MIC4744
4 MHz Dual 2A Integrated Switch
Buck Regulator
General Description
The Micrel MIC4744 is a high efficiency dual PWM buck
(step-down) regulator that provides dual 2A current output.
The MIC4744 operates at 4MHz. A proprietary internal
compensation technique allows a closed loop bandwidth of
over 200kHz.
The low on-resistance internal P-Channel MOSFET of the
MIC4744 allows efficiencies over 90%, reduces external
components count and eliminates the need for an
expensive current sense resistor.
The MIC4744 operates from 2.9V to 5.5V input and the
output can be adjusted down to 0.6V. The device can
operate with a maximum duty cycle of 100% for use in low-
dropout conditions.
The MIC4744 is available in the exposed pad 16-pin
3mm x 3mm MLF
®
and ETSSOP-16 packages with
junction operating temperature ranging from –40°C to
+125°C.
All support documentation can be found on Micrel’s web
site at: www.micrel.com.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
2.9 to 5.5V supply voltage
4MHz PWM mode
2A Dual output
Greater than 90% efficiency
100% maximum duty cycle
Output voltage adjustable down to 0.6V
Ultra-fast transient response
Ultra-small external components
Stable with a 0.47µH inductor and a 10µF output
capacitor
Fully integrated 2A MOSFET switches
Micro-power shutdown
Thermal shutdown and current limit protection
Available in 3mm x 3mm 16-pin MLF
®
and 16-pin
TSSOP packages
–40°C to +125°C junction temperature range
Broadband: xDSL modems
Automotive satellite radios
HD STB, DVD/TV recorder
Computer peripherals: printers and graphic cards
FPGA/ASIC
General point of load
Applications
Typical Application
5.0Vin 3.3Vout Efficiency
100
98
96
EFFICIENCY (%)
94
92
90
88
86
84
82
80
0.0
0.4
0.8
1.2
1.6
2.0
OUTPUT CURRENT (A)
2A 4MHz Dual 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
March 2009
1
M9999-030209-C
Micrel, Inc.
MIC4744
Ordering Information
Part Number
MIC4744YML
MIC4744YTSE
Note:
MLF is a GREEN RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
®
Output Voltage
Adj.
Adj.
Junction Temp. Range
–40° to +125°C
–40° to +125°C
Package
16-Pin 3mm x 3mm MLF
16-Pin EPAD TSSOP
®
Lead Finish
Pb-Free
Pb-Free
Pin Configuration
16-Pin 3mm x 3mm MLF
®
(YML)
16-Pin EPAD-TSSOP (YTSE)
March 2009
2
M9999-030209-C
Micrel, Inc.
MIC4744
Pin Description
Pin Number
®
(MLF )
1
2
(1)
3,4
5
Pin Number
(EPAD-TSSOP)
7
8
(1)
9,10
11
Pin Name
FB2
EN2
SW2
PGND2
Pin Function
Feedback for output 2 (Input). Input to the error amplifier, connect to the
external resistor divider network to set the output voltage.
Enable for output 2 (Input). Logic level low, will shutdown the device, reducing
the current draw to less than 5µA (both EN1 and EN2 are low).
Switch for output 2 (Output): Internal power P-Channel MOSFET output switch
Power Ground for output 2. Provides the ground return path for the high-side
drive current.
PGND1 pin and PGND2 pin are internally connected by anti-parallel diodes.
6,15
5,12
VIN2
Supply Voltage for output 2 (Input): Supply voltage for the source of the
internal P-Channel MOSFET and driver. Requires bypass capacitor to GND.
VIN1 pins and VIN2 pins are internally connected by anti-parallel diodes.
7,14
4,13
VIN1
Supply Voltage for output 1 (Input): Supply voltage for the source of the
internal P-Channel MOSFET and driver. Requires bypass capacitor to GND.
VIN1 pins and VIN2 pins are internally connected by anti-parallel diodes.
8
14
PGND1
Power Ground for output 1. Provides the ground return path for the
high-side drive current.
PGND1 pin and PGND2 pin are internally connected by anti-parallel diodes.
9,10
11
(1)
12
13
16
EPAD
Note:
1. Do not float Enable Input.
15,16
1
(1)
2
3
6
EPAD
SW1
EN1
FB1
SGND
BIAS
GND
Switch for output 1 (Output): Internal power P-Channel MOSFET output switch
Enable for output 1 (Input). Logic level low, will shutdown the device, reducing
the current draw to less than 5µA (both EN1 and EN2 are low).
Feedback for output 1 (Input). Input to the error amplifier, connect to the
external resistor divider network to set the output voltage.
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. Biased through a 10Ω resistor to VIN.
Connect to ground.
March 2009
3
M9999-030209-C
Micrel, Inc.
MIC4744
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ......................................... -0.3V to +6V
Output Switch Voltage (V
SW1,
V
SW2
).................. -0.3V to +6V
Output Switch Current (I
SW1,
I
SW2
)………...Internally Limited
Input Voltage (V
EN
), (V
FB
), (V
BIAS
) ...................... -0.3V to V
IN
Storage Temperature (T
s
) .........................–60°C to +150°C
Junction Temperature ................................................ 150°C
Lead Temperature (soldering, 10sec.)....................... 260°C
ESD Rating
(3)
................................................................. 2KV
Operating Ratings
(2)
Supply Voltage (V
IN
)..................................... +2.9V to +5.5V
Logic Input Voltage (V
EN
) ....................................... 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
MLF
®
(θ
JA
)..........................................................60°C/W
EPAD TSSOP (θ
JA
)............................................35°C/W
Electrical Characteristics
(4)
V
IN
= V
EN
= 3.6V; L = 1.0µH; 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
Switching Phase
Enable Threshold
Enable Hysteresis
Enable Input Current
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
IN
= 5.5V
V
FB
= 0.9 * V
NOM
(not switching); V
IN
= 3.6V
V
EN
= 0V
±
2% (over temperature) I
LOAD
= 100µA
V
FB
= 0.9 * V
NOM
V
IN
= 2.9V to 5.5V; I
LOAD
= 100µA
20mA < I
LOAD
< 2A
V
FB
≤
0.9 * V
NOM
I
SW
= 50mA V
FB
=GND
Min
2.9
2.45
Typ
2.6
100
1.4
1.0
1.6
Max
5.5
2.7
3.0
10
0.612
Units
V
V
mV
mA
mA
µA
V
nA
A
%
%
%
0.588
2.5
0.6
1
4.3
0.07
0.2
100
155
3.0
0.5
3.8
180
0.9
55
0.1
153
18
2
1.3
4.4
mΩ
MHz
°C
V
mV
µA
°C
°C
March 2009
4
M9999-030209-C
Micrel, Inc.
MIC4744
Typical Characteristics
3.3Vin 1.0Vout Efficiency
76
74
72
76
74
72
5.0Vin 1.0Vout Efficiency
80
78
76
3.3Vin 1.2Vout Efficiency
EFFICIENCY (%)
EFFICIENCY (%)
70
68
66
64
62
60
58
56
0
0.4
0.8
1.2
1.6
2
3.0Vin
3.3Vin
3.6Vin
70
68
66
64
62
60
58
56
0
0.4
0.8
1.2
1.6
2
4.5Vin
5.0Vin
5.5Vin
EFFICIENCY (%)
74
72
70
68
66
64
62
60
0
0.4
0.8
1.2
1.6
2
3.0Vin
3.3Vin
3.6Vin
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
5.0Vin 1.2Vout Efficiency
80
78
76
84
82
80
3.3Vin 1.5Vout Efficiency
84
82
80
5.0Vin 1.5Vout Efficiency
EFFICIENCY (%)
74
72
70
68
66
64
62
60
0
0.4
0.8
1.2
1.6
2
4.5Vin
5.0Vin
5.5Vin
EFFICIENCY (%)
78
76
74
72
70
68
66
64
0
0.4
0.8
1.2
1.6
2
3.0Vin
3.3Vin
3.6Vin
EFFICIENCY (%)
78
76
74
72
70
68
66
64
0
0.4
0.8
1.2
1.6
2
4.5Vin
5.0Vin
5.5Vin
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
3.3Vin 1.8Vout Efficiency
88
86
84
88
86
84
5.0Vin 1.8Vout Efficiency
94
92
90
3.3Vin 2.5Vout Efficiency
EFFICIENCY (%)
EFFICIENCY (%)
80
78
76
74
72
70
68
0
0.4
0.8
1.2
1.6
2
3.0Vin
3.3Vin
3.6Vin
80
78
76
74
72
70
68
0
0.4
0.8
1.2
1.6
2
4.5Vin
5.0Vin
5.5Vin
EFFICIENCY (%)
82
82
88
86
84
82
80
78
76
74
0
0.4
0.8
1.2
1.6
2
3.0Vin
3.3Vin
3.6Vin
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
5.0Vin 2.5Vout Efficiency
94
92
90
96
94
92
5.0Vin 3.3Vout Efficiency
1.010
Load Regulation
EFFICIENCY (%)
86
84
82
80
78
76
74
0.0
0.4
0.8
1.2
1.6
2.0
4.5Vin
5.0Vin
5.5Vin
EFFICIENCY (%)
88
90
88
86
84
82
80
78
76
0.0
0.4
0.8
1.2
1.6
2.0
4.5Vin
5.0Vin
5.5Vin
OUTPUT VOLTAGE (V)
1.005
1.000
0.995
Vin=3.3V
0.990
0
0.4
0.8
1.2
1.6
2
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
March 2009
5
M9999-030209-C
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