MIC4720
3mm x 3mm 2.0MHz 2A Integrated
Switch Buck Regulator
General Description
The Micrel MIC4720 is a high efficiency PWM buck (step-
down) 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 low-
dropout 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.
Features
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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
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
Applications
Typical Application
100
95
EFFICIENCY (%)
MIC4720
3.3V
OUT
Efficiency
V
IN
= 4.5V
V = 5.0V
IN
MIC4720
90
85
80
75
70
0
V = 5.5V
IN
1
0.2
0.4
0.6
0.8
1.2
1.4
1.6
OUTPUT CURRENT (A)
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 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
May 2007
M9999-051707
1.8
2
65
Micrel, Inc.
MIC4720
Ordering Information
Part Number
MIC4720YML
MIC4720YMME
Voltage
Adj.
Adj.
Junction Temp. Range
–40° to +125°C
–40° to +125°C
Package
12-Pin 3x3 MLF
®
10-Pin ePad
MSOP
Lead Finish
Pb-Free
Pb-Free
Pin Configuration
SW 1
VIN 2
PGND 3
SGND 4
BIAS 5
FB 6
EP
12 SW
11 VIN
10 PGND
9 PGOOD
8 EN
7 NC
10-Pin ePad MSOP (MM)
SW
VIN
SGND
BIAS
FB
1
2
3
4
5
10 SW
9 VIN
8 PGND
7 PGOOD
6 EN
12-Pin 3mm x 3mm MLF
®
(ML)
May 2007
2
M9999-051707
Micrel, Inc.
MIC4720
Pin Description
Pin Number
®
MLF
1,12
2,11
Pin Number
MSOP
1, 10
2, 9
Pin Name
SW
VIN
Pin Function
Switch (Output): Internal power P-Channel MOSFET output switch
Supply Voltage (Input): Supply voltage for the source of the internal P-channel
MOSFET and driver.
Requires bypass capacitor to GND.
3,10
4
5
6
7
8
9
EP
8
3
4
5
—
6
7
—
PGND
SGND
BIAS
FB
NC
EN
PGOOD
GND
Power Ground. Provides the ground return path for the high-side drive current.
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
Connect to ground.
May 2007
3
M9999-051707
Micrel, Inc.
MIC4720
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) .......................................................+6V
Output Switch Voltage (V
SW
). .........................................+6V
Output Switch Current (
SW
).............................................11A
Logic Input Voltage (V
EN
) .................................. –0.3V to V
IN
Storage Temperature (T
s
) .........................–60°C to +150°C
Operating Ratings
(2)
Supply voltage (V
IN
) ..................................... +2.7V to +5.5V
Logic Input Voltage (V
EN
) ....................................... 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
3mm×3mm MLF-12 (θ
JA
) ...................................60°C/W
3mm×3mm MLF-12 (θ
JC
)...................................10°C/W
10 pin ePad MSOP (θ
JA
)....................................76°C/W
10 pin ePad MSOP (θ
JC
)....................................28°C/W
Electrical Characteristics
(3)
V
IN
= V
EN
= 3.6V; L = 1µH; C
OUT
= 4.7µF; T
A
= 25°C, unless noted.
Bold
values indicate –40°C< T
J
< +125°C.
Parameter
Supply Voltage Range
Under-Voltage Lockout Threshold
UVLO Hysteresis
Quiescent Current
Shutdown Current
[Adjustable] Feedback Voltage
FB pin input current
Current Limit
Output Voltage Line Regulation
Output Voltage Load Regulation
Maximum Duty Cycle
Switch ON-Resistance
Oscillator Frequency
Enable Threshold
Enable Hysteresis
Enable Input Current
Power Good Range
Power Good Resistance
Over-Temperature Shutdown
Over-Temperature Hysteresis
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.
Condition
(turn-on)
V
FB
= 0.9 × V
NOM
(not switching)
V
EN
= 0V
±
2% (over temperature) I
LOAD
= 100mA
V
FB
= 0.9 × V
NOM
V
OUT
> 2V; V
IN
= V
OUT
+500mV to 5.5V; I
LOAD
= 100mA
V
OUT
< 2V; V
IN
= 2.7V to 5.5V; I
LOAD
= 100mA
20mA < I
LOAD
< 2A
V
FB
≤
0.4V
I
SW
= 200mA V
FB
= GND (High Side Switch)
Min
2.7
2.45
Typ
2.55
100
570
2
Max
5.5
2.65
900
10
1.02
Units
V
V
mV
µA
µA
V
nA
A
%
%
%
0.98
1
3.5
5
0.07
0.2
100
95
1.8
0.5
2.0
0.85
50
0.1
±7
200
300
2.2
1.3
2.3
±10
250
mΩ
MHz
V
mV
µA
%
Ω
°C
°C
I
PGOOD
= 500µA
150
160
25
May 2007
4
M9999-051707
Micrel, Inc.
MIC4720
Typical Characteristics
93
91
89
87
85
83
81
79
77
75
73
71
69
67
65
MIC4720
1.8V
Efficiency
OUT
1.8V
90
85
EFFICIENCY (%)
OUT
MIC4720
Efficiency
95
V = 4.5V
IN
MIC4720
2.5V
OUT
Efficiency
V = 4.5V
IN
V = 3.0V
IN
90
EFFICIENCY (%)
85
80
75
70
V = 5.0V
IN
EFFICIENCY (%)
V = 3.3V
IN
V = 3.6V
IN
80
75
70
65
V = 5.5V
IN
V = 5.0V
IN
V = 5.5V
IN
0
1
2
0
1
2
0
0.8
1
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
95
90
EFFICIENCY (%)
85
80
75
70
MIC4720
2.5V
OUT
Efficiency
V = 3.3V
EFFICIENCY (%)
IN
90
85
MIC4720
1.5V
OUT
Efficiency
V = 3.0V
IN
85
83
81
EFFICIENCY (%)
79
77
75
73
71
69
67
65
MIC4720
1.5V
OUT
Efficiency
V = 4.5V
IN
V = 3.6V
IN
80
75
70
65
V = 3.3V
IN
V = 3.6V
IN
V = 5.0V
IN
V = 5.5V
IN
0
0.8
1
1.8
2
0
0.8
1
1.8
2
0
0.8
1
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
100
95
EFFICIENCY (%)
90
85
80
75
70
0
MIC4720
3.3V
OUT
Efficiency
V = 4.5V
IN
80
75
70
EFFICIENCY (%)
65
60
55
50
45
40
35
30
MIC4720
1V
OUT
Efficiency
V = 4.5V
IN
85
80
EFFICIENCY (%)
75
70
65
60
55
MIC4720
1V
OUT
Efficiency
V = 3.0V
IN
V = 5.0V
IN
V
IN
= 5.0V
V
IN
= 5.5V
V = 5.5V
IN
V = 3.3V
IN
V = 3.6V
IN
1
2
0
0.8
1
1.8
2
0
0.8
1
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
1.2V
85
83
81
EFFICIENCY (%)
79
77
75
73
71
69
67
65
OUT
MIC4720
Efficiency
80
V =3.0V
IN
1.2V
78
76
EFFICIENCY (%)
74
72
70
68
66
64
62
60
OUT
MIC4720
Efficiency
V = 4.5V
IN
1.0010
1.0008
1.0006
1.0004
1.0002
1.0000
0.9998
0.9996
0.9994
0.9992
0.9990
2.7
Line Regulation
V =3.3V
IN
V = 5.0V
IN
V = 5.5V
IN
V =3.6V
IN
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
0
0.8
1
1.8
2
0
0.8
1
May 2007
5
1.8
2
0.2
0.4
0.6
1.2
1.4
1.6
0.2
0.4
0.6
1.2
1.4
1.6
M9999-051707
1.8
2
0.2
0.4
0.6
0.8
1.2
1.4
1.6
1.8
0.2
0.4
0.6
1.2
1.4
1.6
0.2
0.4
0.6
1.2
1.4
1.6
65
50
1.8
2
0.2
0.4
0.6
1.2
1.4
1.6
0.2
0.4
0.6
1.2
1.4
1.6
0.2
0.4
0.6
1.2
1.4
1.6
1.8
2
0.2
0.4
0.6
0.8
1.2
1.4
1.6
1.8
0.2
0.4
0.6
0.8
1.2
1.4
1.6
1.8
0.2
0.4
0.6
1.2
1.4
1.6
65
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