ICE3BS03LJGXUMA1 Datasheet ICE3BS03LJGXUMA1 | P16-P18

Version 2.0 16 6 Dec 2007

F3 PWM controller

ICE3BS03LJG

Functional Description

3.7.3 Protection Modes

The IC provides several protection features which are

separated into two categories. Some enter Latched Off

Mode and the others enter Auto Restart Mode. Besides

the pre-defined protection feature for the Latch off

mode, there is also an external Latch off Enable pin for

customer defined Latch off protection features. The

Latched Off Mode can only be reset if VCC falls below

6.23V. Both modes prevent the SMPS from destructive

states.The following table shows the relationship

between possible system failures and the chosen

protection modes.

3.7.3.1 Latched Off Mode

Figure 25 Latched Off Mode

The VCC voltage is observed by comparator C1. If the

VCC voltage is > 25.5V, the overvoltage detection is

activated. It enters the latch off mode.

The internal Voltage Reference is switched off most of

the time once Latched Off Mode is entered in order to

minimize the current consumption of the IC. This

Latched Off Mode can only be reset if the V

VCC

< 6.23V.

In this mode, only the UVLO is working which controls

the Startup Cell by switching on/off at V

VCCon

VCCoff

During this phase, the average current consumption is

only 250µA. As there is no longer a self-supply by the

auxiliary winding, the VCC drops. The Undervoltage

Lockout switches on the integrated Startup Cell when

VCC falls below 10.5V. The Startup Cell is switched off

again when VCC has exceeded 18V. Once the Latched

Off Mode was entered, there is no Start Up Phase

whenever the VCC exceeds the switch-on level of the

Undervoltage Lockout. Therefore the VCC voltage

changes between the switch-on and switch-off levels of

the Undervoltage Lockout with a saw tooth shape (see

Figure 26).

Figure 26 Signals in Latched Off Mode

The Thermal Shutdown block monitors the junction

temperature of the IC. After detecting a junction

temperature higher than latched thermal shutdown

temperature; T

jSD

, the Latched Off Mode is entered.

The signals coming from the temperature detection and

VCC overvoltage detection are fed into a spike

blanking with a time constant of 30µs in order to ensure

the system reliability.

Furthermore, a short winding or short diode on the

secondary side can be detected by the comparator C11

which is in parallel to the propagation delay

compensated current limit comparator C10. In normal

operating mode, comparator C10 controls the

maximum level of the CS signal at 1.06V. If there is a

VCC Overvoltage Latched Off Mode

Overtemperature Latched Off Mode

Short Winding/Short Diode Latched Off Mode

BL pin < 0.25V Latched Off Mode

Overload Auto Restart Mode

Open Loop Auto Restart Mode

VCC Undervoltage Auto Restart Mode

Short Optocoupler Auto Restart Mode

25.5V

Spike

Blanking

30us

Thermal Shutdown

>130°C

Latched

Off Mode

VCC

C11

1.66V

Spike

Blanking

190ns

Voltage

Reference

Control Unit

Latched Off

Mode Reset

VCC

< 6.23V

Latch

Enable

signal

30us

Blanking

Time

0.25V

1ms

counter

UVLO

10.5V

VCCStart

0.9mA

OUT

VCC

18V

F3 PWM controller

ICE3BS03LJG

Functional Description

Version 2.0 17 6 Dec 2007

failure such as short winding or short diode, C10 is no

longer able to limit the CS signal at 1.06V. Instead the

comparator C11 detects the peak current voltage >

1.66V and enters the Latched Off Mode immediately in

order to keep the SMPS in a safe stage.

In case the pre-defined Latch Off features are not

sufficient, there is a customer defined external Latch

Enable feature. The Latch Off Mode can be triggered

by pulling down the BL pin to < 0.25V. It can simply add

a trigger signal to the base of the externally added

transistor, T

at the BL pin. To ensure this latch

function will not be mis-triggered during start up, a 1ms

delay time is implemented to blank the unstable signal.

3.7.3.2 Auto Restart Mode

Figure 27 Auto Restart Mode

In case of Overload or Open Loop, the FB exceeds

4.0V which will be observed by comparator C4. Then

the internal blanking counter starts to count. When it

reaches 20ms, the switch S1 is released. Then the

clamped voltage 0.9V at V

can increase. When there

is no external capacitor C

connected, the V

will

reach 4.0V immediately. When both the input signals at

AND gate G5 is positive, the Auto-Restart Mode will be

activated after the extra spike blanking time of 30us is

elapsed. However, when an extra blanking time is

needed, it can be achieved by adding an external

capacitor, C

. A constant current source of I

will start

to charge the capacitor C

from 0.9V to 4.0V after the

switch S1 is released. The charging time from 0.9V to

4.0V are the extendable blanking time. If C

is 0.22uF

and I

is 13uA, the extendable blanking time is around

52ms and the total blanking time is 72ms. In combining

the FB and blanking time, there is a blanking window

generated which prevents the system to enter Auto

Restart Mode due to large load jumps.

In case of VCC undervoltage, the IC enters into the

Auto Restart Mode and starts a new startup cycle.

Short Optocoupler also leads to VCC undervoltage as

there is no self supply after activating the internal

reference and bias.

In contrast to the Latched Off Mode, there is always a

Startup Phase with switching cycles in Auto Restart

Mode. After this Start Up Phase, the conditions are

again checked whether the failure mode is still present.

Normal operation is resumed once the failure mode is

removed that had caused the Auto Restart Mode.

4.0V

0.9V

Control Unit

Auto

Restart

Mode

5.0V

20ms

Blanking

Time

Spike

Blanking

30us

Version 2.0 18 6 Dec 2007

F3 PWM controller

ICE3BS03LJG

Electrical Characteristics

4 Electrical Characteristics

Note: All voltages are measured with respect to ground (Pin 8). The voltage levels are valid if other ratings are

not violated.

4.1 Absolute Maximum Ratings

Note: Absolute maximum ratings are defined as ratings, which when being exceeded may lead to destruction

of the integrated circuit. For the same reason make sure, that any capacitor that will be connected to pin 7

(VCC) is discharged before assembling the application circuit.

4.2 Operating Range

Note: Within the operating range the IC operates as described in the functional description.

Parameter Symbol Limit Values Unit Remarks

min. max.

HV Voltage V

-500V

VCC Supply Voltage V

VCC

-0.3 27 V

FB Voltage V

-0.3 5.0 V

CS Voltage V

-0.3 5.0 V

Junction Temperature T

-40 150 °C

Storage Temperature T

-55 150 °C

Thermal Resistance

Junction -Ambient

thJA

-185K/W

ESD Capability (incl. Drain Pin) V

ESD

- 2 kV Human body model

According to EIA/JESD22-A114-B (discharging a 100pF capacitor through a 1.5kΩ series resistor)

Parameter Symbol Limit Values Unit Remarks

min. max.

VCC Supply Voltage V

VCC

VCCoff

26 V

Junction Temperature of

Controller

jCon

-25 130 °C Max value limited due to thermal

shut down of controller

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P25

ICE3BS03LJGXUMA1

Mfr. #:

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Manufacturer:

Infineon Technologies

Description:

AC/DC Converters OFF-LINE SMPS CRRNT MODE CONTROLLER

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