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MP2307

3A, 23V, 340KHz Synchronous Rectified

Step-Down Converter

MP2307 Rev. 1.9 www.MonolithicPower.com 1

5/28/2008 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

The Future of Analog IC Technology

DESCRIPTION

The MP2307 is a monolithic synchronous buck

regulator. The device integrates 100m

MOSFETS that provide 3A of continuous load

current over a wide operating input voltage of

4.75V to 23V. Current mode control provides

fast transient response and cycle-by-cycle

current limit.

An adjustable soft-start prevents inrush current

at turn-on and in shutdown mode, the supply

current drops below 1µA.

This device, available in an 8-pin SOIC

package, provides a very compact system

solution with minimal reliance on external

components.

EVALUATION BOARD REFERENCE

Board Number Dimensions

EV2307DN-00A 2.0”X x 1.5”Y x 0.5”Z

FEATURES

• 3A Continuous Output Current

4A Peak Output Current

• Wide 4.75V to 23V Operating Input Range

• Integrated 100m Power MOSFET Switches

• Output Adjustable from 0.925V to 20V

• Up to 95% Efficiency

• Programmable Soft-Start

• Stable with Low ESR Ceramic Output Capacitors

• Fixed 340KHz Frequency

• Cycle-by-Cycle Over Current Protection

• Input Under Voltage Lockout

• Thermally Enhanced 8-Pin SOIC Package

APPLICATIONS

• Distributed Power Systems

• Networking Systems

• FPGA, DSP, ASIC Power Supplies

• Green Electronics/Appliances

• Notebook Computers

“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of

Monolithic Power Systems, Inc.

TYPICAL APPLICATION

INPUT

4.75V to 23V

OUTPUT

3.3V

3.9nF

10nF

MP2307

BSIN

GND COMP

MP2307_TAC01

100

EFFICIENCY (%)

0.1 1.0 10

LOAD CURRENT (A)

MP2307_EC01

Efficiency vs

Load Current

= 5V

= 23V

= 12V

Summary of content (12 pages)

PAGE 1
MP2307 3A, 23V, 340KHz Synchronous Rectified Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2307 is a monolithic synchronous buck regulator. The device integrates 100mΩ MOSFETS that provide 3A of continuous load current over a wide operating input voltage of 4.75V to 23V. Current mode control provides fast transient response and cycle-by-cycle current limit.
PAGE 2
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER ABSOLUTE MAXIMUM RATINGS (1) PACKAGE REFERENCE Supply Voltage VIN ....................... –0.3V to +26V Switch Voltage VSW ................. –1V to VIN + 0.3V Boost Voltage VBS ..........VSW – 0.3V to VSW + 6V All Other Pins................................. –0.3V to +6V Junction Temperature...............................150°C Lead Temperature ....................................260°C Storage Temperature .............
PAGE 3
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (continued) VIN = 12V, TA = +25°C, unless otherwise noted. Parameter Symbol Condition EN Lockout Threshold Voltage EN Lockout Hysterisis Input Under Voltage Lockout Threshold Input Under Voltage Lockout Threshold Hysteresis Soft-Start Current Soft-Start Period Thermal Shutdown (5) VIN Rising VSS = 0V CSS = 0.1µF Min Typ Max Units 2.2 2.5 210 2.7 V mV 3.80 4.05 4.
PAGE 4
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS C1 = 2 x 10µF, C2 = 2 x 22µF, L= 10µH, CSS= 0.1µF, TA = +25°C, unless otherwise noted. Steady State Test Waveforms Steady State Test Waveforms Startup through Enable Waveforms VIN = 12V, VOUT = 3.3V, IOUT = 0A VIN = 12V, VOUT = 3.3V, IOUT = 3A VIN = 12V, VOUT = 3.3V, No Load VIN 20mV/div. VIN 200mV/div. VOUT 20mV/div. VOUT 20MV/div. VSW 10V/div. VSW V/div. IL 1A/div. VEN 5V/div. VOUT 2V/div.
PAGE 5
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER PIN FUNCTIONS Pin # Name 1 BS 2 IN 3 SW 4 GND 5 FB 6 COMP 7 EN 8 SS MP2307 Rev. 1.9 5/28/2008 Description High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET switch. Connect a 0.01µF or greater capacitor from SW to BS to power the high side switch. Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.75V to 23V power source.
PAGE 6
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER OPERATION FUNCTIONAL DESCRIPTION The MP2307 regulates input voltages from 4.75V to 23V down to an output voltage as low as 0.925V, and supplies up to 3A of load current. The MP2307 uses current-mode control to regulate the output voltage. The output voltage is measured at FB through a resistive voltage divider and amplified through the internal transconductance error amplifier.
PAGE 7
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER APPLICATIONS INFORMATION The inductance value can be calculated by: COMPONENT SELECTION Setting the Output Voltage The output voltage is set using a resistive voltage divider connected from the output voltage to FB.
PAGE 8
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER Since the input capacitor (C1) absorbs the input switching current, it requires an adequate ripple current rating. The RMS current in the input capacitor can be estimated by: I C1 = ILOAD × VOUT ⎛⎜ VOUT ⎞⎟ × 1− VIN ⎜⎝ VIN ⎟⎠ When using tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency.
PAGE 9
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER The system has one zero of importance, due to the compensation capacitor (C3) and the compensation resistor (R3). This zero is located at: f Z1 = 1 2π × C3 × R3 The system may have another zero of importance, if the output capacitor has a large capacitance and/or a high ESR value.
PAGE 10
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER 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. External Bootstrap Diode An external bootstrap diode may enhance the efficiency of the regulator, the applicable conditions of external BS diode are: z VOUT is 5V or 3.
PAGE 11
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER TYPICAL APPLICATION CIRCUIT C5 10nF INPUT 4.75V to 23V 2 7 8 1 IN BS SW EN MP2307 SS GND FB COMP 4 5 6 C6 (optional) OUTPUT 3.3V 3A 3 C3 3.9nF D1 B130 (optional) MP2307_F03 Figure 4—MP2307 with 3.3V Output, 22uF/6.3V Ceramic Output Capacitor MP2307 Rev. 1.9 5/28/2008 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 MPS. All Rights Reserved.
PAGE 12
MP2307 – 3A, 23V, 340KHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER PACKAGE INFORMATION SOIC8N (EXPOSED PAD) 0.189(4.80) 0.197(5.00) 8 0.124(3.15) 0.136(3.45) 5 0.150(3.80) 0.157(4.00) PIN 1 ID 1 0.228(5.80) 0.244(6.20) 0.089(2.26) 0.101(2.56) 4 TOP VIEW BOTTOM VIEW SEE DETAIL "A" 0.013(0.33) 0.020(0.51) 0.051(1.30) 0.067(1.70) SEATING PLANE 0.000(0.00) 0.006(0.15) 0.0075(0.19) 0.0098(0.25) SIDE VIEW 0.050(1.27) BSC FRONT VIEW 0.010(0.25) x 45o 0.020(0.50) GAUGE PLANE 0.010(0.25) BSC 0.