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产品型号MIC4576BU的概述

MIC4576BU 芯片概述 MIC4576BU 是一种专门设计用于开关电源和功率转换器的高效 DC-DC 转换器芯片。该芯片的主要功能是将输入电压转换为所需的输出电压，广泛应用于电池供电设备、工业控制系统、通信设备等领域。MIC4576BU 支持多种工作模式，具有高效率、高输出电流和较宽的输入电压范围，能够满足现代电子设计的多种需求。详细参数 1. 工作电压范围: MIC4576BU 的输入电压范围通常为 4.5V 至 20V，使得其能够适应各种电源供给条件。 2. 输出电流: 该芯片能持续提供最高达到 3A 的输出电流，适合大功率产品的需求。 3. 开关频率: MIC4576BU 的开关频率可调，通常在 100kHz 至 500kHz 之间。这一特性允许设计师根据具体应用需求调整转换器的性能优化。 4. 效率: MIC4576BU 的转换效率可达到 90% 以上，在一定条件下还可...

产品型号MIC4576BU的Datasheet PDF文件预览

MIC4576

Micrel

MIC4576

200kHz Simple 3A Buck Voltage Regulator

General Description

Features

The MIC4576 is a series of easy to use fixed and adjustable

BiCMOS step-down (buck) switch-mode voltage regulators.

The 200kHz MIC4576 duplicates the pinout and function of

the 52kHz LM2576. The higher switching frequency may

allow up to a 2:1 reduction in output filter inductor size.

• Fixed 200kHz operation

• 3.3V, 5V, and adjustable output versions

• Voltage over specified line and load conditions:

Fixed version: ±3% max. output voltage

Adjustable version: ±2% max. feedback voltage

• Guaranteed 3A switch current

• Wide 4V to 36V input voltage range

• Wide 1.23V to 33V output voltage range

• Requires minimum external components

• < 200µA typical shutdown mode

The MIC4576 is available in 3.3V, and 5V fixed output

versions or a 1.23V to 33V adjustable output version. Both

versions are capable of driving a 3A load with excellent line

and load regulation.

The feedback voltage is guaranteed to ±2% tolerance for

adjustable versions, and the output voltage is guaranteed to

±3% for fixed versions, within specified voltages and load

conditions. The oscillator frequency is guaranteed to ±10%.

• 75% efficiency (adjustable version > 75% typical)

• Standard inductors are 25% of typical LM2576 values

• Thermal shutdown

• Overcurrent protection

In shutdown mode, the regulator draws less than 200µA

standby current. The regulator performs cycle-by-cycle

current limiting and thermal shutdown for protection under

fault conditions.

• 100% electrical thermal limit burn-in

Applications

• Simple high-efficiency step-down (buck) regulator

• Efficient preregulator for linear regulators

• On-card switching regulators

• Positive-to-negative converter (inverting buck-boost)

• Battery Charger

• Negative boost converter

This series of simple switch-mode regulators requires a

minimum number of external components and can operate

using a standard series of inductors. Frequency compensa-

tion is provided internally.

The MIC4576 is available in TO-220 (T) and TO-263 (U)

packages for the industrial temperature range.

• Step-down to 3.3V for Intel Pentium™

and similar microprocessors

Typical Applications

5V/3A

Shutdown

Enable

SHDN

MIC4576-5.0BT

V_INFB

33µH

8V to 36V

1000µF

16V

470µF

63V

GND

MBR360

Fixed Regulator

68µH

12V/3A

1000µF

16V

Shutdown

Enable

SHDN

MIC4576BT

13.0k

16V to 36V

V_IN

470µF

63V

GND

1.50k

MBR360

Adjustable Regulator

MIC4576

4-128

April 1998•

MIC4576

Micrel

Ordering Information

Part Number

Voltage

3.3V

Temperature Range

–40°C to +85°C

Package

MIC4576-3.3BT

MIC4576-5.0BT

MIC4576BT

5-lead TO-220

5-lead TO-263

5.0V

Adjustable

3.3V

MIC4576-3.3BU

MIC4576-5.0BU

MIC4576BU

5.0V

Adjustable

Pin Configuration

SHDN

GND

V_IN

5-Lead TO-220 (T)

SHDN

GND

V_IN

5-Lead TO-263 (U)

Pin Description

Pin Number

Pin Name

V_IN

Pin Function

Supply Voltage (Input): Unregulated +4V to +36V supply voltage.

Switch (Output): Emitter of NPN output switch. Connect to external storage

inductor and Shottky diode.

3, TAB

GND

Ground

Feedback (Input): Output voltage feedback to regulator. Connect to output

of supply for fixed versions. Connect to 1.23V tap of resistive divider for

adjustable versions.

SHDN

Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts

down regulator.

April 1998•

4-129

MIC4576

Micrel

Absolute Maximum Ratings

Operating Ratings

Supply Voltage (V ) ...................................................+40V

Supply Voltage (V ) ...................................................+36V

Shutdown Voltage (V

) .......................... –0.3V to +36V

Junction Temperature ............................................. +150°C

SHDN

Output Switch (V ), Steady State...............................–1V

Package Thermal Resistance

TO-220, TO-263 (θ ) .........................................65°C/W

Feedback Voltage (V ) [Adjustable] .........................+3.8V

TO-220, TO-263 (θ ) ...........................................2°C/W

Storage Temperature ............................... –65°C to +150°C

Electrical Characteristics

V_IN= 12V; I_LOAD= 500mA; T_J= 25°C, bold values indicate –40°C ≤ T_J≤ +85°C; unless noted.

Parameter

Condition

Min

Typ

Max

Units

MIC4576 [Adjustable]

Feedback Voltage

1.217 1.230 1.243

1.193 1.230 1.267

8V ≤ V_IN≤ 36V, 0.5A ≤ I_LOAD≤ 3A

1.180

1.280

Efficiency

I_LOAD= 3A, Note 1

Maximum Duty Cycle (On)

Output Leakage Current

V_FB= 1.0V

V_IN= 36V, V_FB= 1.5V

output = 0V

output = –1V

7.5

Quiescent Current

V_FB= 1.5V

Feedback Bias Current

100

500

MIC4576-3.3

Output Voltage

3.234

3.3

3.366

6V ≤ V_IN≤ 36V, 0.5A ≤ I_LOAD≤ 3A

3.168

3.135

3.432

3.465

Efficiency

I_LOAD= 3A

V_FB= 2.5V

Maximum Duty Cycle (On)

Output Leakage Current

V_IN= 36V, V_FB= 4.0V

output = 0V

output = –1V

7.5

Quiescent Current

MIC4576-5.0

V_FB= 4.0V

Output Voltage

4.900

5.0

5.100

8V ≤ V_IN≤ 36V, 0.5A ≤ I_LOAD≤ 3A

4.800

4.750

5.200

5.250

Efficiency

I_LOAD= 3A

V_FB= 4.0V

Maximum Duty Cycle (On)

Output Leakage Current

V_IN= 36V, V_FB= 6.0V

output = 0V

output = –1V

7.5

Quiescent Current

V_FB= 6.0V

MIC4576

4-130

April 1998•

MIC4576

Micrel

Parameter

Condition

Min

Typ

Max

Units

MIC4576 / -3.3 / -5.0

Oscillator Frequency

Saturation Voltage

180

200

1.7

220

kHz

_OUT= 3A

2.3

2.5

Current Limit

peak current, t_ON≤ 3µs; V_FB= 0V

4.2

3.5

5.2

6.9

7.5

Standby Quiescent Current

SHDN Input Logic Level

V_SHDN= 5V (regulator off), V_FB= 0V

V_OUT= 0V (regulator off)

200

µA

2.2

2.4

1.4

V_OUT= 3.3V or 5V (regulator on)

1.2

1.0

0.8

SHDN Input Current

_SHDN= 5V (regulator off)

0.01

µA

V_SHDN= 0V (regulator on)

–10

General Note: Devices are ESD protected, however, handling precautions are recommended.

Note 1: = 5V

OUT

April 1998•

4-131

MIC4576

Micrel

Block Diagrams

+36V max.

V_IN

C_IN

Shutdown

Enable

Internal

Regulator

SHDN

Thermal

Shutdown

Current

Limit

200kHz

Oscillator

Driver

Com-

parator

V_OUT

C_OUT

Switch

1.23V

Bandgap

Error

Amp.

GND

MIC4576-x.x

Block Diagram with External Components

Fixed Step-Down Regulator

+36V max.

V_IN

C_IN

Shutdown

Enable

Internal

Regulator

SHDN

+ 1

OUT

REF

Thermal

Shutdown

Current

Limit

200kHz

Oscillator

OUT

REF

Driver

Com-

parator

V_OUT

C_OUT

Switch

1.23V

Bandgap

Error

Amp.

[Adjustable]

MIC4576

GND

Block Diagram with External Components

Adjustable Step-Down Regulator

MIC4576

4-132

April 1998•

MIC4576

Micrel

Functional Description

The MIC4576 is a variable duty cycle switch-mode regulator

with an internal power switch. Refer to the block diagrams.

A higher feedback voltage increases the error amplifier

output voltage. A higher error amplifier voltage (comparator

inverting input) causes the comparator to detect only the

peaks of the sawtooth, reducing the duty cycle of the com-

parator output. A lower feedback voltage increases the duty

cycle.

Supply Voltage

The MIC4576 operates from a +4V to +36V unregulated

input. Highest efficiency operation is from a supply voltage

around +15V.

Output Switching

Enable/Shutdown

When the internal switch is on, an increasing current flows

The shutdown (SHDN) input is TTL compatible. Ground the

input if unused. A logic-low enables the regulator. A logic-

high shuts down the internal regulator which reduces the

current to typically 50µA.

from the supply V through external storage inductor L1, to

IN,

output capacitor C

and the load. Energy is stored in the

OUT

inductor as the current increases with time.

When the internal switch is turned off, the collapse of the

magnetic field in L1 forces current to flow through fast

Feedback

Fixed versions of the regulator have an internal resistive

divider from the feedback (FB) pin. Connect FB directly to the

output line.

recovery diode D1, charging C

OUT

Output Capacitor

External output capacitor C

provides stabilization and

OUT

Adjustable versions require an external resistive voltage

divider from the output voltage to ground, connected from the

1.23V tap to FB.

reduces ripple.

Return Paths

During the on portion of the cycle, the output capacitor and

load currents return to the supply ground. During the off

portion of the cycle, current is being supplied to the output

capacitor and load by storage inductor L1, which means that

D1 is part of the high-current return path.

Duty Cycle Control

A fixed-gain error amplifier compares the feedback signal

with a 1.23V bandgap voltage reference. The resulting error

amplifier output voltage is compared to a 200kHz sawtooth

waveform to produce a voltage controlled variable duty cycle

output.

Applications Information

The applications circuits that follow have been constructed

and tested. Refer to Application Note 15 for additional

information, including efficiency graphs and manufacturer’s

addresses and telephone numbers for most circuits.

For a mathematical approach to component selection and

circuit design, refer to Application Note 14.

3.3V/3A

SHDN

MIC4576-3.3BT

V_INFB

SHDN

MIC4576-3.3BT

V_INFB

33µH

6V to 24V

6V to 36V

1000µF

16V

1000µF

16V

470µF

35V

470µF

63V

GND

1N5822

MBR360

C1 Nichicon UPL1V471MPH, ESR = 0.046Ω

C2 Nichicon UPL1C221MPH, ESR = 0.047Ω

D1 Motorola 1N5822

C1 Nichicon UPL1J471MRH, ESR = 0.039Ω

C2 Nichicon UPL1C102MPH, ESR = 0.047Ω

D1 Motorola MBR360

L1 Coiltronics PL52C-33-1000, DCR = 0.036Ω

L1 Coiltronics PL52C-33-1000 DCR = 0.036

L1 Bi

HM77-30004, DCR = 0.045Ω, Note 2

L1 Bi

HM77-30004, DCR = 0.045Ω, Note 2

Figure 1. 6V–24V to 3.3V/3A Buck Converter

Through Hole

Figure 2. 6V–36V to 3.3V/3A Buck Converter

Through Hole

Note 2: Surface-mount component.

April 1998•

4-133

MIC4576

Micrel

5V/3A

SHDN

MIC4576-5.0BT

V_INFB

SHDN

MIC4576-5.0BT

V_INFB

33µH

8V to 24V

8V to 36V

1000µF

16V

1000µF

16V

470µF

35V

470µF

63V

GND

1N5822

MBR360

C1 Nichicon UPL1J471MRH, ESR = 0.039Ω

C2 Nichicon UPL1C102MPH, ESR = 0.047Ω

D1 Motorola MBR360

C1 Nichicon UPL1J471MPH, ESR = 0.046Ω

C2 Nichicon UPL1C102MPH, ESR = 0.047Ω

D1 Motorola MBR5822

L1 Coiltronics PLS2C-33-1000, DCR = 0.036

L1 Coiltronics PL52C-33-1000, DCR = 0.036

L1 Bi

HM77-30004, DCR = 0.045Ω, Note 2

L1 Bi

HM77-30004, DCR = 0.045Ω, Note 2

Figure 4. 8V–36V to 5V/3A Buck Converter

Through Hole

Figure 3. 8V–24V to 5V/3A Buck Converter

Through Hole

12V/3A

SHDN

68µH

MIC4576BT

13.0k

16V to 36V

1000µF

16V

V_IN

470µF

63V

GND

1.50k

MBR360

C1 Nichicon UPL1J471MPH, ESR = 0.039Ω

C2 Nichicon UPL1C102MPH, ESR = 0.047Ω

D1 Motorola MBR360

L1 Bi

HM77-29006, DCR = 0.08Ω

Figure 5. 16V–36V to 12V/3A Buck Converter

Through Hole

0.1Ω

V_OUT

5V/4A

SHDN

MIC4576-5.0BT

V_INFB

33µH

V_IN

8V to 36V

1000µF

16V

10K

GND

MBR360

470µF

63V

0.01µF

V_IN

LM358

SHDN

MIC4576-5.0BT

V_INSW

0.1Ω

33µH

GND

470µF

63V

1000µF

16V

MBR360

C1, C3 Nichicon UPL1J471MRH, ESR = 0.039Ω

C2, C4 Nichicon UPL1C102MPH, ESR = 0.047Ω

D1, D2 Motorola MBR360

L1, L2 Coiltronics PL52C-33-1000, DCR = 0.036

R1, R2 KRL

SP-1-A1-0R100J

LM358

National

Figure 6. Parallel Switching Regulators

Note 2: Surface-mount component.

MIC4576

4-134

April 1998•

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产品型号MIC4576BU的概述

产品型号MIC4576BU的Datasheet PDF文件预览

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