Datasheet XDPS21071 (Infineon) - 10

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Forced Frequency Resonant Flyback controller Functional Description
MFIO

C5 burst-on VMFIOBMWK
BM 2-point Power BM Ctrl Regulation Management
C6 burst-off V

MFIOBMPA
Figure 6 Burst mode control
For the system dimensioning, it should be ensured that the voltage VVCC should be always well above the threshold V

VCCoff, including the burst-off phase. Figure 7 shows a typical burst mode operation signal for VCC and correlated current consumption.

V

VCC(t) burst-on phase

VVCCSS VVCCoff = 7.2 V

t V burst-off phase MFIO(t) VMFIOBMWK = 1.6 V VMFIOBMPA t VGD0(t) t IVCC(t) IVCCop IVCCquBM2 = 460 µA t
Figure 7 Burst operation 4.1.5 Bang-bang mode during latched and auto-restart operation
The bang-bang mode supports an IC operation without external VCC supply during the latched and auto-restart operation. It directly controls the HV startup cell depending on the set bang-bang mode turn-on threshold VVCCBBon of the corresponding auto-restart and latch mode (see Figure 8). In latch mode, the HV startup cell switch-on threshold is set to VVCCBBon = 9 V (see Chapter 4.1.5.1 and Chapter 4.1.5.2). In auto-restart mode, there is also an additional stand-by timer active that switches on the HV startup cell in a fixed time period of 500ms scheme to keep the VCC all the time at a high level above the brown-in threshold VVCCBI = 9.1 V. Then a restart can take place without going through an additional VCC brown-in cycle. Due to the low current consumption during the auto-restart break time, the startup cell is always turned on by the 500 ms timer.
Protection Modes
HV
HV Startup-cell Auto Restart
Closed/Open
Bang-Bang Ctrl Startup-Cell Mode
VVCCBBoff = 20.5 V
Driver
V
Latch
VCCBBonAR/LM = 9 V
Mode
D1
Power
VCC
Management Figure 8 Bang-bang mode control of HV startup-cell
Data Sheet 10 Revision 2.0 2019-10-30