Richtek R7731AGE Schematic [ru]

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R7731A

Burst Triple Mode PWM Flyback Controller

General Description

The R7731A is a high-performance, low cost, low start-up current and current mode PWM controller with burst triple mode to support green mode power saving operation. The R7731A integrates functions of soft start, Under Voltage LockOut (UVLO), Leading Edge Blanking (LEB), Over Temperature Protection (OTP) and internal slope compensation. It provides the users a superior AC/DC power application of higher efficiency, low external component counts and lower cost solution.

To protect the external power MOSFET from being damaged by supply over voltage, the R7731Aoutput driver is clamped at 12V. Furthermore, R7731A features fruitful protections like Over Load Protection (OLP) and Over Voltage Protection (OVP) to eliminate the external protection circuits and provide reliable operation. R7731A is available in SOT-23-6 and DIP-8 packages.

Ordering Information

R7731A

Package Type

E : SOT-23-6

N : DIP-8

Lead Plating System

G : Green (Halogen Free and Pb Free)

Note :

Richtek products are :

`RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

`Suitable for use in SnPb or Pb-free soldering processes.

Features

zVery Low Start-up Current (<30μA)

z10/14V UVLO

zSoft Start Function

zCurrent Mode Control

zJittering Switching Frequency

zInternal Leading Edge Blanking

zBuilt-in Slope Compensation

zBurst Triple Mode PWM for Green-Mode

zCycle-by-Cycle Current Limit

zFeedback Open Protection

zOver Voltage Protection

zOver Temperature Protection

zOver Load Protection

zSoft Driving for Reducing EMI

zDriver Capability ±200mA

zHigh Noise Immunity

zOpto-Coupler Short Protection

zRoHS Compliant and Halogen Free

Applications

zAdaptor and Battery Charger

zATX Standby Power

zSet-Top Box (STB)

zDVDand CD(R)

zTV/Monitor Standby Power

zPC Peripherals

Marking Information

R7731AGE

IDP=W

IDP= : Product Code

W : Date Code

R7731AGE

RichTek

R7731AGN : Product Number

YMDNN : Date Code

R7731A

GNYMDNN

 

R7731A-10 August 2011

www.richtek.com

1

R7731A

Pin Configurations

(TOP VIEW)

 

 

 

 

 

 

 

 

GND COMP NC

RT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GATE VDD CS

 

 

8

 

7

 

 

 

6

 

 

5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6

5

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

3

 

 

 

 

 

 

 

2

 

 

 

3

 

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GND COMP

RT

GATE

VDD

NC

 

CS

 

 

 

 

 

 

 

 

 

 

 

SOT-23-6

 

 

 

 

 

 

 

 

DIP-8

 

 

 

 

 

Typical Application Circuit

VO+ AC Mains

(90V to 265V)

VO-

RT

VDD

*

R7731A

 

COMP

GATE

 

 

 

GND

CS

 

 

 

 

 

* : See Application Information

Functional Pin Description

Pin No.

 

Pin Name

Pin Function

SOT-23-6

 

DIP8

 

 

 

 

 

 

 

 

1

 

8

GND

Ground.

 

 

 

 

 

2

 

7

COMP

Comparator Input. By connecting an opto-coupler to this pin, the peak

 

current set point is adjusted accordingly to the output power requirement.

 

 

 

 

3

 

5

RT

Set the switching frequency by connecting a resistor to GND.

4

 

4

CS

Primary Current Sense.

 

 

 

 

 

5

 

2

VDD

IC Power Supply.

 

 

 

 

 

6

 

1

GATE

Gate Driver Output to drive the external MOSFET.

--

 

3, 6

NC

No Internal Connection.

 

 

 

 

 

www.richtek.com

R7731A-10 August 2011

2

R7731A

Function Block Diagram

 

 

 

 

OVP +

VDD

 

 

 

 

POR

-

27V

 

 

Shutdown

OTP

 

 

 

 

Logic

 

 

+

 

 

 

 

 

 

 

Brown out

 

 

 

UVLO

-

14V/10V

sensing

 

 

 

 

 

 

COMP open

 

Counter

 

 

Bias &

 

 

 

 

sensing

 

 

 

 

Bandgap

OLP

 

 

Jittering Oscillator

 

 

Constant

SS

 

 

 

 

RT

 

 

Dmax

 

 

Power

 

 

 

 

 

 

 

 

 

 

 

Soft

 

 

 

 

S

 

Driver

 

 

 

 

 

 

 

 

 

-

 

Q

GATE

COMP

 

 

R

 

 

 

 

-

 

 

 

 

 

+

 

 

 

 

 

 

PWM

 

 

 

CS

Slope

comparator

 

 

 

 

 

 

 

 

 

Ramp

 

 

 

 

COMP

 

 

 

 

 

 

 

 

 

 

Burst

 

VBURL

LEB

X3

 

 

Triple Mode

 

VBURH

 

 

 

 

VDD

 

 

 

 

 

 

 

 

 

 

 

 

GND

R7731A-10 August 2011

www.richtek.com

3

R7731A

Absolute Maximum Ratings (Note 1)

z Supply Input Voltage, VDD -------------------------------------------------------------------------------------------------

−0.3V to 30V

z GATE Pin ----------------------------------------------------------------------------------------------------------------------

−0.3V to 20V

z RT, COMP, CS Pin ----------------------------------------------------------------------------------------------------------

−0.3V to 6.5V

z IDD -------------------------------------------------------------------------------------------------------------------------------

10mA

z Power Dissipation, PD @ TA = 25°C

 

SOT-23-6 ----------------------------------------------------------------------------------------------------------------------

0.4W

DIP-8 ---------------------------------------------------------------------------------------------------------------------------

0.714W

z Package Thermal Resistance (Note 2)

 

SOT-23-6, θJA -----------------------------------------------------------------------------------------------------------------

250°C/W

DIP-8, θJA ----------------------------------------------------------------------------------------------------------------------

140°C/W

z Junction Temperature -------------------------------------------------------------------------------------------------------

150°C

z Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------------------

260°C

z Storage Temperature Range ----------------------------------------------------------------------------------------------

−65°C to 150°C

z ESD Susceptibility (Note 3)

 

HBM (Human Body Mode) ------------------------------------------------------------------------------------------------

4kV

MM (Machine Mode) --------------------------------------------------------------------------------------------------------

250V

Recommended Operating Conditions

(Note 4)

z Supply Input Voltage, VDD -------------------------------------------------------------------------------------------------

12V to 25V

z Operating Frequency -------------------------------------------------------------------------------------------------------

50k to 130kHz

z Junction Temperature Range ----------------------------------------------------------------------------------------------

−40°C to 125°C

z Ambient Temperature Range ----------------------------------------------------------------------------------------------

−40°C to 85°C

Electrical Characteristics

(VDD = 15V, VDD bypass capacitor=0.1μF, RT = 100kΩ, TA = 25°C, unless otherwise specified)

 

Parameter

Symbol

Test Conditions

Min

 

Typ

 

Max

Unit

 

VDD Section

 

 

 

 

 

 

 

 

 

VDD Over Voltage Protection Level

VOVP

 

25.5

 

27

 

28.5

V

 

On Threshold Voltage

VTH_ON

 

13

 

14

 

15

V

 

VDD On/Off Hysteresis

VDD_HYS

 

3

 

4

 

5

V

 

Start-up Current

IDD_ST

VDD = VTH_ON – 0.1V

--

 

20

 

30

μA

 

Operating Current

IDD_OP

VDD = 15V, RT = 100kΩ,

--

 

1.1

 

2.2

mA

 

GATE = Open, VCOMP = 2.5V

 

 

 

 

 

 

 

 

 

 

 

 

VDD Holdup Mode Hysteresis

VDD_HYS

VCOMP < 1.6V

--

 

11.5

 

--

V

 

Ending Level

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VDD Holdup Mode Entry Level

VDD_LOW

VCOMP < 1.6V

--

 

11

 

--

V

 

VDD Clamp Voltage

VDD_CLAMP

 

--

 

29

 

--

V

 

Oscillator Section (RT pin)

 

 

 

 

 

 

 

 

 

Normal PWM Frequency

fOSC

RT = 100kΩ

60

 

65

 

70

kHz

 

 

 

 

 

 

To be continued

 

 

 

 

 

 

 

 

 

 

www.richtek.com

 

 

 

R7731A-10

August 2011

4

R7731A

Parameter

 

Symbol

Test Conditions

Min

Typ

Max

Unit

Frequency Jittering Range

 

 

 

--

±6

--

%

 

 

 

 

 

 

 

PWM Frequency Jitter Period

TJIT

For 65 kHz

--

4

--

ms

Maximum Duty Cycle

DMAX

 

70

75

80

%

Frequency Variation Versus VDD

fDV

VDD = 12V to 25V

--

--

2

%

Deviation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Frequency Variation Versus

fDT

TA = −30°C to 105°C (Note 5)

--

--

5

%

Temperature Deviation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

COMP Input Section

 

 

 

 

 

 

 

Open Loop Voltage

VCOMP_OP

COMP pin open

5.2

5.6

6

V

COMP Open-loop Protection Delay

T

OLP

R = 100kΩ

--

60

--

ms

Cycles

 

T

 

 

 

 

 

 

 

 

 

 

 

Short Circuit Current

IZERO

VCOMP = 0V

--

1.2

2.2

mA

Current-Sense Section

 

 

 

 

 

 

 

Initial Peak Current Limit Offset

VCSTH

 

0.8

0.85

0.9

V

Leading Edge Blanking Time

TLEB

 

--

420

520

ns

Propagation Delay Time

TPD

 

--

100

--

ns

GATE Section

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rising Time

TR

VDD = 15V, CL = 1nF

--

250

350

ns

Falling Time

TF

VDD = 15V, CL = 1nF

--

150

250

ns

Gate Output Clamping Voltage

VCLAMP

VDD = 22V

--

12

--

V

Over Temperature Protection

TOTP

 

140

--

--

°C

OTP Hysteresis

TOTP_HYS

 

--

30

--

°C

Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability.

Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard.

Note 3. Devices are ESD sensitive. Handling precaution is recommended.

Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Guaranteed by design.

R7731A-10 August 2011

www.richtek.com

 

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