National Semiconductor LM3150 Technical data

October 17, 2008

LM3150
SIMPLE SWITCHER® CONTROLLER, 42V Synchronous
Step-Down

LM3150 SIMPLE SWITCHER

General Description

The LM3150 SIMPLE SWITCHER® Controller is an easy to
use and simplified step down power controller capable of pro­viding up to 12A of output current in a typical application.
Operating with an input voltage range of 6V-42V, the LM3150
features an adjustable output voltage down to 0.6V. The
switching frequency is adjustable up to 1 MHz and the syn­chronous architecture provides for highly efficient designs.
The LM3150 controller employs a Constant On-Time (COT)
architecture with a proprietary Emulated Ripple Mode (ERM)
control that allows for the use of low ESR output capacitors,
which reduces overall solution size and output voltage ripple.
The Constant On-Time (COT) regulation architecture allows
for fast transient response and requires no loop compensa­tion, which reduces external component count and reduces
design complexity.

Fault protection features such as thermal shutdown, under­voltage lockout, over-voltage protection, short-circuit protec­tion, current limit, and output voltage pre-bias startup allow for
a reliable and robust solution.

The LM3150 SIMPLE SWITCHER® concept provides for an
easy to use complete design using a minimum number of ex­ternal components and National’s WEBENCH® online design
tool. WEBENCH® provides design support for every step of
the design process and includes features such as external
component calculation with a new MOSFET selector, electri­cal simulation, thermal simulation, and Build-It boards for
prototyping.

Features

PowerWise® step-down controller

■

6V to 42V Wide input voltage range

■

Adjustable output voltage down to 0.6V

■

Programmable switching frequency up to 1 MHz

■

No loop compensation required

■

Fully WEBENCH® enabled

■

Low external component count

■

Constant On-Time control

■

Ultra-fast transient response

■

Stable with low ESR capacitors

■

Output voltage pre-bias startup

■

Valley current limit

■

Programmable soft-start

■

Typical Applications

Telecom

■

Networking Equipment

■

Routers

■

Security Surveillance

■

Power Modules

■

®

CONTROLLER, 42V Synchronous Step-Down

Typical Application

30053101

SIMPLE SWITCHER® is a registered trademark of National Semiconductor Corporation

© 2008 National Semiconductor Corporation 300531 www.national.com

Connection Diagram

LM3150

eTSSOP-14

30053102

Ordering Information

Order Number Package Type NSC Package Drawing Supplied As

LM3150MH

LM3150MHE 250 Units in Tape and Reel

LM3150MHX 2500 Units in Tape and Reel

eTSSOP-14 MXA14A

94 Units per Anti-Static Tube

Pin Descriptions

Pin Name Description Function

1 VCC

2 VIN Input Supply Voltage Supply pin to the device. Nominal input range is 6V to 42V.

3 EN Enable

4 FB Feedback

5,9 SGND Signal Ground

6 SS Soft-Start

7 RON On-time Control An external resistor from VIN to this pin sets the high-side switch on-time.

8 ILIM Current Limit

10 SW Switch Node

11 HG High-Side Gate Drive

12 BST

13 LG Low-Side Gate Drive

14 PGND Power Ground

EP EP Exposed Pad

Supply Voltage for FET
Drivers

Connection for Bootstrap
Capacitor

Nominally regulated to 5.95V. Connect a 1.0 µF to 2.2 µF decoupling capacitor from
this pin to ground.

To enable the IC apply a logic high signal to this pin greater than 1.26V typical or
leave floating. To disable the part, ground the EN pin.

Internally connected to the regulation, over-voltage, and short-circuit comparators.
The regulation setting is 0.6V at this pin. Connect to feedback resistor divider between
the output and ground to set the output voltage.

Ground for all internal bias and reference circuitry. Should be connected to PGND at
a single point.

An internal 7.7 µA current source charges an external capacitor to provide the soft­start function.

Monitors current through the low-side switch and triggers current limit operation if the
inductor valley current exceeds a user defined value that is set by R
current, I

Switch pin of controller and high-gate driver lower supply rail. A boost capacitor is
also connected between this pin and BST pin

Gate drive signal to the high-side NMOS switch. The high-side gate driver voltage is
supplied by the differential voltage between the BST pin and SW pin.

High-gate driver upper supply rail. Connect a 0.33 µF-0.47 µF capacitor from SW pin
to this pin. An internal diode charges the capacitor during the high-side switch off­time. Do not connect to an external supply rail.

Gate drive signal to the low-side NMOS switch. The low-side gate driver voltage is
supplied by VCC.

Synchronous rectifier MOSFET source connection. Tie to power ground plane.
Should be tied to SGND at a single point.

Exposed die attach pad should be connected directly to SGND. Also used to help
dissipate heat out of the IC.

, sourced out of this pin during operation.

LIM-TH

and the Sense

LIM

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LM3150

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/

All Other Inputs to GND -0.3V to 7V
ESD Rating (Note 2) 2 kV
Storage Temperature Range -65°C to +150°C

Distributors for availability and specifications.

VIN, RON to GND -0.3V to 47V
SW to GND -3V to 47V
BST to SW -0.3V to 7V
BST to GND -0.3V to 52V

Electrical Characteristics Limits in standard type are for T

Operating Ratings (Note 1)

V

IN

Junction Temperature Range (TJ)

EN 0V to 5V

= 25°C only; limits in boldface type apply over the

J

6V to 42V

−40°C to + 125°C

junction temperature (TJ) range of -40°C to +125°C. 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.

Symbol Parameter Conditions Min Typ Max Units

Start-Up Regulator, VCC

C

VCC

VIN - VCC VIN - VCC Dropout Voltage

I

VCC

VCC

t

CC-UVLO-D

I

VCCL

UVLO

UVLO-HYS

I

IN

IN-SD

VCC Current Limit (Note 3) VCC = 0V

VCC Under-Voltage Lockout Threshold
(UVLO)

VCC UVLO Hysteresis VCC Decreasing 475 mV

VCC UVLO Filter Delay 3 µs

Input Operating Current

Input Operating Current, Device
Shutdown

= 1 µF, 0 mA to 40 mA 5.65 5.95 6.25

VCC

I

= 2 mA, VIN = 5.5V 40

VCC

I

= 30 mA, VIN = 5.5V 330

VCC

65 100

VCC Increasing 4.75 5.1 5.40 V

No Switching, VFB = 1V

VEN = 0V

3.5 5 mA

32 55 µA

GATE Drive

I

Q-BST

R

DS-HG-Pull-Up

R

DS-HG-Pull-Down

R

DS-LG-Pull-Up

R

DS-LG-Pull-Down

Boost Pin Leakage V

– VSW = 6V

BST

HG Drive Pull–Up On-Resistance IHG Source = 200 mA

HG Drive Pull–Down On-Resistance IHG Sink = 200 mA

LG Drive Pull–Up On-Resistance ILG Source = 200 mA

LG Drive Pull–Down On-Resistance ILG Sink = 200 mA

2 nA

5

3.4

3.4

2

Soft-Start

I

SS

I

SS-DIS

SS Pin Source Current VSS = 0V

SS Pin Discharge Current

5.9 7.7 9.5 µA

200 µA

Current Limit

I

LIM-TH

Current Limit Sense Pin Source Current

75 85 95 µA

ON/OFF Timer

t

ON

t

ON-MIN

t

OFF

VIN = 10V, RON = 100 kΩ,
VFB = 0.6V

ON Timer Pulse Width

VIN = 18V, RON = 100 kΩ,
VFB = 0.6V

VIN = 42V, RON = 100 kΩ,
VFB = 0.6V

ON Timer Minimum Pulse Width (Note 4) 200 ns

OFF Timer Minimum Pulse Width 370 525 ns

1.02

0.62

0.36

Enable Input

V

V

EN-HYS

EN

EN Pin Input Threshold Trip Point VEN Rising

EN Pin Threshold Hysteresis VEN Falling

1.14 1.20 1.26 V

120 mV

V

mV

mA

Ω

Ω

Ω

Ω

µs

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Symbol Parameter Conditions Min Typ Max Units

Regulation and Over-Voltage Comparator

LM3150

V

V

FB

FB-OV

I

FB

In-Regulation Feedback Voltage VSS > 0.6V

Feedback Over-Voltage Threshold

Feedback Bias Current

0.588 0.600 0.612 V

0.690 0.720 0.748 V

20 nA

Boost Diode

V

f

Forward Voltage I

I

BST

BST

= 2 mA

= 30 mA

0.7

1

Thermal Characteristics

T

SD

θ

JA

θ

JC

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but does not guarantee specific performance limits. For guaranteed specifications and conditions, see the Electrical Characteristics.

Note 2: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. Test Method is per JESD-22-A114.

Note 3: VCC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.

Note 4: See Applications section for minimum on-time when using MOSFETs connected to gate drivers.

Thermal Shutdown Rising 165 °C

Thermal Shutdown Hysteresis Falling 15 °C

Junction to Ambient

4 Layer JEDEC Printed Circuit
Board, 9 Vias, No Air Flow

2 Layer JEDEC Printed Circuit
Board. No Air Flow

40

140

Junction to Case No Air Flow 4 °C/W

V

°C/W

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Simplified Block Diagram

LM3150

30053103

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Typical Performance Characteristics

LM3150

Boost Diode Forward Voltage vs. Temperature

30053140

Quiescent Current vs. Temperature

I

vs. Temperature

LIM-TH

Soft-Start Current vs. Temperature

30053141

30053142

tON vs. Temperature

30053144

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30053143

tON vs. Temperature

30053145