LM2734YMK Electronic IC Chips Thin SOT23 1A Load Step-Down DC-DC Regulator

LM2734 Thin SOT23 1A Load Step-Down DC-DC Regulator

General Description

The LM2734 regulator is a monolithic, high frequency, PWM step-down DC/DC converter in a 6-pin Thin SOT23 package. It provides all the active functions to provide local DC/DC conversion with fast transient response and accurate regulation in the smallest possible PCB area.

With a minimum of external components and online design support through WEBENCH™, the LM2734 is easy to use. The ability to drive 1A loads with an internal 300mΩ NMOS switch using state-of-the-art 0.5µm BiCMOS technology results in the best power density available. The world class control circuitry allows for on-times as low as 13ns, thus supporting exceptionally high frequency conversion over the entire 3V to 20V input operating range down to the minimum output voltage of 0.8V. Switching frequency is internally set to 550kHz (LM2734Y) or 1.6MHz (LM2734X), allowing the use of extremely small surface mount inductors and chip capacitors.

Even though the operating frequencies are very high, efficiencies up to 90% are easy to achieve. External shutdown is included, featuring an ultra-low stand-by current of 30nA. The LM2734 utilizes current-mode control and internal compensation to provide high-performance regulation over a wide range of operating conditions. Additional features include internal soft-start circuitry to reduce inrush current, pulse-by-pulse current limit, thermal shutdown, and output over-voltage protection.

Features

• Thin SOT23-6 package

• 3.0V to 20V input voltage range

• 0.8V to 18V output voltage range

• 1A output current

• 550kHz (LM2734Y) and 1.6MHz (LM2734X) switching frequencies

• 300mΩ NMOS switch

• 30nA shutdown current

• 0.8V, 2% internal voltage reference

• Internal soft-start

• Current-Mode, PWM operation

• WEBENCH online design tool

Applications

• Local Point of Load Regulation

• Core Power in HDDs

• Set-Top Boxes

• Battery Powered Devices

• USB Powered Devices

• DSL Modems

• Notebook Computers

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

V_IN                                                                              -0.5V to 24V

SW Voltage                                                                 -0.5V to 24V

Boost Voltage                                                             -0.5V to 30V

Boost to SW Voltage                                                 -0.5V to 6.0V

FB Voltage                                                                -0.5V to 3.0V

EN Voltage                                                     -0.5V to (V_IN + 0.3V)

Junction Temperature                                                         150˚C

ESD Susceptibility (Note 2)                                                     2kV

Storage Temp. Range                                           -65˚C to 150˚C

Soldering Information

    Infrared/Convection Reflow (15sec)                                 220˚C

    Wave Soldering Lead Temp. (10sec)                               260˚C

Operating Ratings (Note 1)

V_IN                                                                                                              3V to 20V

SW Voltage                                                                 -0.5V to 20V

Boost Voltage                                                              -0.5V to 25V

Boost to SW Voltage                                                    1.6V to 5.5V

Junction Temperature Range                                −40˚C to +125˚C

Thermal Resistance θ_JA (Note 3)                                      118˚C/W

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see Electrical Characteristics.

Note 2: Human body model, 1.5kΩ in series with 100pF.

Note 3: Thermal shutdown will occur if the junction temperature exceeds 165˚C. The maximum power dissipation is a function of TJ(MAX) , θJA and TA . The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) – TA)/θJA . All numbers apply for packages soldered directly onto a 3” x 3” PC board with 2oz. copper on 4 layers in still air. For a 2 layer board using 1 oz. copper in still air, θJA = 204˚C/W.

Typical Application Circuit

Connection Diagram

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