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TM
MP1543
1.5A, 500KHz Synchronous Rectified Step-up Converter
The Future of Analog IC Technology
TM
DESCRIPTION
The MP1543 is a highly efficient, synchronous, fixed frequency, current-mode step-up converter with output to input disconnect, inrush current limiting and internal soft-start. It includes an error amplifier, ramp generator, comparator, N-Channel switch and P-Channel synchronous rectified switch (which greatly improves efficiency). The output disconnect feature allows the output to be completely isolated from the input in shutdown mode. The 500KHz switching frequency allows for smaller external components producing a compact solution for a wide range of load currents. The internal compensation and soft-start minimizes the external component count and limits the inrush current during startup. The MP1543 regulates the output voltage up to 6V and provides up to 400mA from a 2-cell AA with a 3.3V output. The MP1543 is offered in a thin SOT23-5 package.
FEATURES
* * * * * * * * * * * * * * * Over 90% Efficiency Output to Input Disconnect at Shutdown Mode Internal Synchronous Rectifier Inrush Current Limiting and Internal Soft-Start Internal Compensation 1.5A Typical Switch Current Limit 500KHz Fixed Switching Frequency Zero Current Shutdown Mode Thermal Shutdown 5-Pin TSOT-23 Package MP3 Players Handheld Computers and PDAs Digital Still and Video Cameras External Modems Small LCD Displays
APPLICATIONS
"MPS" and "The Future of Analog IC Technology" are Trademarks of Monolithic Power Systems, Inc.
EVALUATION BOARD REFERENCE
Board Number EV1543DJ-01A Dimensions 2.4"X x 2.4"Y x 0.4"Z
TYPICAL APPLICATION
Efficiency vs Load Current
VIN
1.8V - 3.2V
100 90
EFFICIENCY (%)
4 SW OUT 3
VIN=3V
80 70 60 50 40 30 1 VOUT=3.3V 10 100 LOAD CURRENT (mA) 1000 VIN=2.4V VIN=1.8V
EN
5
EN
MP1543
GND 2 FB 1
VOUT 3.3V 400mA
MP1543-EC01
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
1
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
PACKAGE REFERENCE
TOP VIEW
FB GND OUT 1 5 EN
ABSOLUTE MAXIMUM RATINGS (1)
All Pins........................................ -0.3V to +6.5V Storage Temperature ..............-65C to +150C
Recommended Operating Conditions
(2)
2 3
Supply Voltage VIN ............................. 1.8V to 6V Output Voltage VOUT .......................... 2.5V to 6V Operating Temperature .............-40C to +85C
B9YW
4 SW
MP1543_PD01-TSOT23-5
Thermal Resistance
(3)
TSOT23-5.............................. 220 .... 110.. 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.
JA
JC
Part Number* MP1543DJ *
Package TSOT23-5
Temperature -40C to +85C
For Tape & Reel, add suffix -Z (eg. MP1543DJ-Z) For Lead Free, add suffix -LF (eg. MP1543DJ-LF-Z)
ELECTRICAL CHARACTERISTICS
VEN = VOUT = 3.3V, TA = +25C, unless otherwise noted.
Parameter Startup Supply Voltage Output Voltage Range Supply Current (Shutdown) Supply Current Feedback Voltage Feedback Input Current Switching Frequency Maximum Duty Cycle EN Input Low Voltage EN Input High Voltage EN Pull Down Resistor Low-Side On Resistance Low-Side Current Limit High-Side On Resistance Thermal Shutdown
(4) (4)
Symbol Condition VST VOUT VEN = VOUT 0V, VSW = 5V VFB = 1.3V VFB VFB = 1.2V fSW DMAX ILOAD = 0mA RLOAD = 50
Min 1.5 2.5
Typ 1.6 1.7
Max 1.8 6.0
Units V V A A V nA KHz
1 350 1.2 50 500 80 1.4 1 85 90 0.4
% V V M m A m C C
RONLS ILIM RONHS
VOUT = 3.3V VOUT = 3.3V
300 1.5 500 160 30
Thermal Shutdown Hysteresis
Note: 4) Guaranteed by design, not tested.
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
2
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
Circuit on front page, VIN = 2.4V, VOUT = 3.3V, TA = +25C, unless otherwise noted.
Efficiency vs Load Current
100 90
EFFICIENCY (%)
Efficiency vs Load Current
100 90
EFFICIENCY (%)
Discontinuous Mode Operation
ILOAD = 25mA
VIN=3V
VIN=4.2V VIN=3.6V
VSW 2V/div. VOUT AC 10mV/div.
80 70 60 50 40 30 1 10 100 LOAD CURRENT (mA) 1000 VIN=2.4V VIN=1.8V
80 70 60 50 40 30 1 VIN=2.4V
VOUT=5V 10 100 LOAD CURRENT (mA)
IINDUCTOR 0.1A/div.
1000
MP1543-TPC03
MP1543-TPC01
MP1543-TPC02
Continuous Mode Operation
ILOAD = 400mA
Transient Response
ILOAD = 40mA to 400mA Step w/o Feed-Forward Capacitor
Transient Response
ILOAD = 40mA to 400mA Step with 220pF Feed-Forward Capacitor
VSW 2V/div. VOUT AC 50mV/div.
VOUT AC 100mV/div.
VOUT AC 100mV/div.
IINDUCTOR 0.2A/div.
ILOAD 0.2A/div.
ILOAD 0.2A/div.
MP1543-TPC04
MP1543-TPC05
MP1543-TPC06
Feedback Voltage vs Temperature
SWITCHING FREQUENCY (KHz)
Switching Frequency vs Temperature
540 530 520 510 500 490 480 470 460 -40 0 40 80 TEMPERATURE (C) 120
1.190
VEN 2V/div. VSW 2V/div.
1.186
FB VOLTAGE (V)
1.182 1.178 1.174 1.170 -40
VOUT 2V/div.
MP1543-TPC07
0 40 80 TEMPERATURE (C)
120
MP1543-TPC08
MP1543-TPC09
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
3
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Maximum Duty Cycle vs Temperature
88.10
MAX DUTY CYCLE (%)
Quiescent Current vs Temperature
380 370
CURRENT LIMIT (A)
Current Limit vs Duty Cycle
1.6
88.05 88.00 87.95 87.90 87.85 87.80 -40 0 40 80 TEMPERATURE (C) 120
360 350 340 330 320 310 300 -40 0 40 80 TEMPERATURE (C) 120
1.4
1.2
1.0
0.8
0
20
40 60 80 DUTY CYCLE (%)
100
MP1543-TPC10
MP1543-TPC11
MP1543-TPC12
PIN FUNCTIONS
Pin # 1 2 3 4 5 Name Description FB GND OUT SW EN Regulation Feedback Input. Connect to an external resistive voltage divider from the output to FB to set the output voltage. Ground. Supply Input for the MP1543. Connect to the output of the converter. Output Switching Node. SW is the drain of the internal low-side N-Channel MOSFET and high-side P-Channel MOSFET. Connect the inductor to SW to complete the step-up converter. Regulator On/Off Control Input. A logic high input (VEN > 1.4V) turns on the regulator. A logic low input (VEN < 0.4V) puts the MP1543 into low current shutdown mode.
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
4
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
OPERATION
UVLO REFERENCE VOLTAGE BIAS CURRENT THERMAL SHUTDOWN EN OUT
OSC 500KHz
CONTROL LOGIC SW
RAMP
+ CURRENT SENSE AMPLIFIER ERROR AMPLIFIER 1.2V
RS GND FB
MP1543_BD01
PWM COMPARATOR
Figure 1--Functional Block Diagram The MP1543 uses a 500KHz fixed-frequency, current-mode regulation architecture to regulate the output voltage. The MP1543 measures the output voltage through an external resistive voltage divider and compares that to the internal 1.2V reference to generate the error voltage. The current-mode regulator compares the error voltage to the inductor current to regulate the output voltage. The use of current-mode regulation improves transient response and control loop stability. When the MP1543 is disabled (EN = Low), both power switches are off. The body of the P-Channel MOSFET connects to SW and there is no current path from SW to OUT. Therefore, the output voltage discharges to ground. When the MP1543 is enabled (EN = High), the body of the P-Channel MOSFET connects to OUT and forms a forward diode from SW to OUT. Thus the output voltage rises up toward the input voltage. When output voltage crosses 1.6V the MP1543 starts the controller and regulates the output voltage to the target value. At the beginning of each cycle, the N-Channel MOSFET switch is turned on, forcing the inductor current to rise. The current at the source of the switch is internally measured and converted to a voltage by the current sense amplifier. That voltage is compared to the error voltage. When the inductor current rises sufficiently, the PWM comparator turns off the switch, forcing the inductor current to the output capacitor through the internal P-Channel MOSFET rectifier, which forces the inductor current to decrease. The peak inductor current is controlled by the error voltage, which in turn is controlled by the output voltage. Thus the output voltage controls the inductor current to satisfy the load.
Soft-Start
The MP1543 includes a soft-start timer that limits the voltage at the error amplifier output during startup to prevent excessive current at the input. This prevents premature termination of the source voltage at startup due to inrush current. This also limits the inductor current at startup, forcing the input current to rise slowly to the amount required to regulate the output voltage during soft-start.
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
5
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
APPLICATION INFORMATION
COMPONENT SELECTION
Setting the Output Voltage Set the output voltage by selecting the resistive voltage divider ratio. The voltage divider drops the output voltage to the 1.2V feedback voltage. Use a 100k resistor for R2 of the voltage divider. Determine the high-side resistor R1 by the equation:
R1 = VOUT - VFB VFB R2
Selecting the Inductor The inductor is required to force the output voltage higher while being driven by the lower input voltage. A good rule for determining the inductance is to allow the peak-to-peak ripple current to be approximately 30%-50% of the maximum input current. Make sure that the peak inductor current is below the minimum current limit at the duty cycle used (to prevent loss of regulation due to the current limit variations). Calculate the required inductance value L using the equations:
L= VIN x (VOUT - VIN ) VOUT x f SW x I
Where VOUT is the output voltage, VFB is the 1.2V feedback voltage and R2=100k. Selecting the Input Capacitor An input capacitor is required to supply the AC ripple current to the inductor, while limiting noise at the input source. Multi-layer ceramic capacitors are the best choice as they have extremely low ESR and are available in small footprints. Use an input capacitor value of 4.7F or greater. This capacitor must be placed physically close to the device. Selecting the Output Capacitor A single 4.7F to 10F ceramic capacitor usually provides sufficient output capacitance for most applications. Larger values up to 22F may be used to obtain extremely low output voltage ripple and improve transient response. The impedance of the ceramic capacitor at the switching frequency is dominated by the capacitance, and so the output voltage ripple is mostly independent of the ESR. The output voltage ripple VRIPPLE is calculated as:
VRIPPLE = ILOAD (VO UT - VIN ) VO UT x C2 x f SW
IIN(MAX ) =
VOUT x ILOAD (MAX ) VIN x
I = (30% - 50%)IIN(MAX)
Where ILOAD(MAX) is the maximum load current, I is the peak-to-peak inductor ripple current and is efficiency. For the MP1543, typically, 4.7H is recommended for most applications. Choose an inductor that does not saturate at the peak switch current as calculated above with additional margin to cover heavy load transients and extreme startup conditions.
Where VIN is the input voltage, ILOAD is the load current, C2 is the capacitance of the output capacitor and fSW is the 500KHz switching frequency.
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
6
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER Selecting the Feed-Forward Capacitor A feed-forward capacitor C3 in parallel with the high-side resistor R1 can be added to improve the output ripple at discontinuous conduction mode and the load transient response (see Figure 2). Up to 220pF for this capacitor is recommended for 3.3V output applications. Selecting the Schottky Diode A Schottky diode D1 in parallel with the highside P-Channel MOSFET is necessary to clamp the SW node to a safe level for outputs of 4V or above. A 0.5A, 20V Schottky diode can be used for this purpose. See Figure 3.
LAYOUT CONSIDERATIONS
High frequency switching regulators require very careful layout for stable operation and low noise. All components must be placed as close to the IC as possible. All feedback components must be kept close to the FB pin to prevent noise injection on the FB pin trace. The ground return of C1 and C2 should be tied close to the GND pin. See the MP1543 demo board layout for reference.
VIN 1.8V - 3.2V
4 SW OUT 5 3
EN
EN
MP1543
FB 1
C3 Up to 220pF OPTIONAL
VOUT 3.3V 400mA
GND 2
MP1543_F02
Figure 2--3.3V Typical Application Circuit with Feed-Forward Capacitor
D1 VIN
2.5V - 4.2V 4 SW OUT 5 3
EN
EN
MP1543
FB 1
VOUT 5V 400mA
GND 2
MP1543_F02
Figure 3--5V Typical Application Circuit with External Schottky Diode and Output Disconnect Not Required
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
7
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
D1 VIN
2.5V - 4.2V 4 SW OUT 5 3
P1 VOUT 5V 400mA
EN
EN
MP1543
FB 1
GND 2
MP1543_F03
Figure 4--5V Typical Application Circuit with External Schottky Diode and Output Disconnect Required
MP1543 Rev. 1.0 1/11/2006
www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
8
TM
MP1543 -- 1.5A, 500KHZ SYNCHRONOUS RECTIFIED STEP-UP CONVERTER
PACKAGE INFORMATION
TSOT23-5
2.90 BSC
3
0.950 TYP.
0.950 TYP.
10TYP. (2 plcs)
3
C L
1.60 BSC
2.80 BSC
0
0.25 BSC.
+ 4 - 0
0.400
0.10
0.300(Min) 0.500(Max) (5 PLCS)
Gauge Plane
C L
1.00 Max.
0.870.03
SEATING PLANE
0.00-0.10
10 TYP. (2 plcs)
0.127 TYP.
Dimensions are in millimeters
NOTE: 1. Dimensions and tolerances are as per ANSI Y14.5M, 1994. 2. Die is facing up for mold. Die is facing down for trim/form, ie. reverse trim/form. 3. Dimensions are exclusive of mold flash and gate burr. 4. The footlength measuring is based on the gauge plane method. 5. All specification comply to Jedec Spec MO193 Issue C.
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications. 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.
MP1543 Rev. 1.0 1/11/2006 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. (c) 2006 MPS. All Rights Reserved.
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