MPS MP2136 2.5v to 6v input, 2mhz, 1a synchronous step-down converter Datasheet

MP2136
2.5V to 6V Input, 2MHz, 1A
Synchronous Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2136 is a 2MHz 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 LiPolymer battery.
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The MP2136 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.
2MHz 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 6-pin, QFN6 2mm×2mm
package
APPLICATIONS
The MP2136 is available in a 6-pin, QFN6
2mm×2mm package.
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Cellular Phones
Microprocessors and DSP Core Supplies
PDAs and Smart Phones
MP3 and Portable Media Players
Digital Still and Video Cameras
Portable Instruments
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
Efficiency vs.
Output Current
VIN
2.5V - 6V
OFF ON
EN
C1
4.7uF
3 IN
4
SW
MP2136EG
2 EN
FB
1 NC
GND
L1
1.2uH
100
R1
300k
1%
6
5
R2
300k
1%
C2
10uF
VOUT
1.2V/1A
L=2.2uH Vo=1.2V
Vin=3.3V
90
80
EFFICIENCY (%)
U1
70
60
Vin=6V
Vin=5V
Vin=2.5V
50
40
30
20
10
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
OUTPUT CURRENT (A)
MP2136 Rev. 0.9
8/23/2010
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
Package
Top Marking
Free Air Temperature(TA)
MP2136EG
QFN6 (2mmx2mm)
6Q
–20°C to +85°C
* For Tape & Reel, add suffix –Z (eg. MP2136EG–Z).
For RoHS Compliant Packaging, add suffix –LF (eg. MP2136EG–LF–Z)
PACKAGE REFERENCE
TOP VIEW
NC
1
6
FB
EN
2
5
GND
VIN
3
4
SW
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
IN to GND .................................. –0.3V to +6.5V
SW to GND .......................... –0.3V to VIN + 0.3V
FB, EN to GND ............................. –0.3V to +6.5V
(2)
Continuous Power Dissipation. (TA = +25°C)
QFN6 (2mmx2mm) .................................... 2.5W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... –65°C to +150°C
QFN6 (2mmx2mm) ................. 50 ...... 12... °C/W
Recommended Operating Conditions
(3)
Supply Voltage VIN .............................2.5V to 6V
Output Voltage VOUT ...........................0.6V to 6V
Operating Junct.Temp. (TJ)...... –20°C to +125°C
MP2136 Rev. 0.9
8/23/2010
(4)
θJA
θJC
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. 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.
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS (5)
VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted.
Parameters
Condition
Supply Current
VEN = VIN, VFB = 0.65V
Shutdown Current
VEN = 0V, VIN = 6V
IN Under Voltage Lockout Threshold Rising Edge
IN Under Voltage Lockout Hysteresis
TA = +25°C
Regulated FB Voltage
–40°C ≤ TA ≤ +85°C
FB Input Bias Current
VFB = 0.65V
PFET Current Limit
Duty=100%
PFET On-Resistance
ISW = 100mA
NFET On-Resistance
ISW = –100mA
VEN = 0V; VIN = 6V
SW Leakage Current
VSW = 0V or 6V
EN High Threshold
–40°C ≤ TA ≤ +85°C
EN Low Threshold
–40°C ≤ TA ≤ +85°C
Internal Soft-Start Time
Oscillator Frequency
Thermal Shutdown Threshold
Hysteresis=20°C
Min
Typ
Max
350
1.8
0.582
0.576
-50
0.01
2.1
250
0.594
0.594
µA
1
2.3
0.606
0.612
50
µA
V
mV
V
V
nA
A
mΩ
mΩ
1
µA
1.5
200
150
–1
1.6
0.4
150
2
150
20
Units
V
V
µs
MHz
°C
°C
Note:
5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.
MP2136 Rev. 0.9
8/23/2010
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VOUT=1.2V, L=1.2uH, C2=10uF, TA=25°C, unless otherwise noted.
Steady State Operation
Steady State Operation
Steady State Operation
Vin=2.5V, Vo=1.2V, Io=0A
Vin=2.5V, Vo=1.2V, Io=1A
Vin=6V, Vo=1.2V, Io=0A
VOUT/AC
10mV/div.
VOUT/AC
10mV/div.
VOUT/AC
10mV/div.
VSW
2V/div.
VSW
2V/div.
IINDUCTOR
500mA/div.
VSW
5V/div.
IINDUCTOR
500mA/div.
IINDUCTOR
500mA/div.
200ns/div.
200ns/div.
200ns/div.
Steady State Operation
Start-up Through Enable
Start-up Through Enable
Vin=6V, Vo=1.2V, Io=1A
Vin=2.5V, Vo=1.2V, Io=0A
Vin=2.5V, Vo=1.2V, Io=1A
VOUT/AC
10mV/div.
VSW
5V/div.
IINDUCTOR
500mA/div.
VEN
2V/div.
VEN
2V/div.
VOUT
500mV/div.
VOUT
500mV/div.
VSW
2V/div.
VSW
2V/div.
IINDUCTOR
500mA/div.
IINDUCTOR
1A/div.
40us/div.
200ns/div.
40us/div.
Start-Up Through EN
Start-Up Through EN
Power-Down Through EN
Vin=6V, Vo=1.2V, Io=0A
Vin=6V, Vo=1.2V, Io=1A
Vin=2.5V, Vo=1.2V, Io=0A
VEN
2V/div.
VEN
2V/div.
VEN
2V/div.
VOUT
500mV/div.
VOUT
500mV/div.
VOUT
500mV/div.
VSW
5V/div.
VSW
5V/div.
VSW
2V/div.
IINDUCTOR
1A/div.
IINDUCTOR
500mA/div.
IINDUCTOR
500mA/div.
40us/div.
MP2136 Rev. 0.9
8/23/2010
40us/div.
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2s/div.
4
MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VOUT=1.2V, L=1.2uH, C2=10uF, TA=25°C, unless otherwise noted.
2.1
1.210
2.05
1.208
1.2
1.206
2
1.202
1.9
1.200
1.85
1.198
Vin=3.3V
Vin=5V
1.196
1.8
1.190
Falling
0.6
0.2
1.192
1.7
-40 -25 -10 5 20 35 50 65 80 95 110125
0.8
0.4
1.194
1.75
Rising
1
1.204
1.95
MP2136 Rev. 0.9
8/23/2010
1.4
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0
2.5
3
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3.5
4
4.5
5
5.5
6
5
MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
Pin #
1
Name
NC
2
EN
3
IN
4
SW
5
6
Description
No connection. Leave Pin1 disconnection.
Regulator Enable Control Input. Drive EN above 1.6V to turn on the part. Drive EN below
0.4V to turn it off.
Supply Input. Bypass to GND with a 4.7µF or bigger value ceramic capacitor.
Power Switch Output. Inductor connection to drains of the internal PFET and NFET
switches.
GND,
Exposed Ground. Connect exposed pad to ground plane for optimal thermal performance.
Pad
Feedback Input. Connect FB to the center point of the external resistor divider. The
FB
regulated feedback voltage is 0.6V.
MP2136 Rev. 0.9
8/23/2010
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
FUNCTIONAL BLOCK DIAGRAM
IN
EN
BIAS
&VOLTAGE
0.6V
REFERENCE
2MHz
OSCILLATOR
Slope Comp
OSC
ISW
Slope
Comp
150us
INTERNAL SS
FB
EAO
PWM
ISW
DH
PWM
CONTROL
LOGIC
PGATE
DL
MAIN
SWITCH
PCH
HIGH SIDE
GATE
DRIVE
0.6V
SW
1.2MEG 17pF
0.5pF
DL
LOW SIDE
GATE DRIVE
SYNCHRONOUS
RECTIFIER
NCH
GND
Figure 1— Functional Block Diagram
MP2136 Rev. 0.9
8/23/2010
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
FUNCTIONAL DESCRIPTION
MP2136 is a 2MHz constant frequency, current
mode, PWM step-down converter. The device
integrates both a main switch and a synchronous
rectifier, which provides high efficiency and
eliminates an external Schottky diode. It is ideal
for powering portable equipment that runs from a
single Li-lon or Li-Polymer battery.
The MP2136 can achieve 100% duty cycle. The
duty cycle D of a step-down converter is defined
as:
D = TON × fOSC × 100% ≈
VOUT
× 100%
VIN
Where,
Ton: Main Switch ON time
Fosc: Switching frequency (2MHz)
Vout: Output voltage
Vin: Input voltage
Peak Current Mode PWM Control
Slope compensated current mode PWM control
provides stable switching and cycle-by-cycle
current limit for superior load and line response
and protection of the internal main switch and
synchronous rectifier. The MP2136 switches at a
constant frequency (2MHz) and regulates the
output voltage. During each cycle the PWM
comparator modulates the power transferred to
the load by changing the inductor peak current
based on the feedback error voltage.
During normal operation, the main switch is
turned on for a certain time to ramp the inductor
current at each rising edge of the internal
oscillator, and switched off when the peak
inductor current is above the error voltage.
Dropout Operation
The MP2136 allows the main switch to remain on
for more than one switching cycle and increases
the duty cycle while the input voltage is dropping
close to the output voltage. When the duty cycle
reaches 100%, the main switch is held on
continuously to deliver current to the output up to
the PFET current limit. The output voltage then is
the input voltage minus the voltage drop across
the main switch and the inductor.
Short Circuit Protection
The MP2136 has short circuit protection. When
the output is shorted to ground, the oscillator
frequency is reduced to prevent the inductor
current from increasing beyond the PFET current
limit. The PFET current limit is also reduced to
lower the short-circuit current. The frequency and
current limit will return to the normal values once
the short circuit condition is removed and the
feedback voltage reaches 0.6V.
Maximum Load current
The MP2136 can operate down to 2.5V input
voltage, however the maximum load current
decreases at lower input due to large IR drop on
the main switch and synchronous rectifier. The
slope compensation signal reduces the peak
inductor current as a function of the duty cycle to
prevent sub-harmonic oscillations at duty cycles
greater than 50%. Conversely the current limit
increases as the duty cycle decreases.
When the main switch is off, the synchronous
rectifier will be turned on immediately and stay on
until the next cycle starts.
MP2136 Rev. 0.9
8/23/2010
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
APPLICATION INFORMATION
Output Voltage Setting
The external resistor divider sets the output
voltage. The feedback resistor R1 also sets the
feedback loop bandwidth with the internal
compensation capacitor.
Choose R1 around 300kΩ for optimal transient
response. R2 is then given by:
R2 =
R1
VOUT
−1
0 .6 V
Table 1—Resistor Selection vs. Output
Voltage Setting
VOUT
R1
R2
1.2V
300kΩ (1%)
300kΩ (1%)
1.5V
300kΩ (1%)
200kΩ (1%)
1.8V
300kΩ (1%)
150kΩ (1%)
2.5V
300kΩ (1%)
95.3kΩ (1%)
Inductor Selection
A 0.68µH to 10µH inductor with DC current
rating at least 25% higher than the maximum
load current is recommended for most
applications. For best efficiency, the inductor
DC resistance shall be <200mΩ. For most
designs, the inductance value can be derived
from the following equation:
L=
VOUT × (VIN − VOUT )
VIN × ∆IL × fOSC
Where ∆IL is the inductor ripple current. Choose
inductor ripple current approximately 30% of the
maximum load current, 1A.
The maximum inductor peak current is:
IL(MAX ) = ILOAD +
∆IL
2
Under light load conditions below 100mA, larger
inductance is recommended for improved
efficiency.
MP2136 Rev. 0.9
8/23/2010
Input Capacitor Selection
The input capacitor reduces the surge current
drawn from the input and switching noise from
the device. The input capacitor impedance at
the switching frequency shall be less than input
source impedance to prevent high frequency
switching current passing to the input. Ceramic
capacitors with X5R or X7R dielectrics are
highly recommended because of their low ESR
and small temperature coefficients. The input
capacitor absorbs the input switching current,
so it requires an adequate ripple current rating.
The RMS current through the input capacitor
can be estimated by:
ICIN = ILOAD ×
VOUT
V
× (1 − OUT )
VIN
VIN
The worse case condition occurs at VIN=2VOUT,
where:
ICIN =
ILOAD
2
For simplification, choose the input capacitor
whose RMS current rating greater than half of
the maximum load current.
For most applications, a 4.7µF capacitor is
sufficient.
Output Capacitor Selection
The output capacitor keeps output voltage
ripple small and ensures regulation loop stable.
The output capacitor impedance shall be low at
the switching frequency. Ceramic capacitors
with X5R or X7R dielectrics are recommended.
The output ripple ∆VOUT is approximately:
∆VOUT ≤
⎞
VOUT × (VIN − VOUT ) ⎛
1
⎟
× ⎜⎜ ESR +
VIN × fOSC × L
8 × fOSC × C3 ⎟⎠
⎝
For most applications, a 10uF capacitor is
sufficient.
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
PCB LAYOUT GUIDE
PCB layout is very important to achieve stable
operation. It is highly recommended to duplicate
EVB layout for optimum performance.
2)
If change is necessary, please follow these
guidelines and take Figure 2 for reference.
4) Route SW away from sensitive analog areas
such as FB.
1)
Keep the path of switching current short and
minimize the loop area formed by Input cap,
high-side MOSFET and low-side MOSFET.
2)
Bypass ceramic capacitors are suggested to
be put close to the VIN Pin.
5) Connect IN, SW, and especially GND
respectively to a large copper area to cool
the chip to improve thermal performance and
long-term reliability.
Top Layer
Ensure all feedback connections are short
and direct. Place the feedback resistors as
close to the chip as possible.
Bottom Layer
Figure 2—MP2136 Suggested Layout
MP2136 Rev. 0.9
8/23/2010
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MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER
PACKAGE INFORMATION
QFN6 (2mmX2mm)
1.90
2.10
0.30
0.40
PIN 1 ID
MARKING
0.20
0.30
1.90
2.10
PIN 1 ID
INDEX AREA
0.65
0.85
PIN 1 ID
SEE DETAIL A
1
6
1.25
1.45
0.65
BSC
3
4
TOP VIEW
BOTTOM VIEW
0.80
1.00
0.20 REF
PIN 1 ID OPTION A
0.30x45º TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.00
0.05
SIDE VIEW
DETAIL A
1.90
0.70
0.70
0.25
1.40
0.65
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.
MP2136 Rev. 0.9
8/23/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
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