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LM2621

www.ti.com

SNVS033C –MAY 2004–REVISED MARCH 2005

LM2621 Low Input Voltage, Step-Up DC-DC Converter

Check for Samples: LM2621

FEATURES

DESCRIPTION

The LM2621 is a high efficiency, step-up DC-DC

• Small VSSOP8 Package (Half the Footprint of

switching regulator for battery-powered and low input

Standard 8-Pin SOIC Package)

voltage systems. It accepts an input voltage between

• 1.09 mm Package Height

1.2V and 14V and converts it into a regulated output

• Up to 2 MHz Switching Frequency

voltage. The output voltage can be adjusted between

1.24V and 14V. It has an internal 0.17Ω N-Channel

• 1.2V to 14V Input Voltage

MOSFET power switch. Efficiencies up to 90% are

• 1.24V - 14V Adjustable Output Voltage

achievable using the LM2621.

• Up to 1A Load Current

The high switching frequency (adjustable up to 2MHz)

• 0.17 Ω Internal MOSFET

of the LM2621 allows for tiny surface mount inductors

• Up to 90% Regulator Efficiency

and capacitors. Because of the unique constant-duty-

cycle gated oscillator topology very high efficiencies

• 80 µA Typical Operating Current

are realized over a wide load range. The supply

• <2.5µA Ensured Supply Current In Shutdown

current is reduced to 80µA because of the BiCMOS

process technology. In the shutdown mode, the

APPLICATIONS

supply current is less than 2.5µA.

• PDAs, Cellular Phones

The LM2621 is available in a VSSOP-8 package.

• 2-Cell and 3-Cell Battery-Operated Equipment This package uses half the board area of a standard

8-pin SOIC and has a height of just 1.09 mm.

• PCMCIA Cards, Memory Cards

• Flash Memory Programming

• TFT/LCD Applications

• 3.3V to 5.0V Conversion

• GPS Devices

• Two-Way Pagers

• Palmtop Computers

• Hand-Held Instruments

Typical Application Circuit

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (17 pages)

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LM2621 www.ti.com SNVS033C – MAY 2004 – REVISED MARCH 2005 LM2621 Low Input Voltage, Step-Up DC-DC Converter Check for Samples: LM2621 FEATURES DESCRIPTION • The LM2621 is a high efficiency, step-up DC-DC switching regulator for battery-powered and low input voltage systems. It accepts an input voltage between 1.2V and 14V and converts it into a regulated output voltage. The output voltage can be adjusted between 1.24V and 14V. It has an internal 0.17Ω N-Channel MOSFET power switch.
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LM2621 SNVS033C – MAY 2004 – REVISED MARCH 2005 www.ti.com Connection Diagram Figure 1. VSSOP-8 (DGK) Package - Top View These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. ABSOLUTE MAXIMUM RATINGS (1) (2) −0.5 V to 14.5V SW Pin Voltage −0.
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LM2621 www.ti.com SNVS033C – MAY 2004 – REVISED MARCH 2005 ELECTRICAL CHARACTERISTICS Limits in standard typeface are for TJ = 25°C, and limits in boldface type apply over the full operating temperature range of −40°C to +85°C. Unless otherwise specified: VDD= VOUT= 3.3V. Condition Typ VIN_ST Symbol Minimum Start-Up Supply Voltage (1) Parameter ILOAD = 0mA 1.1 VIN_OP Minimum Operating Supply Voltage (once started) ILOAD = 0mA 0.65 VFB FB Pin Voltage VOUT_M Maximum Output Voltage 1.
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LM2621 SNVS033C – MAY 2004 – REVISED MARCH 2005 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Load Current VOUT = 5.0V Efficiency vs Load Current VOUT = 3.3V Figure 2. Figure 3. VFB vs Temperature 4 IOP vs Temperature Figure 4. Figure 5. ISD vs Temperature ISD vs VDD Figure 6. Figure 7.
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LM2621 www.ti.com SNVS033C – MAY 2004 – REVISED MARCH 2005 TYPICAL PERFORMANCE CHARACTERISTICS (continued) IOP vs VDD VIN_ST vs Load Current VOUT = 3.3V Figure 8. Figure 9. Switching Frequency vs RFQ Peak Inductor Current vs Load Current Figure 10. Figure 11. Maximum Load Current vs Input Voltage Figure 12.
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LM2621 SNVS033C – MAY 2004 – REVISED MARCH 2005 www.ti.com DETAILED DESCRIPTION OPERATING PRINCIPLE The LM2621 is designed to provide step-up DC-DC voltage regulation in battery-powered and low-input voltage systems. It combines a step-up switching regulator, N-channel power MOSFET, built-in current limit, thermal limit, and voltage reference in a single 8-pin VSSOP package Figure 13. The switching DC-DC regulator boosts an input voltage between 1.2V and 14V to a regulated output voltage between 1.
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LM2621 www.ti.com SNVS033C – MAY 2004 – REVISED MARCH 2005 Because of this type of control scheme, the quiescent current is inherently very low. At light loads the gated oscillator control scheme offers a much higher efficiency compared to the conventional PWM control scheme. Figure 14. Typical Step-Up Regulator Waveforms LOW VOLTAGE START-UP The LM2621 can start-up from input voltages as low as 1.1V.
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LM2621 SNVS033C – MAY 2004 – REVISED MARCH 2005 www.ti.com Design Procedure SETTING THE OUTPUT VOLTAGE The output voltage of the step-up regulator can be set between 1.24V and 14V by connecting a feedback resistive divider made of RF1 and RF2. The resistor values are selected as follows: RF2 = RF1 /[(VOUT/ 1.24) −1] (1) A value of 150kΩ is suggested for RF1. Then, RF2 can be selected using the above equation.
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LM2621 www.ti.com SNVS033C – MAY 2004 – REVISED MARCH 2005 Table 1.
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LM2621 SNVS033C – MAY 2004 – REVISED MARCH 2005 www.ti.com Application examples Figure 15. EXAMPLE 1 – 5V/0.5A Step-Up Regulator U1 Texas Instruments LM2621MM C1 Vishay/Sprague 595D226X06R3B2T, Tantalum C2 Vishay/Sprague 595D686X0010C2T, Tantalum D1 Motorola MBRS140T3 L Coilcraft DT1608C-682 Figure 16. EXAMPLE 2 – 2mm Tall 5V/0.
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LM2621 www.ti.com SNVS033C – MAY 2004 – REVISED MARCH 2005 Figure 17. EXAMPLE 3 – 3.3V/0.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
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PACKAGE MATERIALS INFORMATION www.ti.com 21-Mar-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2621MM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM2621MMX VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM2621MMX/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 21-Mar-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2621MM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LM2621MMX VSSOP DGK 8 3500 367.0 367.0 35.0 LM2621MMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.
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