EC3286|3A 32V Synchronous Rectified Step-Down Converter


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3A 32V Synchronous Rectified Step-Down Converter

EC3286

 

 

General Description

 

The EC3286 is a monolithic synchronous buck regulator. The device integrates two 90mΩ MOSFETs, and provides 3A of continuous load current over a wide input voltage of 4.75V to 32V. Current mode control provides ​​ fast transient ​​ response ​​ and ​​ cycle-by-cycle ​​ current limit.

An adjustable soft-start prevents inrush current at ​​ turn-on, and ​​ in ​​ shutdown ​​ mode ​​ the ​​ supply current drops to 1µA.The EC3286 regulates the output voltage in automatic PSM/PWM mode operation, depending on the output current, for high efficiency operation over light to full load current.

This ​​ device, available in an SOP-8(Exposed PAD) package, provides a very compact solution with minimal external components.

Features

 

●3A Output Current

●Wide 4.75V to 32V Operating Input Range

●Integrated 90mΩ Power MOSFET Switches

●Output Adjustable from 0.923V to 30V

●Up to 93% Efficiency

●Pulse Save Mode(PSM)/PWM Mode Operation

●Programmable Soft-Start

●Stable with Low ESR Ceramic Output Capacitors

●Fixed 340KHz Frequency

●Cycle-by-Cycle Over Current Protection

●Input Under Voltage Lockout

 

Applications

 

Distributed Power Systems

Networking Systems

FPGA, DSP, ASIC Power Supplies

●Green Electronics/ Appliances

Notebook Computers

 

 

 

 

 

Package Types

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1. Package Types of EC3286

EC3286

3A 32V Synchronous Rectified Step-Down Converter

 

 

Pin Configurations

 

 

 

 

 

 

 

 

 

 

Figure 2 Pin Configuration of EC3286(Top View)

 

Pin Description

 

Pin Number

Pin Name

Description

1

BS

High-Side  Gate  Drive  Boost  Input.  BS  supplies  the  drive  for  the  high-side  N-Channel

MOSFET  switch.  Connect  a  0.01µF  or  greater  capacitor  from  SW  to  BS  to  power  the

high side switch.

2

IN

Power  Input.  IN  supplies  the  power  to  the  IC,  as  well  as  the  step-down  converter

switches.  Drive  IN  with  a  4.75V  to  32V  power  source.  Bypass  IN  to  GND  with  a

suitably large capacitor to eliminate noise on the input to the IC. See Input Capacitor.

3

SW

Power Switching Output. SW is the switching node that supplies power to the output.

Connect  the  output  LC  filter  from  SW  to  the  output  load.  Note  that  a  capacitor  is

required from SW to BS to power the high-side switch.

4

GND

Ground.

5

FB

Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB

with a resistive voltage divider from  the output voltage. The feedback threshold

is 0.923V. See Setting the Output Voltage.

6

COMP

Compensation Node. COMP is used to  compensate the regulation control loop.

Connect a series  RC  network  from  COMP  to  GND  to  compensate  the regulation

control loop.   In   some   cases, an additional capacitor  from  COMP to GND  is

required. See Compensation Components.

7

EN

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to

turn on the regulator, drive it low to turn it off. Pull up with 100k resistor for

automatic startup.

8

SS

Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS

to GND to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms.

To disable the soft-start feature, leave SS unconnected.

 

 

 

 

 

 

 

 

 

Ordering Information

Part Number

Package

Marking

Marking Information

EC3286NNMHR

SOP-8L

(Exposed PAD)

EC3286

LLLLL

​​ YYWWT

LLLLL is Lot Number

YYWW is date code

T is internal tracking code

 

 

Function Block

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3 Function Block Diagram of ​​ EC3286

EC3286

3A 32V Synchronous Rectified Step-Down Converter

 

Absolute Maximum Ratings

 

Parameter

Symbol

Value

Unit

Supply Voltage

VIN

-0.3 to 32

V

Switch Node Voltage

VSW

30

V

Boost Voltage

VBS

VSW   0.3V to VSW+6V

V

Output Voltage

VOUT

0.923V to 30

V

All Other Pins

 

–0.3V to +6V

V

Operating Junction Temperature

TJ

150

ºC

Storage Temperature

TSTG

-65 to 150

ºC

Lead Temperature (Soldering, 10 sec)

TLEAD

260

ºC

ESD (HBM)

 

2000

V

MSL

 

Level3

 

Thermal Resistance-Junction to Ambient

RθJA

50

ºC / W

Thermal Resistance-Junction to Case

RθJC

10

ºC / W

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Electrical Characteristics 

VIN = 12V, Ta = 25℃ ​​ unless otherwise specified.

Parameters

Symbol

Test Condition

Min.

Typ.

Max.

Unit

Shutdown Supply Current

 

VEN = 0V

 

1

3.0

µA

Supply Current

 

VEN = 2.0V; VFB =

1.0V

 

1.3

1.5

mA

Feedback Voltage

VFB

4.75V  VIN  23V

0.900

0.923

0.946

V

Feedback Overvoltage Threshold

 

 

 

1.1

 

V

Error Amplifier Voltage Gain *

AEA

 

 

400

 

V/V

Error Amplifier Transconductance

GEA

∆IC = ±10µA

 

800

 

µA/V

High-Side Switch On Resistance *

RDS(ON)1

 

 

90

 

mΩ

Low-Side Switch On Resistance *

RDS(ON)2

 

 

90

 

mΩ

High-Side Switch Leakage

Current

 

VEN = 0V, VSW = 0V

 

 

10

µA

Upper Switch Current Limit

 

Minimum Duty Cycle

4.0

5.8

 

A

Lower Switch Current Limit

 

From Drain to Source

 

0.9

 

A

COMP to Current Sense

Transconductance

GCS

 

 

4.8

 

A/V

Oscillation Frequency

Fosc1

 

 

340

 

KHz

Short Circuit Oscillation

Frequency

Fosc2

VFB = 0V

 

100

 

KHz

Maximum Duty Cycle

DMAX

VFB = 1.0V

 

90

 

%

Minimum On Time *

 

 

 

220

 

ns

EN Shutdown Threshold Voltage

 

VEN Rising

1.1

1.5

2.0

V

EN Shutdown Threshold Voltage

Hysteresis

 

 

 

210

 

mV

EN Lockout Threshold Voltage

 

 

2.2

2.5

2.7

V

EN Lockout Hysterisis

 

 

 

210

 

mV

 

 

 

 

 

 

 

 

 

Electrical Characteristics 

VIN = 12V, Ta = 25℃ ​​ unless otherwise specified.

 

Parameters

Symbol

Test Condition

Min.

Typ.

Max.

Unit

Input Under Voltage Lockout

Threshold

 

VIN Rising

3.80

4.10

4.40

V

Input Under Voltage Lockout

Threshold Hysteresis

 

 

 

210

 

mV

Soft-Start Current

 

VSS = 0V

 

6

 

µA

Soft-Start Period

 

CSS = 0.1µF

 

15

 

ms

Thermal Shutdown   *

 

 

 

160

 

°C

 

Typical Performance Characteristics

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4. Steady State Test  ​​​​   Figure 5. Steady State Test  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​  ​​ ​​​​ 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical Performance ​​ Characteristics(Cont.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6. Startup through EnableFigure 7. Startup through Enable

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 8. Shutdown through Enable

Figure 9. Shutdown through Enable

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical Performance ​​ Characteristics(Cont.)