Datasheet XDPL8218 (Infineon) - 9

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XDPL8218 Digital Flyback Controller IC XDP™ Digital Power Functional description
When VFB,filtered is between VFB,ABM (0.8 V) and VFB,on (1.2 V), the
DCM
power transfer is controlled by regulating the switching period(frequency), with minimum on-time of ton,min(Vin) which is adapted based on the estimated input voltage Vin. When VFB,filtered is VFB,on (1.2 V) or more, and its corresponding minimum switching period (based on the purple curve in
Figure 4
) is higher than the system 1st valley switching period tsw,QR1 (see cyan curve in
Figure 4
as an example), the controller operates in
DCM
and the power transfer is controlled by regulating the on-time and switching period(frequency). • VGD time ton VAUX tsw,DCM 0 V time
Figure 6 Switching waveforms in DCM
•
ABM
: During
DCM
or
QRM1
, if VFB,filtered is below VFB,ABM (0.8 V) for at least a duration based on tblank,ABM parameter, the controller enters
ABM
. In
ABM
, the switching period tsw,ABM is fixed to a maximum value (50 μs) based on fsw,min (20 kHz), while the burst frequency is fixed based on fburst parameter to minimize the audible noise. The power transfer in
ABM
is controlled by regulating the pulse number and the on-time, based on VFB,filtered taken at the last pulse of previous burst cycle, as shown in
Figure 7
. If VFB,filtered exceeds VFB,ABM (0.8 V), the controller enters
DCM
or
QRM1
. VFB VFB,filtered ton = α nABM = 4 ton = β nABM = 3 ton = γ nABM = 2 wake wake wake wake sleep up up sleep up sleep up sleep 1/f t burst 1/fburst 1/fburst VGD 1/fsw,min 1/fsw,min 1/fsw,min 1/fsw,min ton = α ton = β ton = γ nABM = 4 nABM = 3 nABM = 2 t Approx. Approx. Approx. Approx. nwakeup nwakeup nwakeup nwakeup x 19 µs x 19 µs x 19 µs x 19 µs
Figure 7 Switching waveforms in ABM
When VFB,filtered is VFB,min or lower, the power transfer is minimum with ABM minimum on-time ton,min,ABM and minimum number of pulses per burst cycle nABM,min being applied. As ton,min,ABM could be too short to ensure sufficient transformer demagnetization time, the output and input voltages may not be reflected and sensed correctly via ZCD pin. Hence, the output voltage protections are not available in
ABM
and the input voltage protections can optionally be enabled using ENVin,ABM parameter. Datasheet 9 Revision 1.0 2018-06-06 Document Outline Features Product validation Potential applications Description Table of contents 1 Pin configuration 2 Functional block diagram 3 Functional description 3.1 Regulated mode 3.2 Configurable gate voltage rising slope at GD pin 3.3 Startup 3.4 Line synchronization 3.5 Input voltage and output voltage estimation 3.5.1 Output voltage estimation 3.5.2 Input voltage estimation 3.6 Power factor correction 3.7 Protection features 3.7.1 Primary MOSFET overcurrent protection 3.7.2 Output undervoltage protection 3.7.3 Output overvoltage protection 3.7.4 Transformer demagnetization time shortage protection 3.7.5 Minimum input voltage startup check and input undervoltage protection 3.7.6 Maximum input voltage startup check and input overvoltage protection 3.7.7 VCC undervoltage lockout 3.7.8 VCC undervoltage protection 3.7.9 VCC overvoltage protection 3.7.10 IC overtemperature protection 3.7.11 Other protections 3.7.12 Protection reactions 3.8 Debug mode 4 List of Parameters 5 Electrical Characteristics and Parameters 5.1 Package Characteristics 5.2 Absolute Maximum Ratings 5.3 Operating Conditions 5.4 DC Electrical Characteristics 6 Package Dimensions 7 References Revision History Glossary ABM CCM CRC CV DCM ECG EMI GUI IC LED OCP1 PC PF PFC QRM1 SSR THD UART USB UVLO Disclaimer