EC5015A|2A, 40V Synchronous Step-Down Converter


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​​  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ 2A, ​​ 40V ​​ Synchronous Step-Down ​​ Converter

EC5015A

 

 

 

 

General Description

The EC5015A is a current mode monolithic buck switching regulator. Operating with an input range of 3.6V~40V,

The EC5015A delivers 2A of continuous  ​​​​ output  ​​​​ current  ​​​​ with  ​​​​ two  ​​​​ integrated N-Channel ​​ MOSFETs. ​​ 

The ​​ internal ​​ synchronous power  ​​​​ switches  ​​​​ provide  ​​​​ high  ​​​​ efficiency  ​​​​ without the ​​ use ​​ of ​​ an ​​ external ​​ Schottky

diode. ​​ At ​​ light loads,  ​​​​ regulators  ​​​​ operate  ​​​​ in  ​​​​ low  ​​​​ frequency  ​​​​ to maintain  ​​​​ high  ​​​​ efficiency  ​​​​ and  ​​​​ low  ​​​​ output  ​​​​ ripple. Current mode control provides tight load transient response and cycle-by-cycle current limit.

The EC5015A guarantees robustness with short-circuit protection, thermal protection, start-up ​​ current  ​​​​ run-away

protection, and input under voltage lockout.

The EC5015A is available in 8-pin ESOP package, which provides a compact solution with minimal ​​ external

components. ​​ The ​​ package ​​ has an exposed pad for low thermal resistance.

 

Features

3.6 V to 40 V operating input range

2A output current

Up to 94% efficiency

High efficiency (>78%) at light load

Internal Soft-Start

Fixed 440kHz Switching frequency

Input under voltage lockout

Available  ​​ ​​​​ in  ​​ ​​​​ thermally  ​​ ​​​​ enhanced  ​​ ​​​​ ESOP8 package

Start-up current run-away protection

Short circuit protection

Thermal protection

 

Applications

Distributed Power Systems

Networking Systems

FPGA, DSP, ASIC Power Supplies

Green Electronics/ Appliances

Notebook Computers

 

Typical application

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ordering/Marking Information

 

EC5015A ​​ XX ​​ X ​​ X

 

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ R:Tape & Reel

Package Type:  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ G:Green

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ MH=ESOP8  ​​ ​​ ​​ ​​ ​​ ​​ ​​​​  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ 

 

Device

Marking

Package

Information

EC5015AMHGR

JW5015A

XXXXXXX

ESOP8

XXXXXXX: ​​ Date Code

 

 

 

 

Pin Configurations

 

 

 

 

 

 

 

 

 

The pad and Pin-6 must be connected to GND.

 

 

 

Absolute Maximum Ratings

VIN, EN, SW Pin.......................................................................................................................  ​​ ​​ ​​ ​​​​ -0.3V to 44V

BST Pin.....................................................................................................................................  ​​ ​​ ​​ ​​​​ SW-0.3Vto SW+5V

All other Pins.............................................................................................................................  ​​ ​​ ​​ ​​​​ -0.3Vto 6V

Junction Temperature2) 3)........................................................................................................  ​​ ​​ ​​ ​​​​ 150ºC

Lead Temperature.....................................................................................................................  ​​ ​​ ​​ ​​​​ 260ºC

Storage Temperature.................................................................................................................  ​​ ​​ ​​​​ -65ºC to +150ºC

 

Recommended Operating Conditions

Input Voltage VIN......................................................................................................................  3.6Vto 40V

Output Voltage Vout..................................................................................................................  0.8Vto 37V

Operating Junction Temperature...............................................................................................  -40ºC to 125ºC

Thermal Performance

ESOP8 .....................................................................................................................................  50....10ºC/W

Note

1)  ​​​​ Exceeding these ratings may damage the device.

2)  ​​​​ The EC5015A guarantees robust performance from -40°C to 150°C junction temperature. The junction

temperature range specification is assured by design, characterization and correlation with statistical process

controls.

3)  ​​​​ The ​​ EC5015A ​​ includes ​​ thermal ​​ protection ​​ that ​​ is ​​ intended ​​ to ​​ protect ​​ the ​​ device ​​ in ​​ overload ​​ conditions. ​​ 

Thermal protection ​​ is ​​ active ​​ when ​​ junction ​​ temperature ​​ exceeds ​​ the ​​ maximum ​​ operating ​​ junction ​​ temperature. ​​ Continuous operation over the specified absolute maximum operating junction temperature may damage the device.

4)  ​​​​ Measured on JESD51-7, 4-layer PCB.

 

Electrical Characteristics

VIN = 12V, TA = 25ºC, unless otherwise stated.

Item

Symbol

Condition

Min.

Typ.

Max.

Units

VIN Undervoltage Lockout

Threshold

VIN_MIN

VIN falling

2.8

3.4

3.6

V

VIN Undervoltage Lockout

Hysteresis

VIN_MIN_HYST

VIN rising

140

270

360

mV

Shutdown Supply Current

ISD

VIN=40V, VEN=0V

 

0

1

µA

Supply Current

IQ

VEN=5V, VFB=1V

 

65

95

µA

Feedback Voltage

VFB

3.6V<VVIN<40V

0.788

0.8

0.812

V

Top Switch Resistance5)

RDS(ON)T

 

 

126

206

m

Bottom Switch Resistance5)

RDS(ON)B

 

 

63

103

m

Top Switch Leakage Current

ILEAK_TOP

VIN=40V, VEN=0V,

VSW=0V

 

0

1

uA

Bottom Switch Leakage

Current

ILEAK_BOT

VIN= VSW = 40V, VEN=0V

 

0

1

uA

Top Switch Current Limit5)

ILIM_TOP

Minimum Duty Cycle

3

3.7

 

A

Switch Frequency

fSW

 

220

440

660

kHz

Minimum On Time5)

TON_MIN

 

 

117

 

ns

Minimum Off Time5)

TOFF_MIN

VFB=0V

 

112

 

ns

EN shut down threshold

voltage

VEN_TH

VEN falling, FB=0V

1

1.2

1.43

V

EN shut down hysteresis

VEN_HYST

VEN rising, FB=0V

 

140

200

mV

Thermal Shutdown5)

TTSD

 

 

135

 

°C

Thermal Shutdown hysteresis5)

TTSD_HYST

 

 

15

 

°C

 

Note:

5) Guaranteed by design.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pin Description

ESOP8

Pin

Name

Description

1

SW

SW is the switching node that supplies power to the output. Connect the output LC filter from

SW to the output load.

2

BST

Bootstrap pin for top switch. A 0.1uF or larger capacitor should be connected between this pin

and the SW pin to supply current to the top switch and top switch driver.

3

BIAS/VD

Output  of  the  internal  LDO.  A  capacitor  of  2.2uF  or  larger  should  be  connected  at  VD

To ground.

4

FB

Output  feedback  pin.  FB  senses  the  output  voltage  and  is  regulated  by  the  control  loop

To 0.8V. Connect a resistive divider at FB.

5

NC

 

6/9

GND

Ground.

7

EN

Drive EN pin high to turn on the regulator and low to turn off the regulator.

8

VIN

Input  voltage  pin.  VIN supplies  power  to  the  IC.  Connect  a  3.6V to  40V supply  to  VIN 

And bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC.

 

Block Diagram

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Typical Performance Characteristics

Vin = 12V, Vo = 5V, L = 10µH, Cout = 10µF, TA = +25°C, unless otherwise noted

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Functional Description

The ​​ EC5015A ​​ is ​​ a synchronous, ​​ current-mode, step-down ​​ regulator. ​​ It ​​ regulates ​​ input ​​ voltage from ​​ 3.6V ​​ to ​​ 40V ​​ down

to ​​ an ​​ output ​​ voltage ​​ as low ​​ as ​​ 0.8V, ​​ and ​​ is ​​ capable ​​ of ​​ supplying ​​ up ​​ to 2A of load current.

Current-Mode Control

The ​​ EC5015A ​​ utilizes ​​ current-mode ​​ control ​​ to regulate ​​ the ​​ output ​​ voltage. ​​ The ​​ output ​​ voltage is ​​ measured ​​ at ​​ the ​​ FB

pin ​​ through ​​ a ​​ resistive voltage divider and the error is amplified by the internal transconductance error amplifier. Output of

the internal error amplifier is compared  ​​​​ with  ​​​​ the  ​​​​ switch  ​​​​ current  ​​​​ measured internally to control the output current limit.

 

PFM Mode

The ​​ EC5015A ​​ operates ​​ in ​​ PFM ​​ mode ​​ at ​​ light load. In PFM  mode, switch frequency is continuously controlled in proportion

to the load current, i.e. switch frequency is decreased when load current ​​ drops ​​ to ​​ boost ​​ power ​​ efficiency ​​ at light ​​ load ​​ by

reducing ​​ switch-loss, ​​ while ​​ switch frequency is increased when load current rises, minimizing both load current and output

voltage ripples.

 

Shut-Down Mode

The  ​​​​ EC5015A  ​​​​ operates  ​​​​ in  ​​​​ shut-down  ​​​​ mode when voltage at EN pin is driven below 0.3V. In shut-down ​​ mode, the ​​ entire

regulator ​​ is ​​ off ​​ and the ​​ supply ​​ current ​​ consumed ​​ by ​​ the ​​ EC5015A drops below 0.1uA.

 

Power Switch

N-Channel MOSFET switches are integrated on the EC5015A to down convert the input voltage to the regulated output voltage.

Since the top MOSFET needs a gate voltage greater than the input voltage,a boost capacitor connected between BST and SW

pins ​​ is ​​ required ​​ to ​​ drive the gate of the top switch. The boost capacitor is charged by the internal 3.3V rail when SW is low.

 

Vin Under-Voltage Protection

A ​​ resistive ​​ divider can be connected between Vin and ground, with the central tap connected to EN, so that when Vin drops to

the ​​ pre-set value, EN drops below 1.2V to trigger input under voltage lockout protection.

 

Output Current Run-Away Protection

At start-up, due to the high voltage at input and low voltage at output, current inertia of the output inductance can be easily built

up, resulting in a large start-up output current. A valley current ​​ limit ​​ is ​​ designed ​​ in ​​ the ​​ EC5015A so ​​ that ​​ only ​​ when ​​ output

current ​​ drops ​​ below the ​​ valley ​​ current ​​ limit ​​ can ​​ the ​​ bottom ​​ power switch be turned off. By such control mechanism, the

output current at start-up is well controlled.

 

Output Short Protection

When output is shorted to ground, output current rapidly reaches its peak current limit and the top power switch is turned off.

Right after the top power switch is turned off, the bottom power switch ​​ is ​​ turned ​​ on ​​ and ​​ stay on ​​ until ​​ the ​​ output current

falls below the valley current limit. When output ​​ current ​​ is ​​ below ​​ the ​​ valley ​​ current ​​ limit, the top power switch will be turned

on again and if ​​ the output short is still ​​ present, the top power switch ​​ is ​​ turned ​​ off ​​ when ​​ the ​​ peak ​​ current ​​ limit is reached

and the bottom power switch is turned ​​ on. This cycle goes on until the output short is removed and the regulator comes into

normal operation again.

 

Thermal Protection

When the temperature of ​​ the EC5015A rises above 135°C, it is forced into thermal shut-down. Only when core temperature

drops below 120°C can the regulator becomes active again.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Application Information

Output Voltage Set

The output voltage is determined by the resistor divider connected at the FB pin, and the voltage ratio is:

 

 

where VFB is the feedback voltage and VOUT is the output voltage. Choose R3 around 10k, and then R2 can be calculated by:

 

 

The following table lists the recommended values.

VOUT(V)

R3(k)

R2(k)

2.5

11.3

23.7

3.3

15.8

49.9

5

13

68.1

 

 

 

 

 

Input Capacitor

The input capacitor is used to supply the AC input current to the step-down converter and maintaining the DC input voltage.

The ripple current through the input capacitor can be calculated by:

 

 

 

where  ​​​​ ILOAD  ​​​​ is  ​​​​ the  ​​​​ load  ​​​​ current,  ​​​​ VOUT  ​​​​ is  ​​​​ the output voltage, VIN is the input voltage.

 

Thus the input capacitor can be calculated by the following equation when the input ripple voltage is determined.

 

 

where C1 is the input capacitance value, fs is the switching frequency, VIN is the input ripple voltage.

 

The input capacitor can be electrolytic, tantalum or ceramic. To minimizing the potential noise, a small X5R or X7R ceramic

capacitor, i.e.0.1uF, should be placed as close to the IC as possible when using electrolytic capacitors. A 10uF ceramic

capacitor ​​ is ​​ recommended ​​ in typical application.

 

Output Capacitor

The output capacitor is required to maintain the DC output voltage, and the capacitance value determines the output ripple

voltage. The output voltage ripple can be calculated by:

 

 

where ​​ C2 ​​ is ​​ the ​​ output ​​ capacitance value and RESR is the equivalent series resistance value of the output capacitor.

The output capacitor can be low ESR electrolytic, tantalum or ceramic. Lower ESR capacitors get lower output ripple voltage.

The output capacitors also affect the system stability and transient response, and a 22uF ceramic capacitor is recommended

in typical application.

 

 

 

 

 

 

Inductor

The inductor is used to supply constant current to the output load. The inductance determines the ripple current which affects

the efficiency and the output voltage ripple. The ripple current is typically allowed to be 30% of the maximum switch current

limit, thus the inductance value can be calculated by:

 

 

 

where VIN is the input voltage, VOUT is the output voltage, fs ​​ is the switching frequency, and IL is the peak-to-peak inductor

ripple current.

 

External Boostrap Capacitor

A boostrap capacitor is required to supply voltage to the top switch driver. A 0.1uF low ESR ceramic capacitor is recommended

To connected to the BST pin and SW pin.

 

External Bias Capacitor

A bias capacitor is required to provide compensation for the internal LDO. A 2.2uF low ESR ceramic capacitor is recommended

To connect to the BIAS pin and GND.

 

PCB Layout Note

For minimum noise problem and best EMI performance, the PCB is preferred to following the guidelines and figure 1 as

reference.

  • Place the input decoupling capacitor as close ​​ to EC5015A (VIN ​​ pin ​​ and ​​ PGND) as possible to eliminate noise at the input ​​ pin. The loop area formed by input capacitor and GND must be minimized.

  • Put the feedback trace as far away from the inductor and noisy power traces as possible.

  • Pin 9 GND must be connected to Pin 6 GND as close as possible.

  • To improve thermal conduction, put an array of ​​ vias ​​ right ​​ under ​​ the ​​ exposed ​​ pad. Use small vias (15mil barrel diameter) so that the holes can be filled during the plating process. Very large holes can cause solder-wicking’ problems during

the ​​ reflow soldering process. Use a via pitch (distance between the centers of two adjacent vias) of 40mil.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reference Design

Reference 1:

VIN  ​​​​ :3.6V ~ 40 V

VOUT:3.3V

IOUT :0~2A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reference 2:

VIN  ​​​​ :5.1V ~ 40 V

VOUT:5V

IOUT :0~2A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Package Outline

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9I18N-Rev. F003

 

 

E-CMOS Corp. (www.ecmos.com.tw)

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ 


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