Micrel MIC4720 User Manual

General Description

MIC4720

3mm x 3mm 2.0MHz 2A Integrated

Features

Switch Buck Regulator

The Micrel MIC4720 is a high efficiency PWM buck (step­down) regulator that provides up to 2A of output current.
The MIC4720 operates at 2.0MHz and has proprietary
internal compensation that allows a closed loop bandwidth
of over 200KHz.

The low on-resistance internal p-channel MOSFET of the
MIC4720 allows efficiencies over 92%, reduces external
components count and eliminates the need for an
expensive current sense resistor.

The MIC4720 operates from 2.7V to 5.5V input and the
output can be adjusted down to 1V. The devices can
operate with a maximum duty cycle of 100% for use in low­dropout conditions.

The MIC4720 is available in the exposed pad 12-pin
3mm x 3mm MLF

®

and 10-pin ePad MSOP package with a

junction operating range from –40°C to +125°C.

Typical Application

• 2.7 to 5.5V supply voltage

• 2.0MHz PWM mode

• Output current to 2A

• Up to 94% efficiency

• 100% maximum duty cycle

• Adjustable output voltage option down to 1V

• Ultra-fast transient response

• Ultra-small external components

Stable with a 1µH inductor and a 4.7µF output
capacitor

• Fully integrated 2A MOSFET switch

• Micropower shutdown

• Thermal shutdown and current limit protection

• Pb-free 12-pin 3mm x 3mm MLF

®

package

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

• Pb-free 10-pin ePad MSOP package

Applications

• FPGA/DSP/ASIC applications

• General point of load

• Broadband communications

• DVD/TV recorder

• Point of Sale

• Printers/Scanners

• Set Top Boxes

• Computing Peripherals

• Video Cards

MIC4720

2A 2.0MHz Buck Regulator

MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (

May 2007

MIC4720

3.3V

Efficiency

100

EFFICIENCY (%)

95

90

85

80

75

70

65

OUT

VIN = 5.0V

0

0.2

0.4

0.6

0.811.2

OUTPUT CURRENT (A)

VIN = 4.5V

VIN = 5.5V

408

) 944-0800 • fax + 1 [phone] • http://www.micrel.com

2

1.4

1.6

1.8

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Micrel, Inc. MIC4720

Ordering Information

Part Number Voltage Junction Temp. Range Package Lead Finish

MIC4720YML Adj. –40° to +125°C 12-Pin 3x3 MLF

MIC4720YMME Adj. –40° to +125°C

Pin Configuration

SW

1

VIN

2

PGND

SGND

3

4

BIAS EN

5

67

FB NC

12-Pin 3mm x 3mm MLF® (ML)

EP

12

11

10

9

8

SW

VIN

PGND

PGOOD

®

10-Pin ePad

MSOP

1SW

VIN

2

SGND

3

BIAS

4

FB EN65

10-Pin ePad MSOP (MM)

Pb-Free

Pb-Free

10 SW

9

8

7

VIN

PGND

PGOOD

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Micrel, Inc. MIC4720

Pin Description

Pin Number

MLF

®

1,12 1, 10 SW Switch (Output): Internal power P-Channel MOSFET output switch

2,11 2, 9 VIN

3,10 8 PGND Power Ground. Provides the ground return path for the high-side drive current.

4 3 SGND

5 4 BIAS

6 5 FB

7 — NC

8 6 EN

9 7 PGOOD

EP — GND Connect to ground.

Pin Number

MSOP

Pin Name Pin Function

Supply Voltage (Input): Supply voltage for the source of the internal P-channel
MOSFET and driver.

Requires bypass capacitor to GND.

Signal (Analog) Ground. Provides return path for control circuitry and internal
reference.

Internal circuit bias supply. Must be bypassed with a 0.1µF ceramic capacitor to
SGND.

Feedback. Input to the error amplifier, connect to the external resistor divider
network to set the output voltage.

No Connect. Not internally connected to die. This pin can be tied to any other pin
if desired.

Enable (Input). Logic level low, will shutdown the device, reducing the current
draw to less than 5µA.

Power Good. Open drain output that is pulled to ground when the output voltage
is within +/- 7.5% of the set regulation voltage

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Absolute Maximum Ratings

(1)

Operating Ratings

(2)

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

Output Switch Voltage (V
Output Switch Current (
Logic Input Voltage (V

). .........................................+6V

SW

).............................................11A

SW

) ..................................–0.3V to V

EN

Storage Temperature (Ts) .........................–60°C to +150°C

Supply voltage (VIN) ..................................... +2.7V to +5.5V

Logic Input Voltage (V

) ....................................... 0V to V

EN

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

Junction Thermal Resistance

IN

3mm×3mm MLF-12 (θ
3mm×3mm MLF-12 (θ
10 pin ePad MSOP (θ
10 pin ePad MSOP (θ

) ................................... 60°C/W

JA

)...................................10°C/W

JC

).................................... 76°C/W

JA

)....................................28°C/W

JC

IN

Electrical Characteristics

VIN = VEN = 3.6V; L = 1µH; C

Parameter Condition Min Typ Max Units

Supply Voltage Range

Under-Voltage Lockout Threshold (turn-on)

UVLO Hysteresis 100 mV

Quiescent Current VFB = 0.9 × V

Shutdown Current VEN = 0V 2

[Adjustable] Feedback Voltage

FB pin input current 1 nA

Current Limit VFB = 0.9 × V

Output Voltage Line Regulation

Output Voltage Load Regulation 20mA < I

Maximum Duty Cycle

Switch ON-Resistance

Oscillator Frequency

Enable Threshold

Enable Hysteresis

Enable Input Current 0.1

Power Good Range ±7 ±10 %

Power Good Resistance I

Over-Temperature Shutdown 160

Over-Temperature Hysteresis 25

Notes:

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

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

3. Specification for packaged product only.

(3)

= 4.7µF; TA = 25°C, unless noted. Bold values indicate –40°C< TJ < +125°C.

OUT

(not switching) 570

NOM

± 2% (over temperature) I

3.5 5

NOM

V

> 2V; VIN = V

OUT

V

< 2V; VIN = 2.7V to 5.5V; I

OUT

< 2A 0.2

LOAD

V

≤ 0.4V

FB

I

= 200mA VFB = GND (High Side Switch)

SW

+500mV to 5.5V; I

OUT

LOAD

= 100mA

= 100mA

LOAD

LOAD

= 100mA

2.7

2.45

0.98

0.07 %

100

95 200

2.55

%

= 500µA 150

PGOOD

1.8

0.5

2.0

0.85

50

5.5

2.65

900

10

1.02

300

2.2

1.3

2.3

250

V

V

µA

µA

V

A

%

mΩ

MHz

V

mV

µA

Ω

°C
°C

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Micrel, Inc. MIC4720

Typical Characteristics

1.8V

93
91
89
87
85

VIN = 3.3V

83
81
79
77
75
73

EFFICIENCY (%)

71
69
67
65

0

0.2

0.4

OUTPUT CURRENT (A)

2.5V

95

90

VIN = 3.3V

85

80

EFFICIENCY (%)

75

70

0

0.2

0.4

OUTPUT CURRENT (A)

3.3V

100

95

90

VIN = 5.0V

85

80

75

EFFICIENCY (%)

70

65

0

0.2

0.4

OUTPUT CURRENT (A)

1.2V

85

83

81

79

VIN =3.3V

77

75

73

71

EFFICIENCY (%)

69

67

65

0

0.2

0.4

OUTPUT CURRENT (A)

MIC4720

Efficiency

OUT

VIN = 3.6V

0.6

0.811.2

MIC4720

Efficiency

OUT

0.6

0.811.2

MIC4720

Efficiency

OUT

0.6

0.811.2

MIC4720

Efficiency

OUT

0.6

0.811.2

VIN = 3.0V

1.4

VIN = 3.6V

1.4

VIN = 4.5V

VIN = 5.5V

1.4

VIN =3.0V

VIN =3.6V

1.4

1.6

1.6

1.6

1.6

1.8

1.8

1.8

1.8

MIC4720

Efficiency

1.8V

90

85

80

75

EFFICIENCY (%)

70

2

65

0

OUT

VIN = 4.5V

VIN = 5.0V

0.2

0.4

OUTPUT CURRENT (A)

0.6

0.811.2

VIN = 5.5V

1.4

1.6

1.8

95

90

85

80

75

EFFICIENCY (%)

70

2

65

0

MIC4720

1.5V

Efficiency

90

85

80

75

EFFICIENCY (%)

70

2

65

0

OUT

VIN = 3.0V

VIN = 3.3V

VIN = 3.6V

0.2

0.4

0.6

0.811.2

OUTPUT CURRENT (A)

1.4

1.6

1.8

85

83

81

79

77

75

73

71

EFFICIENCY (%)

69

67

2

65

0

MIC4720

1V

Efficiency

80

75

70

65

60

55

50

45

EFFICIENCY (%)

40

35

2

30

80

78

76

74

72

70

68

66

EFFICIENCY (%)

64

62

2

60

OUT

VIN = 5.0V

0

0.2

0.4

0.6

0.811.2

OUTPUT CURRENT (A)

MIC4720

Efficiency

1.2V

OUT

VIN = 5.0V

0

0.2

0.4

0.6

0.811.2

OUTPUT CURRENT (A)

VIN = 4.5V

VIN = 5.5V

1.4

1.6

VIN = 4.5V

VIN = 5.5V

1.4

1.6

1.8

1.8

2

2

85

80

75

70

65

60

EFFICIENCY (%)

55

50

0

1.0010

1.0008

1.0006

1.0004

1.0002

1.0000

0.9998

0.9996

0.9994

0.9992

0.9990

2.7 3.2 3.7 4.2 4.7 5.2

MIC4720

Efficiency

2.5V

OUT

VIN = 5.0V

0.2

0.4

0.6

OUTPUT CURRENT (A)

VIN = 4.5V

VIN = 5.5V

0.811.2

1.4

MIC4720

Efficiency

1.5V

OUT

VIN = 4.5V

VIN = 5.0V

0.2

0.4

OUTPUT CURRENT (A)

0.6

0.811.2

VIN = 5.5V

1.4

MIC4720

Efficiency

1V

OUT

VIN = 3.0V

VIN = 3.3V

0.2

0.4

OUTPUT CURRENT (A)

0.6

0.811.2

VIN = 3.6V

1.4

Line Regulation

SUPPLY VOLTAGE (V)

1.6

1.6

1.6

1.8

1.8

1.8

2

2

2

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Typical Characteristics (cont.)

Feedback Voltage

1.010

1.008

1.006

1.004

1.002

1.000

0.998

0.996

0.994

0.992

0.990

vs. Temperature

VIN = 3.3V

20 40 60 80

TEMPERATURE (°C)

Quiescent Current
vs. Supply Voltage

800

700

600

500

400

300

200

100

0

0123456

SUPPLY VOLTAGE (V)

VEN= V

Enable Threshold

vs. Supply Voltage

1.2

Frequency

2.5

2.4

2.3

2.2

2.1

2.0

1.9

1.8

1.7

1.6

1.5

120

115

110

105

100

IN

vs. Temperature

VIN = 3.3V

20 40 60 80

TEMPERATURE (°C)

R

DSON

vs. Supply Voltage

95

90

85

80

75

70

2.7 3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)

Feedback Voltage

vs. Supply Voltage

1.2

1.0

0.8

0.6

0.4

0.2
VEN = V

0

012345

160

140

120

100

80

60

40

20

0

IN

SUPPLY VOLTAGE (V)

R

DSON

vs. Temperature

VIN = 3.3V

20 40 60 80

TEMPERATURE (°C)

Enable Threshold

1.2

vs. Temperature

1.0

0.8

0.6

0.4

0.2

0

2.7
SUPPLY VOLTAGE (V)

3.73.2 4.2 4.7

1.0

0.8

0.6

0.4

0.2

0

VIN = 3.3V

20 40 60 80

TEMPERATURE (°C)

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Micrel, Inc. MIC4720

g

g

Functional Characteristics

Continuous Current

(500mA/div)

Inductor Current

(2V/div)

Switch Voltage

Time (200ns/div)

VIN = 3.3V

= 1V

V

OUT

L = 1µH

= 4.7µF

C

OUT

= 1.3A

I

OUT

e

(20mV/div)

Output Volta

(1A/div)

Output Current

Output Ripple

(2V/div)

Switch Voltage

e

Load Transient

VIN = 3.3V

= 1.0V

V

OUT

Time (100µs/div)

(10mV/div)

AC Coupled

Output Volta

VIN = 3.3V

= 1.0V

V

OUT

I

= 2A

OUT

Output Current

(2A/div)

Time (200ns/div)

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