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0.00 0.09 0.18 0.27 0.36 0.45 0.54

EFFICIENCY (%)

OUT

(A)

Vin = 3.0V

Vin = 3.2V

Vin = 3.4V

Vin = 3.6V

Vin = 3.8V

Vin = 4.0V

0.00 0.04 0.08 0.12 0.16 0.20

EFFICIENCY (%)

OUT

(A)

Vin = 2.0V

Vin = 2.2V

Vin = 2.5V

Vin = 2.80

LMR61428

www.ti.com

SNVS815A –JUNE 2012–REVISED APRIL 2013

LMR61428 SIMPLE SWITCHER

14Vout, 2.85A Step-Up Voltage Regulator in VSSOP

Check for Samples: LMR61428

FEATURES

DESCRIPTION

The LMR61428 is a step-up DC-DC switching

• 1.2V to 14V Input Voltage

regulator for battery-powered and low input voltage

• Adjustable Output Voltage up to 14V

systems that can achieve efficiencies up to 90%. It

• Switch Current up to 2.85A

has a wide input voltage range from 1.2V to 14V and

a possible regulated output voltage range of 1.24V to

• Up to 2 MHz Switching Frequency

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

• Low Shutdown Iq, <1µA

power switch.

• Cycle-by-Cycle Current Limiting

The high switching frequency of up to 2MHz of the

• VSSOP Packaging (3.0 x 5.0 x 1.09mm)

LMR61428 allows for tiny surface mount inductors

• WEBENCH

Enabled

and capacitors. Because of the unique constant-duty-

cycle gated oscillator topology very high efficiencies

are realized over a wide load range. The supply

PERFORMANCE BENEFITS

current is reduced to 80µA because of the BiCMOS

• Extremely Easy to Use

process technology. In the shutdown mode, the

• Tiny Overall Solution Reduces System Cost

supply current is less than 2.5µA. The LMR61428 is

available in a VSSOP-8 package.

APPLICATIONS

• Boost/SEPIC Conversions from 3.3V, 5V, and

12V

• Space Constrained Applications

• LCD Displays

• LED Applications

System Performance

Efficiency vs Load Current, V

OUT

= 5V Efficiency vs Load Current, V

OUT

= 3.3V

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.

2SIMPLE SWITCHER, WEBENCH are registered trademarks of Texas Instruments.

3All other 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 (19 pages)

PAGE 1
LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 LMR61428 SIMPLE SWITCHER® 14Vout, 2.85A Step-Up Voltage Regulator in VSSOP Check for Samples: LMR61428 FEATURES DESCRIPTION • • • • • • • • The LMR61428 is a step-up DC-DC switching regulator for battery-powered and low input voltage systems that can achieve efficiencies up to 90%. It has a wide input voltage range from 1.2V to 14V and a possible regulated output voltage range of 1.24V to 14V. It has an internal 0.
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LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com Typical Application Circuit Connection Diagram VSSOP Package (Top View) See Package Number DGK PIN DESCRIPTION Pin 2 Name Function 1 PGND Power Ground 2 EN Active-Low Shutdown Input 3 FREQ Frequency Adjust. An external resistor connected between this pin and Pin 6 (VDD) sets the switching frequency of the LMR61428.
PAGE 3
LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 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 −0.5V to 10V BOOT, VDD, EN and FB Pins FREQ Pin θJA 100µA (3) 240°C/W TJmax (3) 150°C −65°C to +150°C Storage Temperature Range Lead Temp.
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LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com 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. Typ Max Units VIN_ST Symbol Minimum Start-Up Supply Voltage ILOAD = 0mA Parameter Condition Min 1.1 1.2 V VIN_OP Minimum Operating Supply Voltage (once started) 0.
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LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS All curves taken at TA = 25°C, unless specified otherwise. Efficiency vs Load Current VOUT = 3.3V 84 80 82 77 80 74 78 EFFICIENCY (%) EFFICIENCY (%) Efficiency vs Load Current VOUT = 5.0V 76 74 72 Vin = 3.0V Vin = 3.2V Vin = 3.4V Vin = 3.6V Vin = 3.8V Vin = 4.0V 70 68 66 64 0.00 0.09 0.18 0.27 0.36 IOUT(A) 71 68 65 62 59 Vin = 2.0V Vin = 2.2V Vin = 2.5V Vin = 2.80 56 53 0.45 0.54 50 0.
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LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com IOP vs VDD VIN_ST vs Load Current VOUT = 3.3V Figure 7. Figure 8. Switching Frequency vs RFQ Peak Inductor Current vs Load Current Figure 9. Figure 10. Minimum Input Voltage vs Load Current Steady State Operation VSW 5V/Div VOUT = 5V 50 mV/Div 10 Ps/DIV Figure 11. 6 Figure 12.
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LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 Simplified Block Diagram Figure 13.
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LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com DETAILED DESCRIPTION OPERATING PRINCIPLE The LMR61428 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. The switching DC-DC regulator boosts an input voltage between 1.2V and 14V to a regulated output voltage between 1.
PAGE 9
LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 LOW VOLTAGE START-UP The LMR61428 can start-up from input voltages as low as 1.1V. On start-up, the control circuitry switches the Nchannel MOSFET continuously at 70% duty cycle until the output voltage reaches 2.5V. After this output voltage is reached, the normal step-up regulator feedback and gated oscillator control scheme take over. Once the device is in regulation it can operate down to a 0.
PAGE 10
LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com BOOTSTRAPPING When the output voltage (VOUT) is between 2.5V and 5.0V a bootstrapped operation is suggested. This is achieved by connecting the VDD pin (Pin 6) to VOUT. However if the VOUT is outside this range, the VDD pin should be connected to a voltage source whose range is between 2.5V and 5V. This can be the input voltage (VIN), VOUT stepped down using a linear regulator, or a different voltage source available in the system.
PAGE 11
LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 OUTPUT DIODE SELECTION A Schottky diode should be used for the output diode. The forward current rating of the diode should be higher than the load current, and the reverse voltage rating must be higher than the output voltage. Do not use ordinary rectifier diodes, since slow switching speeds and long recovery times cause the efficiency and the load regulation to suffer.
PAGE 12
LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com Application Examples Figure 17. EXAMPLE 1. 5V/0.
PAGE 13
LMR61428 www.ti.com SNVS815A – JUNE 2012 – REVISED APRIL 2013 Figure 18. EXAMPLE 2. 2mm Tall 5V/0.
PAGE 14
LMR61428 SNVS815A – JUNE 2012 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Original (April 2013) to Revision A • 14 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-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 LMR61428XMM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LMR61428XMMX/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.
PAGE 17
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMR61428XMM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0 LMR61428XMMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.
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