LM317LZ/LFT1 - NATIONAL SEMICONDUCTOR

September 2007

LM3102

SIMPLE SWITCHER® Synchronous 1MHz 2.5A

Step-Down Voltage Regulator

General Description

The LM3102 Synchronously Rectified Buck Converter fea-

tures all required functions to implement a highly efficient and

cost effective buck regulator. It is capable of supplying 2.5A

to loads with an output voltage as low as 0.8V. Dual N-Chan-

nel synchronous MOSFET switches allow a low component

count, thus reducing complexity and minimizing board size.

Different from most other COT regulators, the LM3102 does

not rely on output capacitor ESR for stability, and is designed

to work exceptionally well with ceramic and other very low

ESR output capacitors. It requires no loop compensation, re-

sults in a fast load transient response and simple circuit

implementation. The operating frequency remains nearly con-

stant with line variations due to the inverse relationship be-

tween the input voltage and the on-time. The operating

frequency can be externally programmed up to 1 MHz. Pro-

tection features include VCC under-voltage lock-out, output

over-voltage protection, thermal shutdown, and gate drive

under-voltage lock-out. The LM3102 is available in the ther-

mally enhanced eTSSOP-20 package.

Key Specifications

■Input voltage range 4.5V-42V

■2.5A output current

■0.8V, ±1.5% reference

■Integrated dual N-Channel main and synchronous

MOSFETs

■Thermally enhanced eTSSOP-20 package

Features

■Low component count and small solution size

■Stable with ceramic and other low ESR capacitors

■No loop compensation required

■High efficiency at a light load by DCM operation

■Pre-bias startup

■Ultra-fast transient response

■Programmable soft-start

■Programmable switching frequency up to 1 MHz

■Valley current limit

■Output over-voltage protection

■Precision internal reference for an adjustable output

voltage down to 0.8V

■Thermal shutdown

Typical Applications

■5VDC, 12VDC, 24VDC, 12VAC, and 24VAC systems

■Embedded Systems

■Industrial Control

■Automotive Telematics and Body Electronics

■Point of Load Regulators

■Storage Systems

■Broadband Infrastructure

■Direct Conversion from 2/3/4 Cell Lithium Batteries

Systems

Typical Application

30021301

SIMPLE SWITCHER® is a registered trademark of National Semiconductor Corporation

LM3102 SIMPLE SWITCHER® Synchronous 1MHz 2.5A Step-Down Voltage Regulator

Connection Diagram

30021302

20-lead Plastic eTSSOP

NS Package Number MXA20A

Ordering Information

Order Number Package Type NSC Package Drawing Supplied As

LM3102MH Exposed Pad TSSOP-20 MXA0020 73 units per Anti-Static Tube

LM3102MHX 2500 Units on Tape and Reel

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LM3102

Pin Descriptions

Pin Name Description Application Information

1,9,10,12,19,20 N/C No Connection These pins must be left unconnected.

2, 3 SW Switching Node Internally connected to the source of the main

MOSFET and the drain of the Synchronous MOSFET.

Connect to the inductor.

4, 5 VIN Input supply voltage Supply pin to the device. Nominal input range is 4.5V

to 42V.

6 BST Connection for bootstrap capacitor Connect a 33 nF capacitor from the SW pin to this pin.

An internal diode charges the capacitor during the main

MOSFET off-time.

7 AGND Analog Ground Ground for all internal circuitry other than the PGND

pin.

8 SS Soft-start An 8 µA internal current source charges an external

capacitor to provide the soft- start function.

11 GND Ground Must be connected to the AGND pin for normal

operation. The GND and AGND pins are not internally

connected.

13 FB Feedback Internally connected to the regulation and over-voltage

comparators. The regulation setting is 0.8V at this pin.

Connect to feedback resistors.

14 EN Enable pin Connect a voltage higher than 1.26V to enable the

regulator.

15 RON On-time Control An external resistor from the VIN pin to this pin sets the

main MOSFET on-time.

16 VCC Start-up regulator Output Nominally regulated to 6V. Connect a capacitor of not

less than 680 nF between the VCC and AGND pins for

stable operation.

17, 18 PGND Power Ground Synchronous MOSFET source connection. Tie to a

ground plane.

DAP EP Exposed Pad Thermal connection pad. Connect to the ground plane.

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LM3102

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

VIN, RON to AGND -0.3V to 43.5V

SW to AGND -0.3V to 43.5V

SW to AGND (Transient) -2V (< 100ns)

VIN to SW -0.3V to 43.5V

BST to SW -0.3V to 7V

All Other Inputs to AGND -0.3V to 7V

ESD Rating (Note 2)

Human Body Model ±2kV

Storage Temperature Range -65°C to +150°C

Junction Temperature (TJ) 150°C

Operating Ratings (Note 1)

Supply Voltage Range (VIN) 4.5V to 42V

Junction Temperature Range (TJ)−40°C to +125°C

Thermal Resistance (θJC) (Note 3) 6.5°C/W

Electrical Characteristics Specifications with standard type are for TJ = 25°C only; limits in boldface type apply

over the full Operating Junction Temperature (TJ) range. Minimum and Maximum limits are guaranteed 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. Unless otherwise stated the following conditions apply: VIN = 18V, VOUT = 3.3V.

Symbol Parameter Conditions Min Typ Max Units

Start-Up Regulator, VCC

VCC VCC output voltage CCC = 680nF, no load 5.0 6.0 7.2 V

VIN - VCC VIN - VCC dropout voltage ICC = 2mA 50 200 mV

ICC = 20mA 350 570

IVCCL VCC current limit (Note 4) VCC = 0V 40 65 mA

VCC-UVLO VCC under-voltage lockout threshold

(UVLO)

VIN increasing 3.6 3.75 3.9 V

VCC-UVLO-HYS VCC UVLO hysteresis VIN decreasing 130 mV

tVCC-UVLO-D VCC UVLO filter delay 3 µs

IIN IIN operating current No switching, VFB = 1V 0.7 1mA

IIN-SD IIN operating current, Device shutdown VEN = 0V 25 40 µA

Switching Characteristics

RDS-UP-ON Main MOSFET RDS(on) 0.18 0.375 Ω

RDS- DN-ON Syn. MOSFET RDS(on) 0.11 0.225 Ω

VG-UVLO Gate drive voltage UVLO VBST - VSW increasing 3.3 4V

Soft-start

ISS SS pin source current VSS = 0.5V 6810 µA

Current Limit

ICL Syn. MOSFET current limit threshold 2.7 A

ON/OFF Timer

ton ON timer pulse width VIN = 10V, RON = 100 kΩ 1.38 µs

VIN = 30V, RON = 100 kΩ 0.47

ton-MIN ON timer minimum pulse width 150 ns

toff OFF timer pulse width 260 ns

Enable Input

VEN EN Pin input threshold VEN rising 1.13 1.18 1.23 V

VEN-HYS Enable threshold hysteresis VEN falling 90 mV

Regulation and Over-Voltage Comparator

VFB In-regulation feedback voltage VSS ≥ 0.8V

TJ = −40°C to +125°C

0.784 0.8 0.816 V

VSS ≥ 0.8V

TJ = 0°C to +125°C

0.788 0.812

VFB-OV Feedback over-voltage threshold 0.888 0.920 0.945 V

IFB 5 nA

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LM3102

Symbol Parameter Conditions Min Typ Max Units

Thermal Shutdown

TSD Thermal shutdown temperature TJ rising 165 °C

TSD-HYS Thermal shutdown temperature

hysteresis

TJ falling 20 °C

Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the

device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.

Note 3: θJC measurements are performed in general accordance with Mil-Std 883B, Method 1012.1 and utilizes the copper heat sink technique. Copper Heat

Sink @ 60°C.

Note 4: VCC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.

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LM3102

Typical Performance Characteristics

All curves are taken at VIN = 18V with the configuration in the typical application circuit for VOUT = 3.3V shown in this datasheet.

TA = 25°C, unless otherwise specified.

Quiescent Current, IIN vs VIN

30021303

VCC vs ICC

30021304

VCC vs VIN

30021305

ton vs VIN

30021306

Switching Frequency, fSW vs VIN

30021307

VFB vs Temperature

30021308

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LM3102

RDS(on) vs Temperature

30021309

Efficiency vs Load Current

(VOUT = 3.3V)

30021310

VOUT Regulation vs Load Current

(VOUT = 3.3V)

30021311

Efficiency vs Load Current

(VOUT = 0.8V)

30021312

VOUT Regulation vs Load Current

(VOUT = 0.8V)

30021313

Power Up

(VOUT = 3.3V, 2.5A Loaded)

30021339

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LM3102

Enable Transient

(VOUT = 3.3V, 2.5A Loaded)

30021314

Shutdown Transient

(VOUT = 3.3V, 2.5A Loaded)

30021315

Continuous Mode Operation

(VOUT = 3.3V, 2.5A Loaded)

30021316

Discontinuous Mode Operation

(VOUT = 3.3V, 0.025A Loaded)

30021317

DCM to CCM Transition

(VOUT = 3.3V, 0.15A - 2.5A Load)

30021318

Load Transient

(VOUT = 3.3V, 0.25A - 2.5A Load, Current slew-rate: 2.5A/µs)

30021319

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LM3102

Simplified Functional Block Diagram

30021320

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LM3102

Functional Description

The LM3102 Step Down Switching Regulator features all re-

quired functions to implement a cost effective, efficient buck

power converter capable of supplying 2.5A to a load. It con-

tains Dual N-Channel main and synchronous MOSFETs. The

Constant ON-Time (COT) regulation scheme requires no loop

compensation, results in fast load transient response and

simple circuit implementation. The regulator can function

properly even with an all ceramic output capacitor network,

and does not rely on the output capacitor’s ESR for stability.

The operating frequency remains constant with line variations

due to the inverse relationship between the input voltage and

the on-time. The valley current limit detection circuit, with the

limit set internally at 2.7A, inhibits the main MOSFET until the

inductor current level subsides.

The LM3102 can be applied in numerous applications and

can operate efficiently for inputs as high as 42V. Protection

features include output over-voltage protection, thermal shut-

down, VCC under-voltage lock-out, gate drive under-voltage

lock-out. The LM3102 is available in the thermally enhanced

eTSSOP-20 package.

COT Control Circuit Overview

COT control is based on a comparator and a one-shot on-

timer, with the output voltage feedback (feeding to the FB pin)

compared with an internal reference of 0.8V. If the voltage of

the FB pin is below the reference, the main MOSFET is turned

on for a fixed on-time determined by a programming resistor

RON and the input voltage VIN, upon which the on-time varies

inversely. Following the on-time, the main MOSFET remains

off for a minimum of 260 ns. Then, if the voltage of the FB pin

is below the reference, the main MOSFET is turned on again

for another on-time period. The switching will continue to

achieve regulation.

The regulator will operate in the discontinuous conduction

mode (DCM) at a light load, and the continuous conduction

mode (CCM) with a heavy load. In the DCM, the current

through the inductor starts at zero and ramps up to a peak

during the on-time, and then ramps back to zero before the

end of the off-time. It remains zero and the load current is

supplied entirely by the output capacitor. The next on-time

period starts when the voltage at the FB pin falls below the

internal reference. The operating frequency in the DCM is

lower and varies larger with the load current as compared with

the CCM. Conversion efficiency is maintained since conduc-

tion loss and switching loss are reduced with the reduction in

the load and the switching frequency respectively. The oper-

ating frequency in the DCM can be calculated approximately

as follows:

(1)

In the continuous conduction mode (CCM), the current flows

through the inductor in the entire switching cycle, and never

reaches zero during the off-time. The operating frequency re-

mains relatively constant with load and line variations. The

CCM operating frequency can be calculated approximately as

follows:

(2)

The output voltage is set by two external resistors RFB1 and

RFB2. The regulated output voltage is

VOUT = 0.8V x (RFB1 + RFB2)/RFB2 (3)

Startup Regulator (VCC)

A startup regulator is integrated within the LM3102. The input

pin VIN can be connected directly to a line voltage up to 42V.

The VCC output regulates at 6V, and is current limited to 65

mA. Upon power up, the regulator sources current into an ex-

ternal capacitor CVCC, which is connected to the VCC pin. For

stability, CVCC must be at least 680 nF. When the voltage on

the VCC pin is higher than the under-voltage lock-out (UVLO)

threshold of 3.75V, the main MOSFET is enabled and the SS

pin is released to allow the soft-start capacitor CSS to charge.

The minimum input voltage is determined by the dropout volt-

age of the regulator and the VCC UVLO falling threshold

(≊3.7V). If VIN is less than ≊4.0V, the regulator shuts off and

VCC goes to zero.

Regulation Comparator

The feedback voltage at the FB pin is compared to a 0.8V

internal reference. In normal operation (the output voltage is

regulated), an on-time period is initiated when the voltage at

the FB pin falls below 0.8V. The main MOSFET stays on for

the on-time, causing the output voltage and consequently the

voltage of the FB pin to rise above 0.8V. After the on-time

period, the main MOSFET stays off until the voltage of the FB

pin falls below 0.8V again. Bias current at the FB pin is nom-

inally 5 nA.

Zero Coil Current Detect

The current of the synchronous MOSFET is monitored by a

zero coil current detection circuit which inhibits the syn-

chronous MOSFET when its current reaches zero until the

next on-time. This circuit enables the DCM operation, which

improves the efficiency at a light load.

Over-Voltage Comparator

The voltage at the FB pin is compared to a 0.92V internal

reference. If it rises above 0.92V, the on-time is immediately

terminated. This condition is known as over-voltage protec-

tion (OVP). It can occur if the input voltage or the output load

changes suddenly. Once the OVP is activated, the main

MOSFET remains off until the voltage at the FB pin falls below

0.92V. The synchronous MOSFET will stay on to discharge

the inductor until the inductor current reduces to zero, and

then switch off.

ON-Time Timer, Shutdown

The on-time of the LM3102 main MOSFET is determined by

the resistor RON and the input voltage VIN. It is calculated as

follows:

(4)

The inverse relationship of ton and VIN gives a nearly constant

frequency as VIN is varied. RON should be selected such that

the on-time at maximum VIN is greater than 150 ns. The on-

timer has a limiter to ensure a minimum of 150 ns for ton. This

limits the maximum operating frequency, which is governed

by the following equation:

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LM3102

(5)

The LM3102 can be remotely shutdown by pulling the voltage

of the EN pin below 1V. In this shutdown mode, the SS pin is

internally grounded, the on-timer is disabled, and bias cur-

rents are reduced. Releasing the EN pin allows normal oper-

ation to resume because the EN pin is internally pulled up.

30021325

FIGURE 1. Shutdown Implementation

Current Limit

Current limit detection is carried out during the off-time by

monitoring the re-circulating current through the synchronous

MOSFET. Referring to the Functional Block Diagram, when

the main MOSFET is turned off, the inductor current flows

through the load, the PGND pin and the internal synchronous

MOSFET. If this current exceeds 2.7A, the current limit com-

parator toggles, and as a result disabling the start of the next

on-time period. The next switching cycle starts when the re-

circulating current falls back below 2.7A (and the voltage at

the FB pin is below 0.8V). The inductor current is monitored

during the on-time of the synchronous MOSFET. As long as

the inductor current exceeds 2.7A, the main MOSFET will re-

main inhibited to achieve current limit. The operating frequen-

cy is lower during current limit due to a longer off-time.

Figure 2 illustrates an inductor current waveform. On aver-

age, the output current IOUT is the same as the inductor

current IL, which is the average of the rippled inductor current.

In case of current limit (the current limit portion of Figure 2),

the next on-time will not initiate until that the current drops

below 2.7A (assume the voltage at the FB pin is lower than

0.8V). During each on-time the current ramps up an amount

equal to:

(6)

During current limit, the LM3102 operates in a constant cur-

rent mode with an average output current IOUT(CL) equal to

2.7A + ILR / 2.

30021326

FIGURE 2. Inductor Current - Current Limit Operation

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LM3102

N-Channel MOSFET and Driver

The LM3102 integrates an N-Channel main MOSFET and an

associated floating high voltage main MOSFET gate driver.

The gate drive circuit works in conjunction with an external

bootstrap capacitor CBST and an internal high voltage diode.

CBST connecting between the BST and SW pins powers the

main MOSFET gate driver during the main MOSFET on-time.

During each off-time, the voltage of the SW pin falls to ap-

proximately -1V, and CBST charges from VCC through the

internal diode. The minimum off-time of 260 ns provides

enough time for charging CBST in each cycle.

Soft-Start

The soft-start feature allows the converter to gradually reach

a steady state operating point, thereby reducing startup

stresses and current surges. Upon turn-on, after VCC reaches

the under-voltage threshold, an 8 µA internal current source

charges up an external capacitor CSS connecting to the SS

pin. The ramping voltage at the SS pin (and the non-inverting

input of the regulation comparator as well) ramps up the out-

put voltage VOUT in a controlled manner.

An internal switch grounds the SS pin if any of the following

three cases happens: (i) VCC is below the under-voltage lock-

out threshold; (ii) a thermal shutdown occurs; or (iii) the EN

pin is grounded. Alternatively, the output voltage can be shut

off by connecting the SS pin to ground using an external

switch. Releasing the switch allows the SS pin to ramp up and

the output voltage to return to normal. The shutdown config-

uration is shown in Figure 3.

30021327

FIGURE 3. Alternate Shutdown Implementation

Thermal Protection

The junction temperature of the LM3102 should not exceed

the maximum limit. Thermal protection is implemented by an

internal Thermal Shutdown circuit, which activates (typically)

at 165°C to make the controller enter a low power reset state

by disabling the main MOSFET, disabling the on-timer, and

grounding the SS pin. Thermal protection helps prevent

catastrophic failures from accidental device overheating.

When the junction temperature falls back below 145°C (typi-

cal hysteresis = 20°C), the SS pin is released and normal

operation resumes.

Thermal Derating

The LM3102 is capable of supplying 2.5A below an ambient

temperature of 100°C. Under worst case operation, with ei-

ther input voltage up to 42V, operating frequency up to 1 MHz,

or voltage of the RON pin below the absolute maximum of 7V,

the LM3102 can deliver a minimum of 1.9A output current

without thermal shutdown with a PCB ground plane copper

area of 40cm2, 2 oz/Cu. Figure 4 shows a thermal derating

curve for the minimum output current without thermal shut-

down against ambient temperature up to 125°C. Obtaining

2.5A output current is possible by increasing the PCB ground

plane area, or reducing the input voltage or operating fre-

quency.

30021340

FIGURE 4. Thermal Derating Curve

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LM3102

Applications Information

EXTERNAL COMPONENTS

The following guidelines can be used to select external com-

ponents.

RFB1 and RFB2 : These resistors should be chosen from stan-

dard values in the range of 1.0 kΩ to 10 kΩ, satisfying the

following ratio:

RFB1/RFB2 = (VOUT/0.8V) - 1 (7)

For VOUT = 0.8V, the FB pin can be connected to the output

directly with a pre-load resistor drawing more than 20 µA. It is

because the converter operation needs a minimum inductor

current ripple to maintain good regulation when no load is

connected.

RON: Equation (2) can be used to select RON if a desired op-

erating frequency is selected. But the minimum value of

RON is determined by the minimum on-time. It can be calcu-

lated as follows:

(8)

If RON calculated from (2) is smaller than the minimum value

determined in (8), a lower frequency should be selected to re-

calculate RON by (2). Alternatively, VIN(MAX) can also be limited

in order to keep the frequency unchanged. The relationship

of VIN(MAX) and RON is shown in Figure 5.

On the other hand, the minimum off-time of 260 ns can limit

the maximum duty ratio. Larger RON should be selected in any

application requiring large duty ratio.

30021329

FIGURE 5. Maximum VIN for selected RON

L: The main parameter affected by the inductor is the ampli-

tude of inductor current ripple (ILR). Once ILR is selected, L can

be determined by:

(9)

where VIN is the maximum input voltage and fSW is determined

from (2).

If the output current IOUT is determined, by assuming that

IOUT = IL, the higher and lower peak of ILR can be determined.

Beware that the higher peak of ILR should not be larger than

the saturation current of the inductor and current limits of the

main and synchronous MOSFETs. Also, the lower peak of

ILR must be positive if CCM operation is required.

30021331

FIGURE 6. Inductor selection for VOUT = 3.3V

30021332

FIGURE 7. Inductor selection for VOUT = 0.8V

Figure 6 and Figure 7 show curves on inductor selection for

various VOUT and RON. For small RON, according to (8), VIN is

limited. Some curves are therefore limited as shown in the

figures.

CVCC: The capacitor on the VCC output provides not only noise

filtering and stability, but also prevents false triggering of the

VCC UVLO at the main MOSFET on/off transitions. CVCC

should be no smaller than 680 nF for stability, and should be

a good quality, low ESR, ceramic capacitor.

COUT and COUT3: COUT should generally be no smaller than

10 µF. Experimentation is usually necessary to determine the

minimum value for COUT, as the nature of the load may require

a larger value. A load which creates significant transients re-

quires a larger COUT than a fixed load.

COUT3 is a small value ceramic capacitor located close to the

LM3102 to further suppress high frequency noise at VOUT. A

100 nF capacitor is recommended.

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LM3102

CIN and CIN3: The function of CIN is to supply most of the main

MOSFET current during the on-time, and limit the voltage rip-

ple at the VIN pin, assuming that the voltage source connect-

ing to the VIN pin has finite output impedance. If the voltage

source’s dynamic impedance is high (effectively a current

source), CIN supplies the average input current, but not the

ripple current.

At the maximum load current, when the main MOSFET turns

on, the current to the VIN pin suddenly increases from zero

to the lower peak of the inductor’s ripple current and ramps

up to the higher peak value. It then drops to zero at turn-off.

The average current during the on-time is the load current.

For a worst case calculation, CIN must be capable of supplying

this average load current during the maximum on-time. CIN is

calculated from:

(10)

where IOUT is the load current, ton is the maximum on-time,

and ΔVIN is the allowable ripple voltage at VIN.

CIN3’s purpose is to help avoid transients and ringing due to

long lead inductance at the VIN pin. A low ESR 0.1 µF ceramic

chip capacitor located close to the LM3102 is recommended.

CBST: A 33 nF high quality ceramic capacitor with low ESR is

recommended for CBST since it supplies a surge current to

charge the main MOSFET gate driver at turn-on. Low ESR

also helps ensure a complete recharge during each off-time.

CSS: The capacitor at the SS pin determines the soft-start

time, i.e. the time for the reference voltage at the regulation

comparator and the output voltage to reach their final value.

The time is determined from the following equation:

(11)

CFB: If the output voltage is higher than 1.6V, CFB is needed

in the Discontinuous Conduction Mode to reduce the output

ripple. The recommended value for CFB is 10 nF.

PC BOARD LAYOUT

The LM3102 regulation, over-voltage, and current limit com-

parators are very fast so they will respond to short duration

noise pulses. Layout is therefore critical for optimum perfor-

mance. It must be as neat and compact as possible, and all

external components must be as close to their associated

pins of the LM3102 as possible. Refer to the functional block

diagram, the loop formed by CIN, the main and synchronous

MOSFET internal to the LM3102, and the PGND pin should

be as small as possible. The connection from the PGND pin

to CIN should be as short and direct as possible. Vias should

be added to connect the ground of CIN to a ground plane,

located as close to the capacitor as possible. The bootstrap

capacitor CBST should be connected as close to the SW and

BST pins as possible, and the connecting traces should be

thick. The feedback resistors and capacitor RFB1, RFB2, and

CFB should be close to the FB pin. A long trace running from

VOUT to RFB1 is generally acceptable since this is a low

impedance node. Ground RFB2 directly to the AGND pin (pin

7). The output capacitor COUT should be connected close to

the load and tied directly to the ground plane. The inductor L

should be connected close to the SW pin with as short a trace

as possible to reduce the potential for EMI (electromagnetic

interference) generation. If it is expected that the internal dis-

sipation of the LM3102 will produce excessive junction tem-

perature during normal operation, making good use of the PC

board’s ground plane can help considerably to dissipate heat.

The exposed pad on the bottom of the LM3102 IC package

can be soldered to the ground plane, which should extend out

from beneath the LM3102 to help dissipate heat. The exposed

pad is internally connected to the LM3102 IC substrate. Ad-

ditionally the use of thick traces, where possible, can help

conduct heat away from the LM3102. Using numerous vias to

connect the die attached pad to the ground plane is a good

practice. Judicious positioning of the PC board within the end

product, along with the use of any available air flow (forced or

natural convection) can help reduce the junction temperature.

30021335

Typical Application Schematic for VOUT = 3.3V

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LM3102

30021336

Typical Application Schematic for VOUT = 0.8V

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LM3102

Physical Dimensions inches (millimeters) unless otherwise noted

20-Lead Plastic eTSSOP Package

NS Package Number MXA20A

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LM3102

Notes

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LM3102

Notes

LM3102 SIMPLE SWITCHER® Synchronous 1MHz 2.5A Step-Down Voltage Regulator

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