2QR4765Z 查看數據表（PDF） - Infineon Technologies

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2QR4765Z

Off-Line SMPS Quasi-Resonant PWM Controller with integrated 650V CoolMOS® and startup cell in DIP-7

Infineon Technologies 

CoolSET® - Q1

ICE2QR4765Z

Functional Description

immediately after leaving Active Burst Mode. This is

helpful to decrease the output voltage undershoot.

VFB

VFBLB

VFBBOn

VFBBOff

Entering

Active Burst

Mode

Leaving

Active Burst

Mode

VFBEB

time to 7th zero and

t

VCS

blanking Window (tBEB)

1.0V

VCSB

Current limit level

during Active Burst

Mode

VVCC

t

VVCCoff

VO

t

Max. Ripple < 1%

IC is reset and the main power switch is then kept off.

After the VCC voltage falls below the threshold VVCCoff,

the startup cell is activated. The VCC capacitor is then

charged up. Once the voltage exceeds the threshold

VVCCon, the IC begins to operate with a new soft-start.

In case of open control loop or output over load, the

feedback voltage will be pulled up. After a blanking time

of 24ms, the IC enters auto-restart mode. The blanking

time here enables the converter to provide a max.

power in case the increase in VFB is due to a sudden

load increase. During off-time of the power switch, the

voltage at the zero-crossing pin is monitored for output

over-voltage detection. If the voltage is higher than the

preset threshold vZCOVP, the IC is latched off after the

preset blanking time. This latch off mode can only be

reset if the Vcc <6.23V.

If the junction temperature of IC exceeds 140 °C, the IC

enters into autorestart mode (OTP).

If the voltage at the current sensing pin is higher than

the preset threshold vCSSW during on-time of the power

switch, the IC is latched off. This is short-winding

protection.

During latch-off protection mode, the VCC voltage

drops to 10.5V and then the startup cell is activated.

The VCC voltage is then charged to 18V. The startup

cell is shut down again. This action repeats again and

again.

There is also a maximum on time limitation

implemented inside the ICE2QR4765. Once the gate

voltage is high and longer than tOnMAx, the switch is

turned off immediately.

t

Figure 8 Signals in Active Burst Mode

3.6

Protection Functions

The IC provides full protection functions. The following

table summarizes these protection functions.

Table 2 Protection features

VCC Overvoltage

VCC Undervoltage

Overload/Open Loop

Over temperature

Output Overvoltage

Short Winding

Auto Restart Mode

Auto Restart Mode

Auto Restart Mode

Auto Restart Mode

Latched Off Mode

Latched Off Mode

During operation, the VCC voltage is continuously

monitored. In case of an under- or an over-voltage, the

Version 2.1

11

August 30, 2011

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