MIC3838BMM Micrel Inc, MIC3838BMM Datasheet

MIC3838BMM

Manufacturer Part Number

MIC3838BMM

Description

IC CTRLR DC/DC PUSH-PULL 10-MSOP

Manufacturer

Micrel Inc

Datasheet

1.MIC3839YMM.pdf (11 pages)

Specifications of MIC3838BMM

Pwm Type

Voltage/Current Mode

Number Of Outputs

Frequency - Max

1MHz

Duty Cycle

50%

Voltage - Supply

2 V ~ 14 V

Buck

Yes

Boost

Flyback

Inverting

Doubler

Divider

Cuk

Isolated

Yes

Operating Temperature

-40°C ~ 85°C

Package / Case

10-MSOP, Micro10™, 10-uMAX, 10-uSOP

Frequency-max

1MHz

Lead Free Status / RoHS Status

Contains lead / RoHS non-compliant

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General Description

The MIC3838 and MIC3839 are a family of complementary

output push-pull PWM control ICs that feature high speed and

low power consumption. The MIC3838/9 are ideal for telecom

level (36V to 75V) isolated step down dc/dc conversion

applications where high output current, small size, and high

efficiency are required

The MIC3838/9 are designed for high flexibility with minimum

pin-count. The devices are easily configurable for either

voltage-mode or current-mode control. Additionally, the

MIC3838/9 can easily implement a volt-second clamp that

automatically limits the duty cycle during input transients,

allowing designers to use the smallest possible transformers

and power components. A 3V reference output is also avail-

able that eliminates the need for an external reference.

The dual-ended push-pull architecture of the MIC3838/9

allows more efficient utilization of the transformer than single-

ended topologies, allowing smaller size dc/dc solutions.

Additionally, the out-of-phase push-pull topology allows a

higher effective duty cycle, reducing input and output ripple

as well as stress on the external components. The dead-time

between the two outputs is adjustable between 60ns to

200ns, limiting the duty cycle of each output stage to less than

50%.

The MIC3838 has a turn-on threshold of 12.5V whereas the

MIC3839 has a lower turn-on threshold of 4.3V. Both devices

are available in a small size MSOP-10 package with an

operating range of –40°C to +85°C.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Typical Application

April 2005

MIC3838/3839

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

36V to 75V

VREF

GND

COMP

MIC3838x-x

Voltage-Mode Half-Bridge Converter CIrcuit

Start-Up

Circuitry

RAMP

OUTA

OUTB

VDD

ILIM

Volt Sec Clamp

Feed Forward

Ramp/

Features

• Dual output drive stages in push-pull configuration

• Configurable for current-mode or voltage-mode control

• Easily implements volt-second clamp

• Leading edge current-sense blanking

• 3V reference output available

• 130µA typical start-up current

• 1mA typical run current

• Operation to 1MHz

• On-chip error amplifier with 4MHz gain bandwidth

• Internal soft start

• On-chip V

• Output drive stages capable of 500mA peak source

Applications

• High efficiency “brick” power supply modules

• Telecom equipment and power supplies

• Industrial power supplies

• 42V automotive power supplies

• Base stations

• Networking power supplies

product

current, 1A peak sink current

• Half bridge converters

• Full bridge converters

• Push-pull converters

• Voltage-fed push-pull converters

& Isolation

Reference

Flexible Push-Pull PWM Controller

clamping

MIC3838/3839

12V 100W

OUT

MIC3838/3839

Micrel

Related parts for MIC3838BMM

MIC3838BMM Summary of contents

Page 1

MIC3838/3839 General Description The MIC3838 and MIC3839 are a family of complementary output push-pull PWM control ICs that feature high speed and low power consumption. The MIC3838/9 are ideal for telecom level (36V to 75V) isolated step down dc/dc conversion ...

Page 2

... MIC3838/3839 Ordering Information Part Number Standard Lead-Free MIC3838BMM MIC3838YMM MIC3839BMM MIC3839YMM Pin Configuration Pin Description Pin Number Pin Name 1 COMP ILIM 4 RAMP GND MIC3838/3839 Turn On Turn Off Threshold Threshold Temperature Range 12.5V 8.3V 4.3V 4.1V COMP 1 10 VREF VDD ILIM 3 8 OUTA ...

Page 3

MIC3838/3839 Pin Description Pin Number Pin Name 7, 8 OUTB, OUTA 9 VDD 10 VREF April 2005 Pin Function Alternating high current output stages. Both stages are capable of driving the gate of a power MOSFET. Each stage is capable ...

Page 4

MIC3838/3839 Absolute Maximum Rating Supply Voltage (I ≤10mA) ...................................... +15V DD Supply Current ........................................................... 20mA OUTA/OUTB Source Current (peak) ...................... –0.5A OUTA/OUTB Sink Current (peak) ............................ 1.0A COMP Pin .................................................................... V Analog Inputs (FB, ILIM, RAMP) ......... –0. ...

Page 5

MIC3838/3839 Parameter Condition Undervoltage Lockout Section Start Threshold MIC3838, Note 11 MIC3839 Minimum Operating Voltage MIC3838 After Start MIC3839 Hysteresis MIC3838 MIC3839 Soft Start Section COMP Rise Time FB = 1.8V, Rise from 0. Overall Section Startup Current ...

Page 6

MIC3838/3839 Typical Characteristics MIC3838 I Current DD 10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1 (V) DD MIC3839 I Current DD vs. Temperature 1.400 10V ...

Page 7

MIC3838/3839 MIC3839 Error Amplifier Reference vs. Temperature 2.040 2.030 10V 2.020 2.010 2.000 TEMPERATURE (°C) MIC3838 Peak Current Limit vs. Temperature 0.545 0.540 0.535 0.530 V = 10V IN 0.525 0.520 0.515 -40 ...

Page 8

MIC3838/3839 Functional Diagram V = 36V to 75V IN 150k 13k V V Figure 2. Volt Second Clamp and Voltage Feed Forward Circuit Functional Description The MIC3838 high-speed power supply controller with push-pull output drive capability. MIC3838 has ...

Page 9

MIC3838/3839 Soft Start The soft start feature helps reduce surge currents at the power supply input source. An internal current source and capacitor ramp up from 0V to near V 1V/ms. The soft start feature limits the output voltage of ...

Page 10

MIC3838/3839 Max ON time dead time C Pin Oscillator eset dead time Front edge blanking AMP Pin Minimum ON time OUTA OUTB Figure 4. Timing Diagram Error Amplifier The error amplifier is part of the voltage control loop of the ...

Page 11

MIC3838/3839 Package Information 3.15 (0.122) 2.85 (0.114) 0.30 (0.012) 0.15 (0.006) 0.50 BSC (0.020) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 TEL The information furnished by Micrel in this datasheet is believed to ...

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