TS4305BEVB [SEMTECH]

Synchronous FET Controller;


型号：	TS4305BEVB
厂家：	SEMTECH CORPORATION
描述：	Synchronous FET Controller
文件：	总11页 (文件大小：684K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

TS4305BM

Synchronous FET Controller

HIGH RELIABILITY PRODUCTS

Features

Description

TS4305BM is a synchronous rectifier controller for AC-DC

power supply’s secondary side rectification.



Current-sense control for low or high-side

synchronous rectifiers

Rectifier turn on/off thresholds set with external

resistors

Minimum ON and OFF time to minimize GATE turn-

on oscillation

Specifications



Drives low or high side N-channel MOSFET

Sync-FET control based on current sensing in low or

high-side sense resistor



Wide supply range 8V to 24V

Gate drive internally limited to 10V

2A sink, 1A source gate drive

4mm x 5mm SOIC-8 package

Product is lead-free, Halogen Free, RoHS / WEEE



-55°C to +125°C T_Joperation

Operation to 24V

2A/1A sink/source gate drive

10V gate drive capability

100ns propagation delay between current sense to

GATE drive

compliant



Military temperature range



180μA (typical) quiescent current in low power mode

Under voltage lock out protection

Over temperature shut down (TSD) protection

Applications



LLC converters

Flyback converters

Typical Application Circuit

Vout

GND

Snubber

Rsense

22Ω

VCC

Flyback

Converter

Controller

Rhyst

TS4305BM

VSS

ISET

CS_GND

Ciset

DRIVE

GATE

VCC

Rgain

1Meg

ISENSE

VDD_BYP

GND

Cvccbypass

Cbypass

Vout

feedback

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Final Datasheet

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Pin Configuration

SOIC-8

(Top View)

Pin Configuration

SOIC-8 Pin #

Pin Name

Function

Description

CS_GND

Current Sense

Power Bypass

Vendor Test Mode

Ground

Current sense resistor high-side terminal

Current sense resistor low-side terminal

External bypass capacitor for internal 5V VDD supply

Tie to VCC through 1Meg resistor

Circuit Common

VDD_BYP

GND

VCC

Power Input

Supply voltage

GATE

ISET

FET Gate Drive

Current Sense Output

Gate drive, regulated voltage swing

Current sense in voltage form using Rfeedback

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Functional Block Diagram

Functional Diagram Configured in QR Flyback application

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Absolute Maximum Ratings

Over operating free–air temperature range unless otherwise noted (1, 2)

Parameter

Value

-0.3 to 26

-0.3 to 12

-0.3 to 5.5

+/-2k

Unit

VCC

GATE

ISET, CS, HI, VDD_BYP

Electrostatic Discharge – Human Body Model

Electrostatic Discharge – Charge Device Model

Reflow or solder Temperature (soldering, 10 seconds)

+/-500

260

C

(1) Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only and functional

operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to

absolute–maximum–rated conditions for extended periods may affect device reliability.

(2) All voltage values are with respect to GND.

Thermal Characteristics SOIC-8

Symbol

_JA

Parameter

Value

153

Unit

°C/W

°C

Thermal Resistance Junction to Air (1)

Storage Temperature Range

Maximum Junction Temperature

Operating Junction Temperature Range

T_STG

T_{J MAX}

T_J

-65 to 150

150

°C

-55 to 125

°C

(1) Assumes 8LD SOIC mounted on a 1-layer FR4 2S2P JEDEC board as per JESD51-7 with 13.5 inch²of 1 oz Cu.

Recommended Operating Conditions

Symbol

VCC

Parameter

Input Operating Voltage

Min

Typ

Max

Unit

V/ms

ꢀF

CS_dv/dt

CS_Input

C_VCCBYP1

C_VCCBYP2

Cbyp

CS Input Slew Rate

CS Input voltage with respect to GND

VCC Bypass Capacitor, appropriate voltage rating per VCC

Internal 5V VDD Bypass Capacitor

Maximum Gate Drive Switching Frequency

100

ꢀF

F_switch

150

kHz

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Electrical Characteristics

T_J= 25°C for typical, T_J= -55°C to 125°C, unless otherwise noted

Symbol

Parameter

Condition

Min

Typ

Max

Unit

Current Sense Amplifier

1.99

2.01

2.05

T_J=0°C to +85°C

VREF

2.0V Comparator reference

1.965

T_J=-55°C to +125°C

Supply

VCC

I_supply

V_LGC

Supply voltage

Quiescent supply current

Internal LV supply for logic

300

ꢀA

CS amp = Off during lockout time period

180

T_SD

Thermal shutdown temperature⁽¹⁾

135

°C

Under Voltage Lock Out

V_{UVLO_ON}

V_{UVLO_OFF}

V_{UVLO_hyst}

UV Turn On Threshold (VCC)

10V Gate Drive

9.5

1.0

UV Turn Off Threshold (VCC)

UVLO hysteresis

7.5

8.5

0.35

Gate Drive

V_GATE

Gate drive voltage

10V Gate Drive, VCC > 13V

VCC>13V, Gate=10V, T_J=25°C, IL=50mA

VCC>13V, Gate=10V, T_J=25°C

7.75

7.2

2.1

3.1

R_DRVHI

Gate drive source resistance

R_DRVLO

Gate drive sink resistance

Propagation delay from CS to

GATE

t_{prop_dly}

-20mV step, R_sense=5mΩ, R_gain=5Ω, R_feedback=10kΩ

Ton__pulse

Toff_blanking

Minimum gate ON pulse width

Minimum gate OFF blanking width

0.8

1.0

1.3

2.3

1.8

4.6

ꢀs

(1) Not tested in production

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Detailed Description of Operation

TS4305BM is intended for use on the secondary side of a power supply to drive a synchronous MOSFET. Unlike traditional

synchronous MOSFET controllers, the TS4305BM uses an architecture that synchronizes the rectification FET with the

secondary-side current as opposed to the secondary side voltage. Because secondary side current and voltage are not

necessarily in phase, the zero current detection method yields to a more efficient operation as opposed to operation with

voltage detection only.

Synchronous Rectifier Control

The TS4305BM uses a current mirror in conjunction with a high-sensitivity, low-offset voltage op-amp specifically designed

for sensing voltages near the low-side supply rail. This op-amp operates over a small range of input voltage suited specifically

for converting the voltage across a low-ohmic sense resistor to current. The equivalent circuit is shown below with typical

values for external components:

TS4305BM

In the above figure, the syncFET current flows through an external 5mΩ. There is also an external gain resistor Rgain = 5Ω and

a feedback resistor Rfeedback = 10kΩ. The amplifier inside the TS4305BM holds the voltage at the CS pin close to the GND

pin over a small operating range in which i_{sync_FET}is positive. Over this operating range, the voltage at ISET will be equal to

(i_{sync_FET}x5mΩ)x(10kΩ/5Ω).

TS4305BM contains a comparator that compares the voltage at ISET to an internal reference which is set to 2.0V at T_J=25°C.

In the example shown above, when VREF = 2V, the current trip level would be 200mA. This level can be adjusted by changing

Rsense, Rgain, and Rfeedback.

A hysteresis resistor can also be connected between the gate drive output and ISET to provide hysteresis in the ON/OFF trip

values. In this case, the gate turn on is expected when I_{sync_FET}is greater than:

2 ∗ ꢅꢆꢇꢈꢉ

Isync_{ꢀꢁꢂꢃꢄ}

≳

ꢖ

ꢊꢅꢋꢌꢌꢍꢎꢇꢏꢐ| ꢅꢑꢒꢓꢔꢌꢕꢌꢓꢈꢓ ∗ ꢅꢓꢌꢉꢓꢌ

Using the example values Rgain = 5Ω, Rsense=5mΩ, Rfeedback = 10kΩ, Rhysteresis=100kΩ,ꢗIsync_{ꢀꢁꢂꢃꢄ}≳ 220ꢘꢙ.

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The gate will turn off when I_{sync_FET}falls below the level according to:

2.0

ꢞꢆꢇꢔꢌ ꢝ 2.0

ꢛꢜ

ꢝ

ꢟ ∗ ꢅꢆꢇꢈꢉꢠ

ꢅꢋꢌꢌꢍꢎꢇꢏꢐ ꢅꢑꢒꢓꢔꢌꢕꢌꢓꢈꢓ

Isync_{ꢀꢁꢂꢃꢚꢚ}

≲

ꢅꢓꢌꢉꢓꢌ

Which yields Isync_{ꢀꢁꢂꢃꢚꢚ}≲ 120ꢘꢙ using the same example values with the Vgate=10V gate drive option.

If the signal frequency on the ISET pin is above approximately 200kHz at 27°C (~150kHz at -40°C and ~300kHz at 125°C), the

gate driver output will latch low to prevent the synchronous FET from operating. This condition is maintained until VCC is

power cycled.

TS4305BM can also be configured for sensing voltages on the high-side supply rail. One possible implementation can be

accomplished by powering TS4305BM through an auxiliary winding and diode-capacitor filter as shown below. Alternative

charge pump schemes can also be contemplated.

High-side Rectification with auxiliary winding and diode-capacitor filter to power TS4305BM

TS4305BM

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Rev 2.0

Application Schematic

Component Schematic

Notes

Value

1MegΩ

2Ω

HI pin tie off to VCC

Gate resistor

RCS

RISET

RHYS

10Ω

Snubber resistor, sized for proper power

Sense resistor

5mΩ

5.1Ω

10kΩ

100kΩ

1μF

10μF

22pF

10μF

1nF

Rgain resistor

Iset resistor

Hysteresis resistor

Internal 5V filter capacitor

25V VCC filter capacitor

Snubber capacitor, rated for proper Vds

Power NMOS, with proper Vds rating

100V schottky diode

TS4305BM SOIC, 10V Gate Drive

TS4305BM

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Rev 2.0

Package Drawing: SOIC-8

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Package Marking: SOIC-8

Landing Pattern: SOIC-8

Ordering Information

Device Part Number

TS4305BMSTRT

TS4305BEVB

Description

Package

SOIC-8

10V Gate Drive, 8ms lockout period

TS4305B evaluation board ⁽¹⁾

Tape & Reel (2,500 parts/reel)

(1)

The evaluation board is populated with industrial temperature grade device

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October 25 , 2017

IMPORTANT NOTICE

Information relating to this product and the application or design described herein is believed to be reliable, however such

information is provided as a guide only and Semtech assumes no liability for any errors in this document, or for the

application or design described herein. Semtech reserves the right to make changes to the product or this document at any

time without notice. Buyers should obtain the latest relevant information before placing orders and should verify that such

information is current and complete. Semtech warrants performance of its products to the specifications applicable at the

time of sale, and all sales are made in accordance with Semtech’s standard terms and conditions of sale.

SEMTECH PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-

SUPPORT APPLICATIONS, DEVICES OR SYSTEMS, OR IN NUCLEAR APPLICATIONS IN WHICH THE FAILURE COULD BE

REASONABLY EXPECTED TO RESULT IN PERSONAL INJURY, LOSS OF LIFE OR SEVERE PROPERTY OR ENVIRONMENTAL

DAMAGE. INCLUSION OF SEMTECH PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE

CUSTOMER’S OWN RISK. Should a customer purchase or use Semtech products for any such unauthorized application, the

customer shall indemnify and hold Semtech and its officers, employees, subsidiaries, affiliates, and distributors harmless

against all claims, costs damages and attorney fees which could arise.

The Semtech name and logo are registered trademarks of the Semtech Corporation. All other trademarks and trade names

mentioned may be marks and names of Semtech or their respective companies. Semtech reserves the right to make changes

to, or discontinue any products described in this document without further notice. Semtech makes no warranty,

representation or guarantee, express or implied, regarding the suitability of its products for any particular purpose. All rights

reserved.

Contact Information

Semtech Corporation

200 Flynn Road, Camarillo, CA 93012

Phone: (805) 498-2111, Fax: (805) 498-3804

www.semtech.com

TS4305BM

Final Datasheet

October 25 , 2017

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Rev 2.0

TS4305BEVB [SEMTECH]

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