C1608C0G1H561J TDK(1) 560pF Ceramic Capacitor, 50V, NPO, Size 0603 1

U1 MIC33050-xYHL Micrel, Inc. (2) 4MHz Internal Inductor PWM Buck Regulator with

HyperLight Load™ Mode 1

Notes:

1. TDK: www.tdk.com

2. Micrel, Inc: www.micrel.com

Micrel, Inc. MIC33050

December 2008 12 M9999-121008-B

PCB Layout Recommendations

Top Layer

Bottom Layer

Micrel, Inc. MIC33050

December 2008 13 M9999-121008-B

Package Information

12-Pin 3mm x 3mm 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.