Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Holder HTSSOP 16

PVIN

AVIN

AGND

PGND

LM2854

OUT

FB1

COMP

FB2

LM2854

www.ti.com

SNVS560C –MARCH 2008–REVISED APRIL 2013

LM2854 4A 500 kHz / 1 MHz Synchronous SIMPLE SWITCHER

Buck Regulator

Check for Samples: LM2854

FEATURES

DESCRIPTION

The LM2854 PowerWise™ SIMPLE SWITCHER

234

• Input Voltage Range of 2.95V to 5.5V

buck regulator is a 500 kHz or 1 MHz step-down

• Maximum Load Current of 4A

switching voltage regulator capable of driving up to a

• Wide Bandwidth Voltage Mode Control Loop,

4A load with exceptional power conversion efficiency,

Partial Internal Compensation

line and load regulation, and output accuracy. The

LM2854 can accept an input voltage rail between

• Fixed Switching Frequency of 500 kHz or 1

2.95V and 5.5V and deliver an adjustable and highly

MHz

accurate output voltage as low as 0.8V. Externally

• 35 mΩ Integrated MOSFET Switches

established soft-start with a small capacitor facilitates

• Adjustable Output Voltage Down to 0.8V

controlled start-up, and the LM2854 is capable of

starting gracefully into a pre-biased output voltage.

• Optimized Reference Voltage Initial Accuracy

Partial internal compensation reduces the number of

and Temperature Drift

external passive components and PC board space

• External Soft-Start Control with Tracking

typically necessary in a voltage mode buck converter

Capability

application, yet preserving flexibility to deal with

ceramic and/or electrolytic based load capacitors.

• Enable Pin with Hysteresis

Lossless cycle-by-cycle peak current limit is used to

• Low Standby Current of 230 µA

protect the load from an overcurrent or short-circuit

• Pre-Biased Load Startup Capability

fault, and an enable comparator simplifies

sequencing applications. The LM2854 is available in

• Integrated UVLO, OCP and Thermal Shutdown

an exposed pad HTSSOP-16 package that enhances

• 100% Duty Cycle Capability

the thermal performance of the regulator.

• HTSSOP-16 Exposed Pad Package

Typical Application Circuit

APPLICATIONS

• Low Voltage POL Regulation from 5V or 3.3V

Rail

• Local Solution for FPGA/DSP/ASIC/µP Core or

I/O Power

• Broadband Networking and Communications

Infrastructure

• Portable Computing

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 is a registered trademark of Texas Instruments, Inc.

3PowerWise is a trademark of Texas Instrumetns, Inc.

4All 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 (30 pages)

PAGE 1
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 LM2854 4A 500 kHz / 1 MHz Synchronous SIMPLE SWITCHER® Buck Regulator Check for Samples: LM2854 FEATURES DESCRIPTION • Input Voltage Range of 2.95V to 5.5V • Maximum Load Current of 4A • Wide Bandwidth Voltage Mode Control Loop, Partial Internal Compensation • Fixed Switching Frequency of 500 kHz or 1 MHz • 35 mΩ Integrated MOSFET Switches • Adjustable Output Voltage Down to 0.
PAGE 2
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Connection Diagram NC 1 16 FB PGND 2 15 AGND PGND 3 14 SS PGND 4 PVIN 5 13 SW EXP 12 SW PVIN 6 11 EN PVIN 7 10 AVIN NC 8 9 NC Figure 1. 16-Lead HTSSOP – Top View See Package Number PWP PIN DESCRIPTIONS Pin Number Name 1 NC Description 2,3,4 PGND Power ground pins for the internal power switches. These pins should be connected together locally at the device and tied to the PC board ground plane.
PAGE 3
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) (3) PVIN, AVIN, SW, EN, FB, SS to GND -0.3V to 6.0V ESD Susceptibility (4) ±2 kV Power Dissipation Internally Limited Junction Temperature 150°C −65°C to +150°C Storage Temperature Range Lead Temperature Soldering (10 sec) 260°C Vapor Phase (60 sec) 215°C Infrared (1) (2) (3) (4) 220°C Absolute Maximum Ratings are limits beyond which damage to the device may occur.
PAGE 4
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Electrical Characteristics Specifications with standard typeface are for TJ = 25°C only; limits in bold face type apply over the Operating Junction Temperature Range TJ range of -40°C to 125°C. Minimum and maximum limits are ensured through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. AVIN = PVIN = EN = 5.
PAGE 5
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 Typical Performance Characteristics Unless otherwise specified, the following conditions apply: VIN = PVIN = AVIN = EN = 5.0V, CIN is 47 µF 10V X5R ceramic capacitor, LO is from TDK SPM6530T family; TAMBIENT = 25°C for efficiency curves, bode plots and waveforms, and TJ = 25°C for all others. Feedback Voltage vs. Temperature UVLO Threshold vs. Temperature 2.65 0.802 UVLO THRESHOLD (V) FB VOLTAGE (V) 0.801 0.800 0.799 0.798 0.797 2.60 2.
PAGE 6
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = PVIN = AVIN = EN = 5.0V, CIN is 47 µF 10V X5R ceramic capacitor, LO is from TDK SPM6530T family; TAMBIENT = 25°C for efficiency curves, bode plots and waveforms, and TJ = 25°C for all others. NMOS RDS(ON) vs. Temperature IQ (operating) vs. VIN and Temperature 50 1.8 1.7 IQ OPERATING (mA) NMOS RDSON (m:) 45 40 VIN = 3.
PAGE 7
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = PVIN = AVIN = EN = 5.0V, CIN is 47 µF 10V X5R ceramic capacitor, LO is from TDK SPM6530T family; TAMBIENT = 25°C for efficiency curves, bode plots and waveforms, and TJ = 25°C for all others. LM2854 1 MHz Efficiency vs. IOUT VOUT = 0.8V, LO = 0.47 µH, 3.3 mΩ DCR LM2854 1 MHz Efficiency vs. IOUT VOUT = 2.5V, LO = 1.0 µH, 7.
PAGE 8
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = PVIN = AVIN = EN = 5.0V, CIN is 47 µF 10V X5R ceramic capacitor, LO is from TDK SPM6530T family; TAMBIENT = 25°C for efficiency curves, bode plots and waveforms, and TJ = 25°C for all others. LM2854 500 kHz Efficiency vs. IOUT VOUT = 2.5V, LO = 2.2 µH, 16 mΩ DCR 99 96 98 94 97 92 VIN = 3.
PAGE 9
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = PVIN = AVIN = EN = 5.0V, CIN is 47 µF 10V X5R ceramic capacitor, LO is from TDK SPM6530T family; TAMBIENT = 25°C for efficiency curves, bode plots and waveforms, and TJ = 25°C for all others. LM2854 1 MHz Bode Plot VIN = 5.0V, VOUT = 1.8V, IOUT = 4A RFB1 = 150 kΩ, RCOMP = 1 kΩ, CCOMP = 100 pF, LOUT = 0.
PAGE 10
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = PVIN = AVIN = EN = 5.0V, CIN is 47 µF 10V X5R ceramic capacitor, LO is from TDK SPM6530T family; TAMBIENT = 25°C for efficiency curves, bode plots and waveforms, and TJ = 25°C for all others. LM2854 500 kHz Power Off Characteristic VIN = 5.0V, VOUT = 1.8V, IOUT = 4A, CSS = 220 pF LM2854 1 MHz Load Transient Response VIN = 5.
PAGE 11
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 BLOCK DIAGRAM AGND PVIN 0.8V Reference Current Limit UVLO AVIN EN + - Gate Drive Error Amplifier 1.
PAGE 12
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com APPLICATIONS INFORMATION GENERAL The LM2854 PowerWise synchronous DC-DC buck regulator belongs to the Texas Instruments SIMPLE SWITCHER family of switching regulators. Integration of the power MOSFETs and associated drivers, compensation component network and the PWM controller reduces the number of external components necessary for a complete power supply design, without sacrificing performance.
PAGE 13
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 PRE-BIASED STARTUP CAPABILITY The LM2854 is in a pre-biased state when the device starts up with an output voltage greater than zero. This often occurs in many multi-rail applications such as when powering an FPGA, ASIC, or DSP. The output can be pre-biased in these applications through parasitic conduction paths from one supply rail to another.
PAGE 14
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Design Guidelines INPUT FILTER CAPACITOR Fast switching currents place a large strain on the input supply to a buck regulator. A capacitor placed close to the PVIN and PGND pins of the LM2854 helps to supply the instantaneous charge required when the regulator demands a pulse of current every switching cycle. In fact, the input capacitor conducts a square-wave current of peak-to-peak amplitude equal to IOUT.
PAGE 15
LM2854 www.ti.com CSS = SNVS560C – MARCH 2008 – REVISED APRIL 2013 tSS x 2 PA 0.8V (5) Thus, the required soft start capacitor per unit output voltage startup time is given by CSS = 2.5 nF / ms (6) For example, a 10 nF soft-start capacitor will yield a 4 ms soft-start time.
PAGE 16
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com SIMULTANEOUS STARTUP VOUT1 VOLTAGE VOUT2 EN TIME ENABLE AND UVLO Using a resistor divider from VIN to EN as shown in the schematic diagram below, the input voltage at which the part begins switching can be increased above the normal input UVLO level according to REN1 + REN2 VIN(UVLO) = 1.23V REN2 (10) For example, suppose that the required input UVLO level is 3.69V. Choosing REN2 = 10 kΩ, then we calculate REN1 = 20 kΩ.
PAGE 17
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 COMPENSATION COMPONENT SELECTION The power stage transfer function of a voltage mode buck converter has a complex double pole related to the LC output filter and a left half plane zero due to the output capacitor ESR, denoted RESR.
PAGE 18
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 RFB1 = www.ti.com 1 2SCCOMPfLC RCOMP = 1 2SCCOMPfESR (15) Note that the lower feedback resistor, RFB2, has no impact on the control loop from an AC standpoint since the FB pin is the input to an error amplifier and effectively at AC ground. Hence, the control loop can be designed irrespective of output voltage level. The only caveat here is the necessary derating of the output capacitance with applied voltage.
PAGE 19
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 Table 4 lists some examples of commercially available capacitors that can be used with the LM2854. Table 1. LM2854 500 kHz Compensation Component Values VIN (V) LO (µH) 5.0 3.3 CO (µF) ESR (mΩ) RFB1 (kΩ) CCOMP (pF) RCOMP (kΩ) 10 150 47 1 1 5 150 100 1 15 25 150 120 25 2 10 150 68 1 1 5 150 120 1 220 15 25 120 120 15 100 2 10 150 68 1 100 200 1 5 100 150 1 1.5 100 220 15 25 100 150 15 2.
PAGE 20
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com Table 3. Recommended Filter Inductors (continued) Inductance (µH) DCR (mΩ) Manufacturer Manufacturer P/N Case Size (mm) 2.2 16.1 Sumida CDMC6D28NP-2R2M 6.50 x 7.25 x 3.00 0.56 10 Coilcraft DO1813H-561ML 6.10 x 8.89 x 5.00 0.47 3.3 Coilcraft HA3619-471ALC 7.0 x 7.0 x 3.0 0.68 4.8 Coilcraft HA3619-681ALC 7.0 x 7.0 x 3.0 1.0 7.5 Coilcraft HA3619-102ALC 7.0 x 7.0 x 3.0 1.2 9.4 Coilcraft HA3619-122ALC 7.0 x 7.0 x 3.
PAGE 21
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 1. Minimize area of switched current loops. There are two loops where currents are switched at high di/dt slew rates in a buck regulator. The first loop represents the path taken by AC current flowing during the high side PFET on time.
PAGE 22
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com VIN U1 LO LM2854 RF CIN CO EN FB AVIN CF VOUT SW PVIN SS AGND PGND RFB1 CSS RCOMP CCOMP RFB2 Table 5. LM2854 500kHz Bill of Materials, VIN = 5V, VOUT = 3.3V, IOUT(MAX) = 4A, Optimized for Efficiency Ref Des Description Case Size Manufacturer Manufacturer P/N U1 Synchronous Buck Regulator HTSSOP-16 Texas Instruments LM2854MHX-500 CIN 47 µF, X5R, 10V 1210 TDK C3225X5R1A476M CO 100 µF, X5R, 6.
PAGE 23
LM2854 www.ti.com SNVS560C – MARCH 2008 – REVISED APRIL 2013 Table 7. LM2854 1 MHz Bill of Materials, VIN = 3.3V, VOUT = 0.8V, IOUT (MAX) = 4A, Optimized for Solution Size and Transient Response Ref Des Description Case Size Manufacturer Manufacturer P/N U1 Synchronous Buck Regulator HTSSOP-16 Texas Instruments LM2854MHX-1000 CIN 47 µF, X5R, 6.3V 1206 TDK C3216X5R0J476M CO 47 µF, X5R, 6.3V 1206 TDK C3216X5R0J476M LO 0.47 µH, 14.5 mΩ, 7A 4.06 x 4.45 x 2.
PAGE 24
LM2854 SNVS560C – MARCH 2008 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision B (April 2013) to Revision C • 24 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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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 LM2854MHX-1000/NOPB HTSSOP PWP 16 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.0 Q1 LM2854MHX-500/NOPB HTSSOP PWP 16 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.
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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) LM2854MHX-1000/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.0 LM2854MHX-500/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.
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MECHANICAL DATA PWP0016A MXA16A (Rev A) www.ti.
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