Datasheet
Table Of Contents
- Figure 1. STEVAL- ISA115V1 demonstration board
- 1 Adapter features
- 2 Circuit description
- 3 Bill of material
- 4 Layout
- 5 Testing the board
- 6 Functional check
- 7 Feedback loop calculation guidelines
- 8 Thermal measurements
- Figure 32. Thermal measurement @ VIN = 80 VAC, full load (130 mA) Rbl = 8.2 kohm
- Figure 33. Thermal measurement @ VIN = 115 VAC, full load (130 mA) Rbl = 8.2 kohm
- Figure 34. Thermal measurement @ VIN = 230 VAC, full load (130 mA) Rbl = 8.2 kohm
- Figure 35. Thermal measurement @ VIN = 265 VAC, full load (130 mA) Rbl = 8.2 kohm
- 9 EMI measurements
- Appendix A Test equipment and measurement of efficiency and light load performance
- 10 References
- Revision history
Testing the board AN4260
10/29 DocID024275 Rev 2
5.3 Burst mode and output voltage ripple
When the converter is lightly loaded, the COMP pin voltage decreases. As it reaches the
shutdown threshold, V
COMPL
(1.1 V, typical), the switching is disabled and no more energy
is transferred to the secondary side. So, the output voltage decreases and the regulation
loop makes the COMP pin voltage increase again. As it rises 40 mV above the V
COMPL
threshold, the normal switching operation is resumed. This results in a controlled on/off
operation (referred to as "burst mode”) as long as the output power is so low that it requires
a turn-on time lower than the minimum turn-on time of the VIPER06XS. This mode of
operation keeps the frequency-related losses low when the load is very light or
disconnected, making it easier to comply with energy saving regulations.
The figures below show the output voltage ripple when the converter is no/lightly loaded and
supplied with 115 V
AC
and with 230 V
AC
respectively.
5.4 Efficiency
The active mode efficiency is defined as the average of the efficiencies measured at 25%,
50%, 75% and 100% of maximum load, at nominal input voltage (V
IN
= 115 V
AC
and V
IN
=
230 V
AC
).
External power supplies (the power supplies which are contained in a separate housing
from the end-use devices they are powering) need to comply with the Code of Conduct,
version 4 "Active Mode Efficiency" criterion, which states an active mode efficiency higher
than 65.9% for a power throughput of 1.8 W.
Another standard to be applied to external power supplies in the coming years is the DOE
(department of energy) recommendation, whose active mode efficiency requirement for the
same power throughput is 70.9%.
The presented demonstration board is compliant with both standards, as per Figure 15,
where the average efficiencies of the board at 115 V
AC
(79.2%) and at 230 V
AC
(76.4%) are
plotted with dotted lines, together with the above limits. In the same figure the efficiency at
25%, 50%, 75% and 100% of load for both input voltages is also shown.
Figure 13. Output voltage ripple at 115 V
AC
, no
load
Figure 14. Output voltage ripple at 230 V
AC
, no
load
AM16640v1
AM16641v1