EM8671 [EXCELLIANCE]

HV Start-up Green-mode PWM Controller with Brown-Out Protection;


型号：	EM8671
厂家：	Excelliance MOS
描述：	HV Start-up Green-mode PWM Controller with Brown-Out Protection
文件：	总13页 (文件大小：307K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

EM8671/A

HV Start-up Green-mode PWM Controller with Brown-Out Protection

General Description

Features

EM8671/A is a high performance, low cost, HV

Start-up, current mode PWM controller with green

mode power saving. The EM8671/A integrates

functions of Soft Start(SS), Under Voltage

Lockout(UVLO), Leading Edge Blanking(LEB),

internal Over Temperature Protection(OTP),

internal slope compensation. The EM8671/A also

features more protection like Over Load

Protection(OLP) and Over Voltage Protection(OVP)

to prevent circuit damage occurred under

abnormal conditions. The EM8671/A also has line

under-voltage protection (Brown-out Protection).

ꢀ

700V High Voltage Start up Circuit

Current Mode Control

Soft Start Function

Built-in Slope Compensation

Internal Leading-edge Blanking

Brown in/out Protection

Over Voltage Protection (OVP) on VCC pin

Over Load Protection (OLP)

Cycle-by-cycle Current Limit

Feedback Open Protection

Internal Over Temperature Protection (OTP)

Constant Output Power Limit (Full AC Input

Range)

ꢀ

Excellent EMI performance

Ordering Information

Part Number Package

Deep burst CS level

Applications

EM8671G

EM8671G7

EM8671AG

EM8671AG7

SOP-8

SOP-7

SOP-8

SOP-7

0.3V

0.1V

ꢀ

LCD Monitor Power Supply

Open-Frame SMPS

Typical Application Circuit

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EM8671/A

Pin Configuration

Pin Assignment

Pin Number

Pin Name

Pin Function

SOP-8

SOP-7

Ground.

GND

Voltage feedback pin. By connecting a photo-coupler to close the control loop and

achieve the regulation.

COMP

Line voltage detection. Use for brown-out protection, and Line OCP compensation.

Senses the primary current.

BNO

IC Power Supply Pin.

VCC

GATE

Gate drive output to drive the external MOSFET.

No Internal Connection.

For start-up, this pin is pulled high to the line input or the bulk capacitor via

resistors.

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EM8671/A

Function Block Diagram

VCC

BꢀO

0.9V

OVP

Control

Logic

OTP

OLP

26V

UVLO

Vbias

16V / 10V

Green

mode

COMP

Oscillator

Max duty

GATE

Soft

start

Soft

Driver

Line compensation

OCP

PWM

comparator

LEB

Slope

Comp

GꢀD

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EM8671/A

Absolute Maximum Ratings

(Note1)

ꢀ Supply Input Voltage, VCC ------------------------------------------------------------------------ 30V

ꢀ Gate pin------------------------------------------------------------------------------------------------ 30V

ꢀ HV pin--------------------------------------------------------------------------------------------------- 700V

ꢀ BNO, COMP, CS Pin --------------------------------------------------------------------------------- - 0.3V to 6.5V

ꢀ Power Dissipation, PD @ TA = 25℃

SOP 8 --------------------------------------------------------------------------------------------------- 0.4W

SOP7 --------------------------------------------------------------------------------------------------- 0.4W

ꢀ Package Thermal Resistance

SOP 8 -------------------------------------------------------------------------------------------------- 160℃/W

SOP 7 -------------------------------------------------------------------------------------------------- 160℃/W

ꢀ Junction Temperature ----------------------------------------------------------------------------- 150℃

ꢀ Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------- 260℃

ꢀ Storage Temperature Range --------------------------------------------------------------------- -65℃ to 150℃

ꢀ ESD Susceptibility

(Note2)

HBM (Human Body Mode) ------------------------------------------------------------------------ 3KV

MM (Machine Mode) -------------------------------------------------------------------------------- 250V

ꢀ Gate Output Current---------------------------------------------------------------------------------- 500mA

Recommended Operating Conditions

(Note3)

ꢀ Supply Input Voltage, VCC ----------------------------------------------------------------------- 11V to 25V

ꢀ V_CCCapacitor ---------------------------------------------------------------------------------------- 4.7uF to 47uF

ꢀ Junction Temperature Range--------------------------------------------------------------------- -40℃ to 125℃

ꢀ Ambient Temperature Range-------------------------------------------------------------------- -40℃ to 85℃

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Electrical Characteristics

(V_CC=16V, T_A=25℃, unless otherwise specified)

Parameter

VCC Section

Symbol

Test Conditions

VCC=V_TH-ON-0.5V

VCC=15V, V_COMP=0V,

Min

Typ

Max

Units

VCC OVP Protect voltage

Start up current

V_OVP

I_START

VCC On Threshold Voltage

VCC Off Threshold Voltage

Operating Supply Current 1

V_TH-ON

V_TH-OFF

I_CC-OP1

VCC=15V, V_COMP=3V,

C_GATE=1nF

Operating Supply Current 2

Operating Supply Current 3

I_CC-OP2

I_CC-OP3

2.5

0.5

VCC=15V,

Protection triggerred

Gate Section

Rising Time

Falling Time

HV Section

T_R

T_F

C_L= 1nF

100

160

VCC=V_TH-ON-0.5V

V_HV=50V

HV Current Source

I_HV

VCC=V_TH-ON+0.5V

V_HV=700V

Off-State Leakage

I_leakage

Current-Sense Section

V_BNO=1V

V_BNO=3V

0.8

0.65

200

0.85

0.7

0.9

0.75

400

Maximum Internal Current

Setpoint

V_CSLim

Leading Edge Blanking Time

Propagation Delay Time

Soft-Start Period

T_LEB

T_PD

T_SS

300

100

2.5

Internal Oscillator

Oscillation Frequency

Maximum Duty

f_OSC

KHz

D_max

Green mode minimum frequency

Frequency variation vs. VCC

KHz

VCC=11V to 25V

-20℃ to 105℃

(Note4)

Frequency variation vs.

Temperature

COMP Section

COMP short to GND current

Open loop COMP voltage

I_COMP

V_COMP=0V

150

250

5.2

350

V_COMP

COMP pin open

COMP voltage to CS voltage

Attenuation

1 / 2.5

1 / 3

1 / 3.5

V/V

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EM8671/A

Green mode COMP Threshold

Voltage

V_Green

1.8

1.3

COMP voltage for zero duty

V_COMP-ZD

BNO Section

PWM Turn On Voltage

V_BNO-ON

0.81

0.86

0.91

PWM Turn Off Voltage

V_{BNO_OFF}

V_BNO-ON– 0.1

Protection Section

Open loop protection delay time T_delay

4.0

140

Open loop protection COMP Trip

voltage

V_OLP

Internal Temperature Shutdown T_SD

℃

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. Devices are ESD sensitive. Handling precaution is recommended.

Note 3. The device is not guaranteed to function outside its operating conditions.

Note 4. Guaranteed by design.

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Typical Operating Characteristics

Temperature(℃)

Fig1. UVLO (on) vs. Temperature

Fig2. UVLO (off) vs. Temperature

Temperature(℃)

Fig3. Frequency vs. Temperature.

Fig4. Green Mode Frequency vs. Temperature.

Vbno = 1V

Vbno = 3V

Temperature(℃)

Fig5. V_CSLIMvs. Temperature.

Fig6. Start Up Current vs. Temperature.

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Temperature(℃)

Fig7. OVP vs. Temperature.

Fig8. V_OLP-Tripvs. Temperature.

Temperature(℃)

Fig9. Comp Open Voltage vs. Temperature.

Fig10. Max Duty vs Temperature.

V_BNO

V_CC

Fig11. V_CSLIMvs. V_BNO

Fig12. Frequency vs. V_CC.

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EM8671/A

Functional Description

UVLO

An UVLO comparator is implemented in EM8671/A

to monitor the VCC pin voltage. As shown in Fig. 13,

a hysteresis is built in to prevent the shutdown

from the voltage drop during startup. The UVLO

(on) and UVLO (off) are setting at 16V and 10V,

respectively.

INPUT

C_VCC

GATE

VCC

EM8671/A

GꢀD

Fig. 14

Switching Frequency

To guarantee accurate frequency, EM8671/A is

trimmed to 7% tolerance. The internal oscillator

also generates slope compensation, 75% maximum

duty limit.

Fig. 13

Leading Edge Blanking (LEB)

Each time the power MOSFET turn on, the MOSFET

C_OSS, secondary rectifier reverse recovery current

and gate driver sourcing current comprise the

current spike. To avoid premature termination of

the switching pulse, a leading edge blanking time is

built in. During the blanking time (300nS), the

PWM comparator is off and cannot switch off the

gate driver. It is recommended to adopt a smaller

R-C filter (as show ad Fig.15) for high power

application to avoid the total spike width over

300nS leading edge blanking time.

Startup Operation

Fig. 14 shows a typical HV startup circuit and

transformer auxiliary winding for the EM8671/A

application, it consumes only startup current

(typical 45uA) and the startup current drawn from

the HV pin to charge the VCC capacitor (C_VCC).

When VCC reaches UVLO (on) voltage, EM8671/A

begins switching and the HV startup current

switches off. Then, the power required is supplied

from the transformer auxiliary winding. The

hysteresis of UVLO (off) provides more holdup time,

which allows using a small capacitor for VCC.

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EM8671/A

conserves the energy.

The EM8671/A adjusts the switching mode

according to the load condition, the COMP pin

voltage drops below Deep Burst mode in-threshold

level (typical 1.3V). Device enters Deep Burst Mode

Control. The Gate drive output remains at off state

to minimize the switching loss and reduces the

standby power consumption. And when the COMP

pin voltage exceed the burst mode on threshold

level (typical 1.4V). The Gate drive output starts

active. The COMP pin voltage immediately

increases if there is a high load. When the COMP

pin voltage exceed the Deep Burst mode

out-threshold level (typical 1.5V), the device goes

to normal mode. During the Deep Burst mode, the

CS level is controlled to 0.3V for EM8671. (0.1V for

EM8671A) Fig 16 shows the signals of Deep Burst

mode.

Fig. 15

Soft Start

The EM8671/A has an internal soft-start circuit that

increases cycle-by-cycle current limit comparator

inverting input voltage slowly after it starts. The

typical soft-start time is 2mS. The pulse width to

the power MOSFET is progressively increased to

establish the correct working conditions for

transformers, rectifier diodes and capacitors. The

voltage on the output capacitors is progressively

increased with the intention of smoothly

establishing the required output voltage. It also

helps prevent transformer saturation and reduces

the stress on the secondary diode during startup.

VCC

COMP

1.5V

1.4V

1.3V

Vcs

0.3 / 0.1V

Deep Burst

Slope compensation

In the conventional application, the problem of the

stability is a critical issue for current mode

controlling, when it operates in high than 50% of

the duty cycle. The EM8671/A built in saw-tooth

slope compensation. So it requires no extra

component.

Burst

Fig. 16

Protection

The EM8671/A provides many protection functions

that intend to protect system from being damaged.

All the protection functions are listed as below:

Deep Burst Mode Operation

At no load or light load condition, majority of the

power dissipation in switching power supply is

form switching loss on the power MOSFET, the

core loss of the transformer and the loss on the

snubber. The magnitude of power loss is in

proportion to the number of switching events

within a fixed period of time. Reducing switching

events leads reduction on the power loss and

ꢀ Cycle-by-cycle current limit

The EM8671/A has over-current protection

thresholds. It is for cycle-by-cycle current limit,

which turns off MOSFET for the remainder of

the switching cycle when the sensing voltage of

MOSFET current reaches the threshold.

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EM8671/A

VCC

OVP level

ꢀ Over-load / Open-loop Protection (OLP)

When feedback loop is open, as shown in Fig. 17,

no current flows through the opto-coupler

transistor, the EM8671/A pulls up the COMP pin

voltage to 5.2V.

UVLO(on)

UVLO(off)

When the COMP pin voltage is above 4.0V

longer than 56mS, OLP is triggered. This

protection is also triggered when the SMPS

output drops below the normal value longer

than 56mS due to the overload condition.

Gate out

No Switch out

Fig. 18

ꢀ Internal Over-Temperature Protection (OTP)

Internal 140℃comparator will provide over

temperature protection (OTP). OTP will not

shutdown system. It stops the system from

switching until the VCC is below the UVLO (off)

threshold voltage, the system will hiccup.

Fig. 17

ꢀ Over Voltage Protection (OVP) on VCC

The V_GSratings of the HV power MOSFETs are

often limited up to max 30V. To prevent the V_GS

from the fault condition, the EM8671/A are

implemented a Over-Voltage-Protection (OVP)

on VCC. Whenever the VCC voltage is high than

the OVP threshold voltage (28V), the output

gate drive will be shutdown to shop the

switching of the power MOSFET until the next

UVLO (on).

The Over-Voltage-Protection on VCC function in

EM8671/A is an auto-restart type protection. If

the OVP condition is not released, the VCC will

tripped the OVP level again and re-shutdown

the gate output. The VCC is working as a hiccup

mode as shown in Fig. 18. On the other hand, if

the OVP condition is removed, the VCC level will

go back to normal level and the output will

automatically return to the normal operation.

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EM8671/A

Ordering & Marking Information

Device Name: EM8671G for SOP-8

EM8671G: Device Name

8671

ABCDEFG: Date Code

ABCDEFG

Device Name: EM8671G7 for SOP-7

8671

ABCDEFG

EM8671G7: Device Name

ABCDEFG: Date Code

Device Name: EM8671AG for SOP-8

8671A

ABCDEFG

EM8671AG: Device Name

ABCDEFG: Date Code

Device Name: EM8671AG7 for SOP-7

8671A

ABCDEFG

EM8671AG7: Device Name

ABCDEFG: Date Code

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EM8671/A

Outline Drawing

SOP-8

Dimension in mm

Dimension

Min.

4.70

3.70

5.80

0.33

1.20

0.08

0.40

0.19

0.25

0∘

Typ.

Max.

1.27

5.10

4.10

6.20

0.51

1.62

0.28

0.83

0.26

0.50

8∘

SOP-7

Dimension in mm

Dimension

Min.

4.70

3.70

5.80

0.33

1.20

0.08

0.40

0.19

0.25

0∘

Typ.

1.27

Max.

5.10

4.10

6.20

0.51

1.62

0.28

0.83

0.26

0.50

8∘

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EM8671 [EXCELLIANCE]

相关型号：

EM8671A

EM8671AG

EM8671AG7

EM8671G

EM8671G7

EM8672

EM8672G

EM8672G7

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EM8931

EM8931J