Datasheet
Table Of Contents
- Figure 1. Typical topology
- Table 1. Device summary
- 1 Block diagram
- 2 Typical power
- 3 Pin settings
- 4 Electrical data
- 5 Typical electrical characteristics
- Figure 7. Current limit vs. TJ
- Figure 8. Switching frequency vs. TJ
- Figure 9. Drain start voltage vs. TJ
- Figure 10. HFB vs. TJ
- Figure 11. Brownout threshold vs. TJ
- Figure 12. Brownout hysteresis vs. TJ
- Figure 13. Brownout hysteresis current vs. TJ
- Figure 14. Operating supply current (not switching) vs. TJ
- Figure 15. Operating supply current (switching) vs. TJ
- Figure 16. Current limit vs. RLIM
- Figure 17. Power MOSFET ON resistance vs. TJ
- Figure 18. Power MOSFET breakdown voltage vs. TJ
- Figure 19. Thermal shutdown
- 6 Typical circuit
- 7 Efficiency performances for a typical flyback converter
- 8 Operation description
- 8.1 Power section and gate driver
- 8.2 High voltage startup generator
- 8.3 Power-up and soft-start
- 8.4 Power down operation
- 8.5 Auto-restart operation
- 8.6 Oscillator
- 8.7 Current mode conversion with adjustable current limit set point
- 8.8 Overvoltage protection (OVP)
- 8.9 About the CONT pin
- 8.10 Feedback and overload protection (OLP)
- 8.11 Burst mode operation at no load or very light load
- 8.12 Brownout protection
- 8.13 2nd level overcurrent protection and hiccup mode
- 9 Package mechanical data
- 10 Revision history
VIPER37 Operation description
Doc ID 022218 Rev 1 29/35
Figure 32. Burst mode timing diagram, light load management
8.12 Brownout protection
Brownout protection is a not-latched shutdown function activated when a condition of mains
undervoltage is detected.
The brownout comparator is internally referenced to V
BRth
,
Tabl e 8
, and disables the PWM if
the voltage applied at the BR pin is below this internal reference. Under this condition the
Power MOSFET is turned off. Until the brownout condition is present, the VDD voltage
continuously oscillates between the V
DDon
and the UVLO thresholds, as shown in the timing
diagram of
Figure 33
. A voltage hysteresis is present to improve the noise immunity.
The switching operation is restarted as the voltage on the pin is above the reference plus the
previously mentioned voltage hysteresis, see
Figure 5
.
The brownout comparator is provided also with a current hysteresis, I
BRhyst
. The user must
set the rectified input voltage above which the Power MOSFET starts switching after
brownout event, V
INon
, and the rectified input voltage below which the Power MOSFET is
switched off, V
INoff
. Thanks to the I
BRhyst
, see
Tabl e 8
, these two thresholds can be set
separately.
TIME
TIME
TIME
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