iW248

Smart IGBT Driver and Controller

Solution for Inductive Heating Control

Rev. 1.2

Datasheet

© 2020 Dialog Semiconductor

www.dialog-semiconductor.com

13 of 18

10-Dec-2020

9.4.3 Input Surge Current

If the input current is greater than 40A (programmable via digital bus from 20A to 57.5A) for more than 10ms (program-

mable between 6ms to 21ms), the output switching pulse is disabled. The circuit waits for 3 seconds and goes back to

the input voltage detection state.

9.4.4 Input Current Transient

The absolute value of the input current on each AC cycle is monitored and compared to the current in the previous

cycle. If the absolute value of the input current exceeds the absolute value of the current from the previous cycle by 2A

This can also be programmed to reduce the output power to the minimum level and stay there for 3 seconds after the

fault is removed. The minimum power will be the power target/skip power target.

9.4.5 Input Voltage Transient

Similar to the Input Current Transient protection, the RMS voltage is measured and compared to the previous AC

cycle. If the voltage changes by more than 20V default (programmable from 8V to 68V), the controller changes the

output power to the minimum value and stays at minimum power for 3 seconds after the fault is removed. The mini-

mum power will be the power target/skip power target.

9.4.6 Input Over and Under Voltage

If the input voltage exceeds an internal high voltage threshold of 285V (programmable) for more than 8 consecutive

AC cycles, the switching is disabled until the input voltage drops to a normal operating voltage range. At this point, the

controller restarts the start-up sequence.

If the input voltage drops below an internal low voltage threshold of 125V (programmable) for more than 8 AC cycles

(number of cycles is also programmable to 2/4/8/15), switching is disabled until the input voltage returns to a normal

operating voltage range. At this point, the controller goes back to input voltage detection state.

9.4.7 Input Surge Voltage Protection

If the input voltage exceeds 600V the output is immediately disabled and the circuit is shut down until fault removal

and stays off for 3 seconds after fault removal. After the 3 seconds period times out, the controller goes back to input

voltage detection state.

9.4.8 Switching Frequency Protection

The iW248 modulates the on-time to control the output power, but it also monitors on-time to protect the IGBT from

failure. If the switching frequency goes below a minimum switching frequency the device will automatically reduce the

on-time by 1ms. If the frequency stays below the minimum switching frequency for more than 8 AC cycles, the system

will be restarted by a software and POR reset.

If the 1ms reduction to the on-time is enough to bring the switching frequency above the 16kHz minimum, the on-time

will keep this adjusted value until the switching frequency goes above the minimum switching frequency plus some

hysteresis calculated by equation 9.1.

=

SW_OK

F

−

1

SW_MIN

F

2µs

1

(

)

(9.1)

The iW248 also includes maximum switching frequency protection. Once the switching frequency exceeds the maximum

value, the iW248 counts and stores the number of cycles when the switching frequency is above the maximum value. If

the value goes 10kHz above the maximum switching frequency for 8 AC cycles, the system will reset.