IX9907N datasheet(8/10 Pages) IXYS

8 / 10 page

INTEGRATED CIRCUITS DIVISION

IX9907

www.ixysic.com

R02

The variation in AC line voltage is sensed by way of

the auxiliary winding and an internal clamp and

current sense circuit. When the power switch is on, a

negative voltage proportional to the line voltage is

coupled to the auxiliary winding; the IX9907 will hold

the ZCV pin very close to ground during this time. The

line voltage is thus sensed indirectly through the

current in RZCV1. This current is given by:

The device uses IZCV to vary the VCS limit as shown in

Figure 4. The actual implementation is digital and is

shown below.

Figure 4 VCS vs. IZC

2.2.4 Protection Functions

The IX9907 provides comprehensive protection

features. They are summarized in the table below:

OUTPUT OVER-VOLTAGE

During the power switch off-time the auxiliary winding

voltage (VAUX) will swing positive and in proportion to

the secondary voltage. VAUX is connected to ZCV

through a resistor divider. If the voltage at ZCV

exceeds a preset threshold (VZCVOVP) for longer than

the blanking time (tZCVOVP), then the IC is latched off.

SHORTED WINDING

If the voltage at CS exceeds a preset threshold

(VCSSW) during the power switch on time the device is

latched off.

OVER-TEMPERATURE

If the die temperature exceeds 140°C, then the device

will enter the Auto-Restart Mode.

VCC OVER-VOLTAGE / UNDER-VOLTAGE

The IX9907 continuously monitors the VCC voltage. In

case of an over-voltage event, the power switch is

turned off and VCC will begin to fall. Once VCC goes

below VCCoff (10.5V nominal), and is recharged up to

VCCon (18.0V nominal), the device initiates a new

soft-start. For an under-voltage event the operation is

the same except that the sequence begins with

VCC < VCCoff so the power switch is off and VCC starts

to be charged through an external transistor. This

operation describes the Auto-Restart Mode.

During Latch-Off Mode, the line voltage must be

turned off and on again to begin normal operation.

ZCV



ZCV1



-----------------------------

ZC (µA)

200

600

1000

1400

1800

2200

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

CS vs. IZC

Fault Condition

Action Taken

Output Over-Voltage

Power Switch Latched Off

Shorted Winding

Power Switch Latched Off

Over-Temperature

Auto-Restart Mode

VCC Over-Voltage

Power Switch Latched Off

VCC Under-Voltage

Auto-Restart Mode

IX9907N Datasheet(PDF) 8 Page - IXYS Corporation

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