EC1466|60V, 800mA, 480kHz Non-Synchronous Buck Converter


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​​  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ 60V, 800mA, 480KHz Non-synchronous Buck Converter

EC1466

 

 

 

 

General Description

The EC1466 is a monolithic, stepdown, switch mode converter with a builtin power MOSFET. It achieves a 0.8A peakoutput current over input supply 10V60V with excellent load and line regulation. Currentmode operation provides a fast transient response and eases loop stabilization. Fault condition protections include

cyclebycycle current limiting and thermal shutdown. The EC1466 requires a minimal number of readilyavailable external components. The EC1466 is available in a SOT236 package.

 

Features

0.8A Peak Output Current

0.7Ω Internal Power MOSFET

Stable with LowESR Ceramic Output Capacitors

Up to 91% Efficiency

0.1μA Shutdown Mode

Fixed 480KHz Frequency

Thermal Shutdown

CyclebyCycle OverCurrent Protection

11V to 60V Operating Input Range

Max duty 90%

Available in a SOT236 Package

 

Applications

Power Meters

Distributed Power Systems

Battery Chargers

PreRegulator for Linear Regulators

WLED Drivers

 

Package Type

 

 

 

 

SOT23-6

 

Pin Configurations

 

 

 

 

 

 

 

 

 

(Top view)

 

 

 

 

Pin Description

Pin Number

Pin Name

Description

 

1

 

BST

Bootstrap. Connect a capacitor between the SW and BS pins to form a floating supply across the ​​ power ​​ switch ​​ driver. ​​ This ​​ capacitor ​​ drives ​​ the power ​​ switch’s ​​ gate ​​ above ​​ the ​​ supply voltage.

 

2

 

GND

Ground.  ​​​​ Voltage  ​​​​ reference  ​​​​ for  ​​​​ the  ​​​​ regulated  ​​​​ output  ​​​​ voltage.  ​​​​ Requires  ​​​​ special  ​​​​ layout considerations. Isolate this node from the D1 to C1 ground path to prevent switching current spikes from inducing.

 

3

 

FB

Feedback. Sets the output voltage. Connect to the tap of an external resistor divider from the output to GND. The frequency foldback comparator lowers the oscillator frequency when the FB voltage is below 300mV to prevent currentlimit runaway during a shortcircuit fault.

 

4

 

EN

On/Off. Pull EN above 1.35V to turn the device ON. For automatic enable, connect to VIN using

a 1MΩ resistor.

 

5

 

VIN

Supply Voltage. The EC1466 operates from a 10Vto60V unregulated input. Requires C1 to

prevent large voltage spikes from appearing at the input.

 

6

 

SW

Power Switching Output. It is the Drain of the NChannel power MOSFET to supply power to

the output LC filter.

 

Ordering ​​ Information

EC1466 ​​ XX ​​ X ​​ X

 

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

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

 ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ B3SOT23-6  ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​​​  ​​ ​​ ​​ ​​ ​​ ​​ ​​​​ 

 

Part Number

Package

Marking

Marking Information

EC1466B3GR

SOT23-6

1466k

  • Starting with underlined 4 a bar is for production year 2012. The next bar is mark on top of 6

is for year 2013. The next bar is mark on bottom of 6 is for year 2014. The next bar is mark on top of 6 is year for 2015. The  naming pattern continues with consecutive characters for later years.

2.    k is the week of production. The big  ​​ ​​ ​​​​ 

 ​​ ​​ ​​ ​​ ​​ ​​​​ character of A~Z is for the week of  ​​​​ 

 ​​ ​​ ​​ ​​ ​​ ​​​​ 1~26, and small a~z is for the week  ​​​​ 

 ​​ ​​ ​​ ​​ ​​ ​​​​ of 27~52.

 

 

 

 

 

 

 

 

 

Function Block

 

 

 

 

 

 

 

 

 

 

Symbol

Parameter

Rating

Unit

VIN

VIN Supply VoltageVIN to Gnd

0.3 ~ 60

V

VSW

SW to GND Voltage

0.3 to VIN+0.3

V

 

VBS

 

BS to GND Voltage

 

VSW 0.3 ~ VSW +6

 

V

 

 

All Other Pins

 

0.3 ~ 6

 

V

 

PD

 

Power Dissipation

 

Internally Limited

 

W

 

TJ

 

Junction Temperature

 

150

ºC

 

TSTG

 

Storage Temperature

 

65 ~ 150

ºC

 

TSDR

 

Maximum Lead Soldering Temperature (10 Seconds)

 

260

ºC

Figure1 Function Block Diagram of EC1466

 

Absolute Maximum Ratings

Note 1:

Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

 

Thermal Characteristics

 

Symbol

 

Parameter

 

Typical Value

 

Unit

 

θJA

JunctiontoAmbient Resistance in free air (Note 2)

SOT-23-6

 

250

 

°C/W

Note 2:

θJA is measured with the component mounted on a high effective thermal conductivity test board in free air.

 

Recommended Operation Conditions

 

Symbol

 

Parameter

 

Range

 

Unit

VIN

 

VIN Supply Voltage

 

11 ~ 60

 

V

 

VOUT

 

Converter Output Voltage

 

VFB ~ VIN*90%

 

V

 

 

Operating Junction Temp

 

‐40 ~ 125

oC

Note 3:

​​ Refer to the typical application circuit

 

 

Electrical Characteristics

Unless otherwise specified, these specifications apply over VIN=12V, VEN=3V and TA = 25ºC.

Symbol

Parameter

Test Conditions

 

Min

 

Typ

 

Max

 

Unit

 

VFB

 

Feedback Voltage

 

10V ​​  VIN  ​​​​  60V

 

0.792

 

0.812

 

0.832

 

V

 

IFB

 

Feedback Current

 

VFB = 0.85V

 

 

 

0.1

µA

 

RDS(ON)

SwitchOn Resistance

 

 

 

0.7

 

 

Ω

 

ISW_LKG

Switch Leakage

 

VEN=0V,VSW=0V

 

 

 

1

µA

 

ILIM

 

Current Limit

 

 

 

1.25

 

 

A

 

fSW

 

Oscillator Frequency

 

VFB=0.6V

 

380

 

480

 

580

 

KHZ

 

fSW_F

 

Foldback Frequency

 

VFB=0V

 

 

120

 

 

KHZ

 

DMAX

 

Maximum Duty Cycle

 

VFB=0.6V

 

 

90

 

 

%

 

TON

 

Minimum ON‐Time

 

 

 

100

 

 

ns

 

VUVLO_R

 

UnderVoltage Lockout

Threshold, Rising

 

 

 

7.5

 

8.5

 

V

 

VUVLO_F

 

UnderVoltage Lockout

Threshold, Falling

 

 

 

7.1

 

 

V

 

VUVLO_HYS

 

UnderVoltage Lockout

Threshold,Hysteresis

 

 

 

0.4

 

 

V

 

VEN_R

 

EN Threshold, Rising

 

 

 

1.35

 

 

V

 

VEN_F

 

EN Threshold, Falling

 

 

 

1.17

 

 

V

 

VEN_HYS

 

EN Threshold, Hysteresis

 

 

 

180

 

 

mv

 

IEN

 

EN Input Current

 

VEN=2V

 

 

3.1

 

µA

 

VEN=0V

 

 

0.1

 

µA

 

IS

 

Supply Current (Shutdown)

 

VEN=0V

 

 

0.1

 

1

µA

 

IQ

 

Supply Current (Quiescent)

 

VEN=2V,VFB=1V

 

 

0.73

 

0.85

 

mA

 

TSD

 

Thermal Shutdown

 

 

 

165

 

 

oC

 

TSD_HYS

 

Thermal Shutdown Hysteresis

 

 

 

20

 

 

oC

 

Typical Operating Characteristics

 

 

 

 

 

 

 

 

 

 

 

 

 

OPERATION

The EC1466 is a current mode buck regulator. That is, the EA output voltage is proportional to the peak inductor current.

At the beginning of a cycle, M1 is off. The EA output voltage is higher than the current sense amplifier output, and the current comparator’s output is low. The rising edge of the 480KHz CLK signal sets the RS FlipFlop. Its output turns on M1 thus connecting the SW pin and inductor to the input supply.

The increasing inductor current is sensed and amplified by the Current Sense Amplifier. Ramp compensation is summed to the Current Sense Amplifier output and compared to the Error Amplifier output by the PWM Comparator. When the sum of the Current Sense Amplifier output and the Slope Compensation signal exceeds the EA output voltage, the RS FlipFlop is reset and M1 is turned off. The external Schottky rectifier diode (D1) conducts the inductor current.

If the sum of the Current Sense Amplifier output and the Slope Compensation signal does not exceed the EA output for a whole cycle, then the falling edge of the CLK resets the FlipFlop.

The output of the Error Amplifier integrates the voltage difference between the feedback and the 0.812V bandgap reference. The polarity is such that lower than 0.812V FB pin voltage increases the EA output voltage. Since the EA output voltage is proportional to the peak inductor current, an increase in its voltage also increases current delivered to the output.

 

Application Information

Setting Output Voltage

The external resistor divider sets the output voltage (see the Typical ​​ Application ​​ schematic). ​​ Table ​​ 1 ​​ lists ​​ resistors ​​ for common ​​ output ​​ voltages. ​​ The ​​ feedback ​​ resistor ​​ (R2) ​​ also sets  ​​​​ the  ​​​​ feedback  ​​​​ loop  ​​​​ bandwidth  ​​​​ with  ​​​​ the  ​​​​ internal compensation capacitor (see Figure 1). R1 is:

 

 

 

Table 1:Resistor Selection for Common output voltages

VOUT(V)

R1(KΩ)

R2(KΩ)

1.8

102(1%)

124(1%)

2.5

59(1%)

124(1%)

3.3

40.2(1%)

124(1%)

5

23.7(1%)

124(1%)

 

Selecting the Inductor

Use an inductor with a DC current rating at least 25% percent higher than the maximum load current for most applications. For best efficiency, the inductor’s DC resistance should be less than 200mΩ. For most designs, the required inductance value can be derived from the following equation.

 

 

 

Where ΔIL is the inductor ripple current.

Choose the inductor ripple current to be 30% of the maximum load current. The maximum inductor peak current is:

 

 

 

Under lightload conditions (below 100mA), use a largerinductance to improve efficiency.

 

 

 

 

 

 

 

Selecting the Input Capacitor

The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. The input capacitor impedance at the switching frequency should be less than the input source impedance to prevent high-frequencyswitching current from passing through the input. Use ceramic capacitors with X5R or X7R dielectrics for their low ESRs and small temperature coefficients. For most applications, a 4.7μF capacitor will sufficient.

 

Selecting the Output Capacitor

The output capacitor keeps the output voltage ripple small and ensures feedback loop stability. The output capacitor impedance should be low at the switching frequency. Use ceramic capacitors with X5R or X7R dielectrics for their low

ESR characteristics. For most applications, a 22μF ceramic capacitor will sufficient.

 

PCB Layout Guide

PCB layout is very important to stability. Please follow these guidelines and use Figure 2 as reference.

1) Keep the path of switching current short and minimize the loop area formed by the input capacitor, highside MOSFET, and Schottky diode.

2) Keep the connection from the power groundSchottky diodeSW pin as short and wide as possible.

3) Ensure all feedback connections are short and direct. Place the feedback resistors and compensation components as close to the chip as possible.

4) Route SW away from sensitive analog areas such as FB.

5) Connect IN, SW, and especially GND to large copper areas to cool the chip for improved thermal performance and longterm reliability. For single layer PCBs, avoid soldering the exposed pad.