MIC4722
3mm x 3mm 2.7MHz 3A PWM Buck Regulator
General Description
The Micrel MIC4722 is a high efficiency PWM buck (step-
down) regulator that provides up to 3A of output current.
The MIC4722 operates at 2.7MHz that makes it suitable
for next generation XDSL modems requiring operating
frequencies in excess of 2.4MHz and has proprietary
internal compensation that allows a closed loop bandwidth
of over 200KHz.
The low on-resistance internal p-channel MOSFET of the
MIC4722 allows efficiencies over 92%, reduces external
components count and eliminates the need for an
expensive current sense resistor.
The MIC4722 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 MIC4722 is available in the exposed pad 12-pin
3mm x 3mm MLF
®
package with a junction operating
range from –40°C to +125°C.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
2.7 to 5.5V supply voltage
2.7MHz PWM mode
Output current to 3A
>92% efficiency
100% maximum duty cycle
Adjustable output voltage option down to 1V
Ultra-fast transient response
Ultra-small external components
Stable with a 0.47µH inductor and a 4.7µF output
capacitor
Fully integrated 3A 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
Applications
•
•
•
•
•
5V or 3.3V Point of Load Conversion
Telecom/Networking Equipment
Set Top Boxes
Storage Equipment
Video Cards
Typical Application
MIC4722
3A 2.7MHz 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 2010
M9999-051410-C
Micrel, Inc.
MIC4722
Ordering Information
Part Number
MIC4722YML
Note:
MLF® is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Voltage
Adj.
Junction Temp. Range
–40° to +125°C
Package
12-Pin 3x3 MLF
®
Lead Finish
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
12-Pin 3mm x 3mm MLF
®
(ML)
Pin Description
Pin Number
1,12
2,11
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
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 2010
2
M9999-051410-C
Micrel, Inc.
MIC4722
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
Junction Temperature ................................................ 150°C
EDS Rating
(3)
.................................................................. 2kV
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
3x3 MLF-12 (θ
JA
) ...............................................60°C/W
Electrical Characteristics
(4)
V
IN
= V
EN
= 3.6V; L = 0.47µH; 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. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
Condition
(turn-on)
V
FB
= 0.9 * V
NOM
(not switching)
V
EN
= 0V
±
1% I
LOAD
= 100mA
±
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
< 3A
V
FB
≤
0.4V
I
SW
= 50mA V
FB
= 0.7V
FB_NOM
(High Side Switch)
Min
2.7
2.45
Typ
2.55
100
570
2
Max
5.5
2.65
900
10
1.01
1.02
Units
V
V
mV
µA
µA
V
nA
A
%
%
%
0.99
0.98
1
1
3.5
5
0.07
0.2
100
95
2.4
0.5
2.7
0.85
50
0.1
±7
2
±10
250
200
300
3.0
1.3
mΩ
MHz
V
mV
µA
%
Ω
°C
°C
I
PGOOD
= 500µA
145
150
25
May 2010
3
M9999-051410-C
Micrel, Inc.
MIC4722
Typical Characteristics
96
94
92
90
88
86
84
82
80
78
76
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
MIC4722
3.3V
OUT
Efficiency
4.5V
IN
5V
IN
94
92
90
88
86
84
82
80
0
MIC4722
2.5V
OUT
Efficiency
4.5V
IN
100
98
96
94
92
90
88
86
84
82
MIC4722
2.5V
OUT
Efficiency
3V
IN
3.3V
IN
3.6V
IN
5.5V
IN
5V
IN
5.5V
IN
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
80
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
90
88 4.5V
IN
5V
IN
86
84
82
80
5.5V
IN
78
76
74
72
70
68
66
64
62
60
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
MIC4722
1.8V
OUT
Efficiency
3
96
94
92 3V
IN
3.3V
IN
90
88
86
84
3.6V
IN
82
80
78
76
74
72
70
68
66
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
MIC4722
1.8V
OUT
Efficiency
3
86
84
82
80
78
76
74
72
70
68
66
64
0
MIC4722
1.5V
OUT
Efficiency
4.5V
IN
5V
IN
5.5V
IN
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
92
90
3V
IN
88
3.3V
IN
86
84
82
3.6V
IN
80
78
76
74
72
70
68
66
64
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
MIC4722
1.5V
OUT
Efficiency
3
90
88
86
84
82
80
78
76
74
72
70
68
66
64
62
60
0
MIC4722
1.2V
OUT
Efficiency
4.5V
IN
5V
IN
5.5V
IN
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
90
88
86 3V
IN
84
3.3V
IN
82
80
78
76
3.6V
IN
74
72
70
68
66
64
62
60
0
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
MIC4722
1.2V
OUT
Efficiency
3
78
76
74
72
70
68
66
64
62
60
0
MIC4722
1V
OUT
Efficiency
4.5V
IN
5V
IN
5.5V
IN
84
82
80
78
76
74
72
70
68
66
64
0
MIC4722
1V
OUT
Efficiency
3V
IN
OUTPUT VOLTAGE (V)
1.010
Load Regulation
3.3V
IN
1.005
3.6V
IN
1.000
0.995
3.3V
V
IN
= 3.3V
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
0.5
1
1.5
2
2.5
OUTPUT CURRENT (A)
3
0.990
0
May 2010
4
M9999-051410-C
Micrel, Inc.
MIC4722
Typical Characteristics (cont.)
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
SUPPLY VOLTAGE (V)
Line Regulation
1.010
1.008
1.006
1.004
1.002
1.000
0.998
0.996
0.994
Feedback Voltage
vs. Temperature
3.2
3.1
3.0
2.9
2.8
2.7
2.6
2.5
Frequency
vs. Temperature
0.992 V = 3.3V
IN
0.990
20 40 60 80
TEMPERATURE (°C)
2.4
2.3 V = 3.3V
IN
2.2
20 40 60 80
TEMPERATURE (°C)
1.2
1.0
0.8
0.6
0.4
0.2
Feedback Voltage
vs. Supply Voltage
800
700
600
500
400
300
200
Quiescent Current
vs. Supply Voltage
120
115
110
105
100
95
90
85
80
75
70
2.7
R
DSON
vs. Supply Voltage
V
EN
= V
IN
0
012345
SUPPLY VOLTAGE (V)
100
V
EN
= V
IN
0
0123456
SUPPLY VOLTAGE (V)
3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
160
140
120
100
80
60
40
20
0
R
DSON
vs. Temperature
1.2
1.0
0.8
0.6
0.4
0.2
Enable Threshold
vs. Supply Voltage
1.2
1.0
0.8
0.6
0.4
0.2
Enable Threshold
vs. Temperature
V
IN
= 3.3V
20 40 60 80
TEMPERATURE (°C)
0
2.7
3.2
3.7
4.2
4.7
SUPPLY VOLTAGE (V)
0
V
IN
= 3.3V
20 40 60 80
TEMPERATURE (°C)
May 2010
5
M9999-051410-C
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