MP2128
2.5V-6V Input, 3MHz, 1A
Synchronous Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
The MP2128 is a 3MHz constant frequency,
current mode, PWM step-down converter with
integrated main switch and synchronous
rectifier that is ideal for powering portable
equipment that runs from a single Li-Ion or Li-
Polymer battery.
The MP2128 can supply up to 1A load current
from a 2.5V to 6V input voltage. The output
voltage can be as low as 0.6V.
Additional features include <1µA shutdown
current, internal soft-start, cycle-by-cycle over
current protection, short circuit protection, and
thermal shutdown.
The MP2128 is available in low profile (1.5mm)
5-pin SOT23 and 8-pin, QFN8 2mm×2mm
packages.
FEATURES
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High Efficiency: Up to 95%
3MHz Constant Switching Frequency
1A Available Load Current
2.5V to 6V Input Voltage Range
Output Voltage as Low as 0.6V
Current Mode Control
Cycle-by-Cycle Over Current Protection
Short Circuit Protection
Thermal Shutdown
<1µA Shutdown Current
Internal Soft-Start
Space Saving 5-Pin SOT23 Package and
8-pin, QFN8 2mm×2mm package
Cellular Phones
Microprocessors and DSP Core Supplies
PDAs and Smart Phones
MP3 and Portable Media Players
Digital Still and Video Cameras
Portable Instruments
APPLICATIONS
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
U1
2.5V--6V
VIN
3
IN
SW
SW
6
5
R1
200k
1%
1.8V 1A
VOUT
MP2128DG
OFF ON
8
EN
FB
1
R2
100k
1%
7
NC
AGND
2
PGND
4
MP2128 Rev. 0.9
7/20/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
1
MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
MP2128DT
Part Number**
MP2128DG
Package
SOT23
Package
QFN8(2mmx2mm)
Top Marking
2H
Top Marking
2H
Temperature
–40°C to +85°C
Temperature
–40°C to +85°C
* For Tape & Reel, add suffix –Z (eg. MP2128DT–Z). For RoHS Compliant Packaging, add suffix –LF (eg.
MP2128DT–LF–Z)
** For Tape & Reel, add suffix –Z (eg. MP2128DG–Z). For RoHS Compliant Packaging, add suffix –LF (eg.
MP2128DG–LF–Z)
PACKAGE REFERENCE
TOP VIEW
EN
GND
SW
1
2
3
5
FB
FB
AGND
IN
1
2
3
4
TOP VIEW
8
7
6
5
EN
NC
SW
SW
SOT23
ABSOLUTE MAXIMUM RATINGS
(1)
IN to GND ..................................
–
0.3V to +6.5V
SW to GND ..........................
–
0.3V to V
IN
+ 0.3V
FB, EN to GND .............................
–
0.3V to +6.5V
Continuous Power Dissipation. (T
A
= +25°C)
(2)
SOT23 ..................................................... 0.57W
QFN8 (2mmx2mm) .................................... 2.5W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature...............
–
65°C to +150°C
Recommended Operating Conditions
Supply Voltage V
IN
.............................2.5V to 6V
Output Voltage V
OUT
...........................0.6V to 6V
Operating Temperature..............
–
40°C to +85°C
MARKING
4
IN
PGND
QFN8
Thermal Resistance
(4)
SOT23 ................................... 220 .... 110..
°C/W
QFN8 (2mmx2mm) ................. 50 ...... 12...
°C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature T
J
(MAX), the junction-to-
ambient thermal resistance
θ
JA
, and the ambient temperature
T
A
. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by P
D
(MAX) = (T
J
(MAX)-T
A
)/θ
JA
. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
θ
JA
θ
JC
(3)
MP2128 Rev. 0.9
7/20/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
2
MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS
(5)
V
IN
= V
EN
= 3.6V, T
A
= +25°C, unless otherwise noted.
Parameters
Supply Current
Condition
V
EN
= V
IN
, V
FB
= 0.65V
1.8
0.582
0.576
-50
Min
Typ
350
0.01
2.1
250
0.594
0.594
1.5
200
150
–1
1.6
0.4
2.4
100
2.8
150
3.2
1
1
2.3
0.606
0.612
50
Max
Units
µA
µA
V
mV
V
V
nA
A
mΩ
mΩ
µA
V
V
µs
MHz
°C
Shutdown Current
V
EN
= 0V, V
IN
= 6V
IN Under Voltage Lockout Threshold Rising Edge
IN Under Voltage Lockout Hysteresis
T
A
= +25°C
Regulated FB Voltage
–40°C
≤
T
A
≤
+85°C
FB Input Bias Current
V
FB
= 0.65V
PFET Current Limit
Duty=100%
PFET On-Resistance
I
SW
= 100mA
NFET On-Resistance
I
SW
= –100mA
V
EN
= 0V; V
IN
= 6V
SW Leakage Current
V
SW
= 0V or 6V
EN High Threshold
–40°C
≤
T
A
≤
+85°C
EN Low Threshold
–40°C
≤
T
A
≤
+85°C
Internal Soft-Start Time
Oscillator Frequency
Thermal Shutdown Threshold
Hysteresis=20°C
Note:
5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.
MP2128 Rev. 0.9
7/20/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
3
MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
=6V, V
OUT
=1.8V, L=1.2µH, C2=10µF, T
A
=25°C, unless otherwise noted.
Efficiency vs. Load Current
95
90
V
OUT
/AC
20mV/div.
5V to 3.4V
Steady State Operation
I
OUT
=0A
V
OUT
/AC
20mV/div.
Steady State Operation
I
OUT
=1A
4.2V to 3.4V
EFFICIENCY (%)
85
80
75
70
3.3V to 1.8V
V
SW
5V/div.
V
SW
5V/div.
I
INDUCTOR
1A/div.
0 100 200 300 400 500 600 700 800 9001000
I
INDUCTOR
1A/div.
200ns/div.
200ns/div.
LOAD CURRENT ( mA )
Start-up Through Enable
I
OUT
=0A
V
EN
5V/div.
V
OUT
1V/div.
V
SW
5V/div.
V
EN
5V/div.
V
OUT
1V/div.
V
SW
5V/div.
Start-up Through Enable
I
OUT
=1A
V
EN
5V/div.
V
OUT
1V/div.
V
SW
5V/div.
Power-down Through Enable
I
OUT
=0A
I
INDUCTOR
1A/div.
I
INDUCTOR
1A/div.
I
INDUCTOR
1A/div.
2s/div.
Power-down Through Enable
I
OUT
=1A
V
EN
5V/div.
V
OUT
1V/div.
I
INDUCTOR
200mA/div.
V
OUT
/AC
100mV/div.
Load Transient
Load Step: 100mA-400mA,
V
IN
=4.2V, V
OUT
=3.4V
V
OUT
/AC
50mV/div.
V
SW
5V/div.
I
INDUCTOR
1A/div.
I
LOAD
200mA/div.
I
INDUCTOR
500mA/div.
1ms/div.
MP2128 Rev. 0.9
7/20/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
4
MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
SOT23
Pin #
1
2
3
4
5
QFN
Pin #
8
2,4
5,6
3
1
Name
EN
GND
SW
IN
FB
Description
Regulator Enable Control Input. Drive EN above 1.6V to turn on the part. Drive EN
below 0.4V to turn it off.
Ground.
Power Switch Output. Inductor connection to drains of the internal PFET and
NFET switches.
Supply Input. Bypass to GND with a 4.7µF or bigger value ceramic capacitor.
Feedback Input. Connect FB to the center point of the external resistor divider. The
regulated feedback voltage is 0.6V.
FUNCTIONAL BLOCK DIAGRAM
Figure 1— Functional Block Diagram
MP2128 Rev. 0.9
7/20/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
5
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