December 10, 2001

1

MIC2184

MIC2184

Micrel

MIC2184

Low Voltage Buck PWM Control IC

Final Information

General Description

Micrel’s MIC2184 is a high efficiency PWM buck control IC.

With its wide input voltage range of 2.9V to 14V, the MIC2184

can be used to efficiently step voltages down in 1- or 2-cell Li

Ion battery powered applications, as well as in fixed 3.3V, 5V,

or 12V systems.

Efficiencies over 90% are achievable over a wide range of

load conditions with the MIC2184’s PWM control scheme.

The operating frequency can be divided by two by raising the

FREQ/2 pin to V

versus board space. It also allows the MIC2184 to be exter-

nally synchronized to frequencies below its nominal 400KHz.

The MIC2184 features an oscillator output, FreqOut, which

can be used to implement a simple charge pump in low

voltage applications. The output of the charge pump can be

fed into the gate drive power circuitry via the V

allowing enhanced gate drive, hence higher efficiencies,

despite low input voltages.

MIC2184 features a 1

µA shutdown mode, and a program-

mable undervoltage lockout, making it well suited for portable

applications.

The MIC2184 is available in 16 pin SOP and QSOP package

options with a junction temperture range range from –40

°C

to +125

°C.

Typical Application

FreqOut

VINA

EN/UVLO

2.5V @5A

FREQ/2

VDD

COMP

SS

VREF

SYNC

SGND

MIC2184

VINP

CSH

CSL

OUTP

PGND

FB

1

7

2

16

10

4

3

13

11

5

16

9

8

14

12

6

120

µF (x2)

6.3V

15m

Ω

Q3

Si9803DY(x2)

4.7

µH

220

µF(x2)

6.3V

Adjustable Output Buck Converter

Features

• Input voltage range: 2.9V to 14V

• >90% efficiency

• Oscillator frequency of 400kHz

• Frequency divide-by-two pin

• Frequency sync to 600kHz

• FrequOut oscillator output allows simple charge pump

implementation in low voltage systems

• 1.245V reference output

• Front edge blanking

•5

Ω output driver

• Soft start

• PWM current mode control

•1

µA shutdown current

• Cycle-by-cycle current limiting

• Frequency foldback short circuit protection

• Adjustable under-voltage lockout

• 16 pin narrow-body SOIC and QSOP package options

Applications

• 3.3V to 2.5V/1.8V/1.5V conversion

• DC power distribution systems

• Wireless Modems

• ADSL line cards

• 1-and 2-cell Li Ion battery operated equipment

• Satellite Phones

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

50

55

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95

100

012

345

OUTPUT CURRENT (A)

MIC2184 EFFICIENCY

V

IN

= 3.3V

V

OUT

= 2.5V

f

S

= 200kHz