MP2102
1.5MHz, 800mA Dual-Output
Synchronous Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2102 is a dual-output, internally
compensated, 1.5MHz fixed frequency PWM
step-down converter. It is ideal for powering
portable equipment from a single cell LithiumIon (Li+) Battery. Each channel of the MP2102
can supply 800mA of load current from a 2.5V
to 6V input voltage. Both output voltages can be
regulated as low as 0.6V.
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The device features integrated high-side
switches and synchronous rectifiers for high
efficiency step-down conversion without the
need for external Schottky diodes. With peak
current
mode
control
and
internal
compensation, the MP2102 can be stabilized
with ceramic capacitors and small inductors.
Fault condition protection includes cycle-bycycle current limiting and thermal shutdown.
The MP2102 is available in small 10-pin QFN
with exposed pad and 10-pin MSOP packages.
EVALUATION BOARD REFERENCE
Board Number
Dimensions
EV2102DQ-00B
2.2”X x 2.2”Y x 0.4”Z
Dual 800mA Outputs
Internal Power MOSFET Switches
Up to 95% Efficiency
1.5MHz Switching Frequency
1µA Shutdown Current
Stable with Low ESR Output Ceramic Capacitors
Thermal Shutdown
Cycle-by-Cycle Over Current Protection
Short Circuit Protection
Power-On Reset with Programmable Delay
2.5V to 6V Operating Input Range
Output Adjustable from 0.6V to 5.4V
Input Undervoltage Lockout
Available in 10-Pin QFN with Exposed Pad
and 10-Pin MSOP Packages.
APPLICATIONS
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DVD+/-RW Drive
Smart Phones
PDAs
Digital Cameras
Portable Instruments
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
Efficiency vs
Load Current
3
2
7
VOUT2
1.2V / 800mA
6
10
DLY
VIN
C4
1nF
EN1
EN2
PWROK
MP2102
SW2
FB2
SW1
GND
5
FB1
100
9
8
4
1
90 VOUT=1.8V
PWROK
VOUT1
1.8V / 800mA
EFFICIENCY (%)
VIN
2.4V to 6V
80
70
VOUT=1.2V
60
50
40
30
20
MP2102 Rev. 1.0
11/8/2006
10
100
LOAD CURRENT (mA)
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1000
1
MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
FB1
1
10
FB2
EN1
2
9
DLY
FB1
1
10
FB2
PWROK
EN1
2
9
DLY
VIN
3
8
PWROK
SW1
4
7
EN2
GND
5
6
SW2
VIN
8
3
SW1
4
7
EN2
GND
5
6
SW2
EXPOSED PAD
ON BACKSIDE
CONNECT TO
GROUND (PIN 5)
Part Number*
Package
Temperature
Part Number*
Package
Temperature
MP2102DQ
QFN10
(3mm x 3mm)
–40°C to +85°C
MP2102DK
MSOP10
–40°C to +85°C
*
For Tape & Reel, add suffix –Z (eg. MP2102DQ–Z)
For RoHS Compliant Packaging, add suffix –LF
(eg. MP2102DQ–LF–Z)
*
For Tape & Reel, add suffix –Z (eg. MP2102DK–Z)
For RoHS Compliant Packaging, add suffix –LF
(eg. MP2102DK–LF–Z)
ABSOLUTE MAXIMUM RATINGS (1)
Recommended Operating Conditions
VIN to GND .................................–0.3V to +6.5V
SW1/2 to GND ..................... –0.3V to VIN + 0.3V
FB1/2, OUT1/2, EN1/2 to GND...–0.3V to +6.5V
Operating Temperature............. –40°C to +85°C
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature.............. –65°C to +150°C
Supply Voltage VIN ............................. 2.5V to 6V
Output Voltage VOUT ....................... 0.6V to 5.4V
Operating Temperature .............–40°C to +85°C
Thermal Resistance
(3)
θJA
(2)
θJC
QFN10 .................................... 50 ...... 12... °C/W
MSOP10 ................................ 150 ..... 65... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
ELECTRICAL CHARACTERISTICS (4)
VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Supply Current
Shutdown Current
IN Under Voltage Lockout
Threshold
IN Under Voltage Lockout
Hysteresis
Output Line Regulation
Output Load Regulation
MP2102 Rev. 1.0
11/8/2006
Min
VEN = VIN, VFB = 0.62V
VEN = 0V, VIN = 6V
Rising Edge
VIN = 2.5V to 6V
ILOAD = 50mA to 500mA
1.7
Typ
Max
Units
750
0.01
1
µA
µA
2.0
2.3
V
100
mV
0.03
0.05
%/V
%/mA
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2
MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS (4) (continued)
VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
TA = +25°C
Regulated FB Voltage
–40°C ≤ TA ≤ +85°C
FB Input Bias Current
VFB = 0.62V
SW PFET On Resistance
ISW = 100mA
SW NFET On Resistance
ISW = –100mA
VEN = 0V, VIN = 6V
SW Leakage Current
VSW = 0V or 6V
Duty Cycle = 100%,
SW PFET Peak Current
Current Pulse Width < 1ms
Limit
Oscillator Frequency
Thermal Shutdown Trip
Threshold
PWROK Upper Trip
FB1/2/OUT1/2 with respect to the
Threshold
nominal value
PWROK Lower Trip
FB1/2/OUT1/2 with respect to the
Threshold
nominal value
PWROK Output Lower
ISINK = 5mA
Voltage
PWROK Deglitch Timer
C4 open
PWROK Startup Delay
C4 = 1nF
DLY Pull-Down Resistor
EN1/2 Trip Threshold
EN1/2 Trip Threshold
–40°C ≤ TA ≤ +85°C
EN Pull-Down Resistor
Min
0.588
0.582
–50
Typ
0.600
0.600
–2
0.4
0.3
–2
Max
0.612
0.618
+50
Units
+2
µA
V
nA
Ω
Ω
0.9
1.5
2.1
A
1.2
1.5
1.7
MHz
150
°C
10
%
–10
%
0.3
10
0.40
0.30
45
0.5
0.8
0.98
0.96
0.8
1.40
1.50
V
µs
ms
MΩ
V
V
MΩ
Note:
4) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.
PIN FUNCTIONS
Pin #
Name
Description
1
2
3
4
FB1
EN1
VIN
SW1
Feedback Input 1. Feedback input for output 1.
Enable Input 1. “High” input enables the switcher. It has an internal 800kΩ pull-down resistor.
Input Supply Pin.
Switch Node 1. Switch node to the inductors.
5
6
7
8
GND
SW2
EN2
PWROK
9
DLY
10
FB2
Ground Pin.
Switch Node 2. Switch node to the inductors.
Enable Input 2. “High” input enables the switcher. It has an internal 800kΩ pull-down resistor.
Power-On Reset Open Drain Output. Open drain output indicating that both outputs are
within 10% of the final regulation value. “Low” output indicates output is out of ±10% window.
PWROK is pulled down in shutdown.
Delay Set. The startup power on reset delay is proportional to the value of C4 connected to
this pin. It has an internal 800kΩ pull-down resistor.
Feedback Input 2. Feedback input for output 2.
MP2102 Rev. 1.0
11/8/2006
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MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VOUT1 = 1.8V, VOUT2 = 1.2V, C1 = C2 = C3 = 10µF, C4 = 1nF, L1 = L2 = 2.2µH, TA = +25°C, unless
otherwise noted.
Efficiency vs
Efficiency vs
Load Current
Load Current
100
100
VIN=3.3V
90 VOUT=1.8V
80
EFFICIENCY (%)
EFFICIENCY (%)
90
70
60
VIN=6.0V
50
40
30
20
70
10
100
LOAD CURRENT (mA)
50
40
20
1000
90
VOUT=1.8V
70
60
50
40
1000
1.5
1.2
0.9
0.6
0.3
30
20
10
100
LOAD CURRENT (mA)
0.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
INPUT VOLTAGE (V)
1000
Frequency vs
Temperature
Feedback Voltage vs
Temperature
0.610
FEEDBACK VOLTAGE (V)
1.8
FREQUENCY (MHz)
100
LOAD CURRENT (mA)
1.8
VOUT=2.5V
80
10
Frequency vs
Input Voltage
FREQUENCY (MHz)
100
1.5
1.2
0.9
0.6
0.3
0.0
-40
MP2102 Rev. 1.0
11/8/2006
VOUT=1.2V
60
30
Efficiency vs
Load Current
EFFICIENCY (%)
80
-10 20
50
80 110
TEMPERATURE (°C)
140
0.606
0.602
0.598
0.594
0.590
-40 -15 10 35 60 85 110 135
TEMPERATURE (°C)
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© 2006 MPS. All Rights Reserved.
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MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VOUT1 = 1.8V, VOUT2 = 1.2V, C1 = C2 = C3 = 10µF, C4 = 1nF, L1 = L2 = 2.2µH, TA = +25°C, unless
otherwise noted.
Output Voltage vs
Output Voltage vs
Load Current
Load Current
1.84
2.52
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2.54
2.50
2.48
2.46
2.44
0
200 400 600 800
LOAD CURRENT (mA)
1.82
1.80
1.78
1.76
1000
Output Voltage vs
Load Current
1000
1.6
SWITCH CURRENT (A)
OUTPUT VOLTAGE (V)
200 400 600 800
LOAD CURRENT (mA)
Peak Switch Current vs
Temperature
1.22
1.20
1.18
1.16
1.14
0
0
200 400 600 800
LOAD CURRENT (mA)
1.5
1.4
1.3
1.2
-40
1000
0
+40
+80
TEMPERATURE (OC)
+120
Current Limit vs
Duty Cycle
CURRENT LIMIT (A)
1.6
1.5
1.4
1.3
1.2
1.1
1.0
MP2102 Rev. 1.0
11/8/2006
30
40
50
60
70
80
DUTY CYCLE (%)
90
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MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VOUT1 = 1.8V, VOUT2 = 1.2V, C1 = C2 = C3 = 10µF, C4 = 1nF, L1 = L2 = 2.2µH TA = +25°C, unless
otherwise noted.
Enable Turn On
Enable Turn Off
VIN = 3.6V, EN = EN1 = EN2 = 4V,
ILOAD1 = ILOAD2 = 0.3A
with Resistive Load
VIN = 3.6V, EN = EN1 = EN2 = 4V,
ILOAD1 = ILOAD2 = 0.3A
with Resistive Load
PWROK
2V/div.
VOUT1
1V/div.
VOUT1
1V/div.
VOUT2
1V/div.
VOUT2
1V/div.
VIN = EN1 = 4.2V,
ILOAD1 = 0.8A
VOUT1
10mV/div.
EN
2V/div.
EN
2V/div.
PWROK
2V/div.
Heavy Load Ripple
VSW1
2V/div.
IL
0.5A/div.
400ns/div.
Input Ramp Up
Input Ramp Down
VIN = 4.2V, EN = EN1 = EN2 = 4V,
ILOAD1 = ILOAD2 = 0.3A
with Resistive Load
VIN = 4.2V, EN = EN1 = EN2 = 4V,
ILOAD1 = ILOAD2 = 0.3A
with Resistive Load
VSW
5V/div.
VOUT2
2V/div.
VOUT1
1V/div.
VOUT1
1V/div.
1ms/div.
VIN = 3.6V, ILOAD1 = 0.45A,
with Resistive Load
VOUT1
2V/div.
VIN
2V/div.
VIN
2V/div.
VOUT2
2V/div.
Over Current Protection
IL
0.5A/div.
1ms/div.
PWROK Off vs.
Short Output
Load Transient
VIN = 4.2V, ILOAD1 = ILOAD2 = 0.3A
with Resistive Load and VOUT2
Forced to Short
VIN = 4.2V, ILOAD1 = 0A to 0.8A Step
with Resistive Load
VOUT1
0.1V/div.
PWROK
2V/div.
VOUT1
1V/div.
IOUT1
0.5A/div.
VOUT2
0.5V/div.
MP2102 Rev. 1.0
11/8/2006
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© 2006 MPS. All Rights Reserved.
6
MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
OPERATION
The MP2102 is a dual-channel constant
frequency current mode PWM step-down
converter. The MP2102 is optimized for low
voltage, Li-Ion battery powered applications
where high efficiency and small size are critical.
The MP2102 uses an external resistor divider to
set the output voltage from 0.6V to 5.4V. The
device integrates both a main switch and a
synchronous rectifier which provides high
efficiency and eliminates the need for an
external Schottky diode.
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 MP2102 switches at a constant frequency
(1.5MHz) 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.
When the main switch is off, the synchronous
rectifier will be turned on immediately and stay
on until the next cycle starts. The maximum
duty cycle of the MP2102 is around 90%,
therefore the maximum achievable output
voltage is 90% of the input voltage minus the
voltage drop across the main switch and the
inductor.
MP2102 Rev. 1.0
11/8/2006
Short Circuit Protection
The MP2102 has an independent short circuit
protection for each channel. When the output is
shorted to ground, the valley current limit
control is activated; the next cycle of turning on
the main switch will not start until the inductor
current has dropped to below 300mA. The
control mechanism will return to normal once
the feedback voltage reaches 0.3V.
Output Power Good Indication
The open-drain pin PWROK is used to monitor
the output condition. When the voltages of both
outputs are within ±10% of the expected value,
the open-drain device will turn off, floating the
PWROK pin. When at least one of the outputs
is outside of ±10% window, the PWROK will be
pulled “LOW”.
Power-On Reset Delay
The MP2102 has a programmable power on
reset delay. Changing the value of the capacitor
at the DLY pin sets the delay time. See
Programming
PWROK
Delay
in
the
Applications Information section.
Maximum Load Current
The MP2102 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.
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7
MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
BLOCK DIAGRAMS
BUCK1
DLY
PWROK
DC-DC
CORE
PGD
MONITOR
EN1
POR
EN2
BG
REFERENCE
BUCK2
OSC
DC-DC
CORE
SHORT
DETECTION
Figure 1—Dual Buck Functional Block Diagram
VIN
EN1/2
ICS
0.6V
SLOPE COMP
+
EAMP
FB1/2
+
IAMP
10X
-CURRENT
SENSE AMP
BIAS &
VOLTAGE
REFERENCE
EAO
PWMCMP
+
+
PWM
DH
--
MAIN
SWITCH
(PCH)
-PWM
CONTROL
LOGIC
RC
17pF
1.5MHz
OSCILLATOR
OSC
SW1/2
SYNCHRONOUS
RECTIFIER
(NCH)
DL
GND
Figure 2—DC-DC Core Functional Block Diagram
MP2102 Rev. 1.0
11/8/2006
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© 2006 MPS. All Rights Reserved.
8
MP2102 – 1.5MHz, 800mA DUAL-OUTPUT SYNCHRONOUS STEP-DOWN CONVERTER
APPLICATION INFORMATION
Output Voltage Setting
Please reference the schematic on the front
page. The external resistor divider sets the
output voltage. The top feedback resistor RTOP
also sets the feedback loop bandwidth with the
internal compensation capacitor (see Typical
Application circuit).
Choose RTOP around 300kΩ for optimal
transient response. The bottom feedback
resistor RBOT is then given by:
R BOT =
R TOP
VOUT
−1
0 .6 V
Where RTOP is either R1 or R3, and RBOT is
either R2 or R4.
Table 1—Resistor Selection vs. Output
Voltage Setting
VOUT
RTOP
RBOT
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 (L1, L2)
A 1µH 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
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