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LMZ23608

www.ti.com

SNVS708F –MARCH 2011–REVISED OCTOBER 2013

LMZ23608 8A SIMPLE SWITCHER® Power Module with 36V Maximum Input Voltage and

Current Sharing

Check for Samples: LMZ23608

FEATURES

DESCRIPTION

• Integrated Shielded Inductor

The LMZ23608 SIMPLE SWITCHER© power module

• Simple PCB Layout

is an easy-to-use step-down DC-DC solution capable

of driving up to 8A load. The LMZ23608 is available

• Frequency Synchronization Input (350 kHz to

in an innovative package that enhances thermal

600 kHz)

performance and allows for hand or machine

• Current Sharing Capability

soldering.

• Flexible Startup Sequencing Using External

The LMZ23608 can accept an input voltage rail

Soft-start, Tracking and Precision Enable

between 6V and 36V and deliver an adjustable and

• Protection Against Inrush Currents and Faults

highly accurate output voltage as low as 0.8V. The

such as Input UVLO and Output Short Circuit

LMZ23608 only requires two external resistors and

three external capacitors to complete the power

• – 40°C to 125°C Junction Temperature Range

solution. The LMZ23608 is a reliable and robust

• Single Exposed Pad and Standard Pinout for

design with the following protection features: thermal

Easy Mounting and Manufacturing

shutdown, input under-voltage lockout, output over-

• Fully Enabled for Webench® Power Designer

voltage protection, short-circuit protection, output

current limit, and allows startup into a pre-biased

• Pin Compatible with LMZ22010/08,

output. The sync input allows synchronization over

LMZ12010/08, LMZ23610/06H, and

the 350 to 600 kHz switching frequency range.

LMZ13610/08/06H

ELECTRICAL SPECIFICATIONS

APPLICATIONS

• 40W Maximum Total Output Power

• Point of Load Conversions from 12V and 24V

Input Rail • Up to 8A Output Current

• Time Critical Projects • Input Voltage Range 6V to 36V

• Space Constrained / High Thermal • Output Voltage Range 0.8V to 6V

Requirement Applications

• Efficiency up to 92%

• Negative Output Voltage Applications

(See AN-2027 SNVA425) PERFORMANCE BENEFITS

• High Efficiency Reduces System Heat

Generation

• Low Radiated Emissions (EMI) Complies with

EN55022 Class B Standard

(2)

• Only 7 External Components

• Low Output Voltage Ripple

• No External Heat Sink Required

• Simple Current Sharing for Higher Current

Figure 1. Easy to use 11 pin package

15 x 17.79 x 5.9 mm (0.59 x 0.7 x 0.232 in)

Applications

= 9.9 °C/W, θ

= 1.0 °C/W

(1)

RoHS Compliant

Peak Reflow Case Temp = 245°C

Power Module SMT Guidelines

(2) EN 55022:2006, +A1:2007, FCC Part 15 Subpart B, tested on

(1) θ

measured on a 75mm x 90mm four layer PCB. Evaluation Board with EMI configuration

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 (32 pages)

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LMZ23608 www.ti.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com System Performance Efficiency VIN = 24V VOUT = 3.3V 100 EFFICIENCY (%) 90 80 70 60 50 40 30 24 Vin 20 0 1 2 3 4 5 6 OUTPUT CURRENT (A) 7 8 Thermal derating curve VIN = 24V, VOUT = 3.3V MAXIMUM OUTPUT CURRENT (A) 10 8 6 4 2 JA = 9.9 °C/W JA = 6.8 °C/W JA = 5.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Simplified Application Schematic VOUT 6V 5V 3.3V 2.5V 1.8V 1.5V 1.2V 1.0V 0.8V VOUT SH SS FB AGND PGND EN SYNC VIN VIN LMZ23608 RFBT 15.4k 5.62k 3.32k 2.26k 1.87k 1.00k 1.07k 1.62k 0 RFBB VIN Range 2.37k 8.5...36V 1.07k 7...36V 1.07k 6...36V 1.07k 6...36V 1.50k 6...36V 1.13k 6...36V 2.05k 6...36V 6.49k 6...36V 4.02k 6...36V VOUT Share Clock CFF 4.7 nF (OPT) Enable RFBT See Table CSS CIN 0.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Pin Descriptions Pin Name Description 1, 2 VIN 3 SYNC Sync Input — Apply a CMOS logic level square wave whose frequency is between 350 kHz and 600 kHz to synchronize the PWM operating frequency to an external frequency source. When not using synchronization this pin must be tied to ground. The module free running PWM frequency is 350 kHz. 4 EN Enable — Input to the precision enable comparator. Rising threshold is 1.274V typical.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Electrical Characteristics Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature (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.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Typical Performance Characteristics Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. Efficiency 5.0V output @ 25°C Dissipation 5.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. Efficiency 1.8V output @ 25°C Dissipation 1.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. Dissipation 1.0V output @ 25°C 10 80 9 70 8 DISSIPATION (W) EFFICIENCY (%) Efficiency 1.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. Dissipation 2.5V output @ 85°C 10 90 9 80 8 DISSIPATION (W) EFFICIENCY (%) Efficiency 2.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. Dissipation 1.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. θJA vs copper heat sinking area Thermal derating VIN = 24V, VOUT = 3.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. Output ripple 12VIN, 1.2VOUT @ Full Load, BW = 20 MHz Output ripple 12VIN, 1.2VOUT@ Full Load, BW = 250 MHz Figure 39. Figure 40.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Typical Performance Characteristics (continued) Unless otherwise specified, the following conditions apply: VIN = 12V; CIN = three x 10μF + 47nF X7R Ceramic; COUT = two x 330μF Specialty Polymer + 47 uF Ceramic + 47nF Ceramic; CFF = 4.7nF; Tambient = 25° C for waveforms. All indicated temperatures are ambient. 3.3VOUT Soft Start, no CSS 3.3VOUT Soft Start, CSS = 0.47uF Figure 45. Figure 46.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com BLOCK DIAGRAM Linear Regulator 2M VIN 1 3 3 CIN EN 2 350 kHz PWM SS 2.2 uH VOUT VREF 3 RFBT CINint 1 SYNC CSS CBST COUT FB 2 Comp RFBB SH Filter AGND Regulator IC EP/ PGND Internal Passives Figure 47.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 DESIGN STEPS FOR THE LMZ23608 APPLICATION The LMZ23608 is fully supported by Webench® which offers: component selection, electrical and thermal simulations. Additionally, there are both evaluation and demonstration boards that may be used as a starting point for design. The following list of steps can be used to manually design the LMZ23608 application. All references to values refer to the typical applications schematic Figure 56.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com INT-VCC (5V) VIN 13 PA 2.0M RENT 42.2k RENH ENABLE RUN 100: 5.1V RENB 12.7k 1.274V Figure 48. Enable input detail OUTPUT VOLTAGE SELECTION Output voltage is determined by a divider of two resistors connected between VOUT and AGND. The midpoint of the divider is connected to the FB input. The regulated output voltage determined by the external divider resistors RFBT and RFBB is: VOUT = 0.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 TRACKING SUPPLY DIVIDER OPTION The tracking function allows the module to be connected as a slave supply to a primary voltage rail (often the 3.3V system rail) where the slave module output voltage is lower than that of the master. Proper configuration allows the slave rail to power up coincident with the master rail such that the voltage difference between the rails during ramp-up is small (i.e. <0.15V typ).
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Note that the stability requirement for minimum output capacitance must always be met. One recommended output capacitor combination is two 330μF, 15 mOhm ESR tantalum polymer capacitors connected in parallel with a 47 uF 6.3V X5R ceramic. This combination provides excellent performance that may exceed the requirements of certain applications. Additionally some small 47nF ceramic capacitors can be used for high frequency EMI suppression.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 To reach θCA = 18.23, the PCB is required to dissipate heat effectively. With no airflow and no external heat-sink, a good estimate of the required board area covered by 2 oz. copper on both the top and bottom metal layers is: Board Area_cm2 8 500 . °C x cm 2 TCA W (15) As a result, approximately 27.42 square cm of 2 oz copper on top and bottom layers is the minimum required area for the example PCB design. This is 5.23 x 5.23 cm (2.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com 2. Have a single point ground. The ground connections for the feedback, soft-start, and enable components should be routed to the AGND pin of the device. This prevents any switched or load currents from flowing in the analog ground traces. If not properly handled, poor grounding can result in degraded load regulation or erratic output voltage ripple behavior. Additionally provide a single point ground connection from pin 4 (AGND) to EP/PGND.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 In a current sharing system using two or more modules, the slaves have their error amp circuitry disconnected. The master over-rides the error amplifier outputs of the slaves. This signal is then compared to each module’s individual current sense circuitry. Due to this, the current sense gain of the entire system increases according to the number of modules slaved to the master.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com OUTPUT OVER-VOLTAGE PROTECTION If the voltage at FB is greater than a 0.86V internal reference, the output of the error amplifier is pulled toward ground, causing VOUT to fall. CURRENT LIMIT The LMZ23608 is protected by both low side (LS) and high side (HS) current limit circuitry. The LS current limit detection is carried out during the off-time by monitoring the current through the LS synchronous MOSFET.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Figure 55. CCM and DCM Operating Modes VIN = 12V, VO = 3.3V, IO = 3A/0.3A The approximate formula for determining the DCM/CCM boundary is as follows: (VIN - VOUT) x D IDCB = 2 x L x fSW (17) The inductor internal to the module is 2.2 μH. This value was chosen as a good balance between low and high input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple current (ΔiL).
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 www.ti.com Table 1. Typical Application Bill of Materials 24 Ref Des Description Case Size Manufacturer Manufacturer P/N U1 SIMPLE SWITCHER ® PFM-11 Texas Instruments LMZ23608TZ CIN1,6 (OPT) 0.047 µF, 50V, X7R 1206 Yageo America CC1206KRX7R9BB473 CIN2,3,4 10 µF, 50V, X7R 1210 Taiyo Yuden UMK325BJ106MM-T CIN5 (OPT) CAP, AL, 150µF, 50V Radial G Panasonic EEE-FK1H151P CO1,5 (OPT) 0.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 Figure 57.
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LMZ23608 SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 • • • • www.ti.com – For all other I/O pads use a 1:1 ratio between the aperture and the land pattern recommendation Solder Paste – Use a standard SAC Alloy such as SAC 305, type 3 or higher Stencil Thickness – 0.125 to 0.15mm Reflow - Refer to solder paste supplier recommendation and optimized per board size and density Maximum number of reflows allowed is one Figure 58. Sample Reflow Profile Table 2.
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LMZ23608 www.ti.com SNVS708F – MARCH 2011 – REVISED OCTOBER 2013 REVISION HISTORY Changes from Revision E (March 2013) to Revision F Page • Added Peak Reflow Case Temp = 245°C ............................................................................................................................ 1 • Deleted 12mils ......................................................................................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 4-Oct-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LMZ23608TZE/NOPB Package Package Pins Type Drawing PFM NDY 11 SPQ 250 Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 330.0 32.4 Pack Materials-Page 1 15.45 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 18.34 6.2 20.0 32.
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PACKAGE MATERIALS INFORMATION www.ti.com 4-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMZ23608TZE/NOPB PFM NDY 11 250 367.0 367.0 55.
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MECHANICAL DATA NDY0011A BOTTOM SIDE OF PACKAGE TOP SIDE OF PACKAGE TZA11A (Rev F) www.ti.
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