CM6900G Datasheet, PDF (10/12 Pages) Champion Microelectronic Corp. – Resonant Controller

CM6900G
Resonant Controller
Soft Start and Enable
Soft start of the FM and PWM is controlled by the selection of the external capacitor at CSS pin. A current source
of 8uA supplies the charging current for the capacitor. Soft start of the FM and PWM begins at 1.25V. The soft start
pin CSS also serves as an enable function. The output drivers are enabled when CSS pin reached 1V.
Auto-retry Mode
During normal operation, CSS pin will be charged to 5.5V + VBE. When VFB exceeds 2.93V due to OVP or ILIM
exceeds 1V due to over current condition, output drivers are immediate set to low , and CSS begins to discharge
with 3.3uA current source. When CSS pin is below 0.9V, 8uA current source start charging the CSS pin. When
CSS pin reaches 1V, the output drivers are re-enable and the controller goes into soft start mode. If OVP or over
current condition still exists then, the outputs are immediately disabled, but CSS continues to charge toward 5V.
When CSS reaches 5V, 8uA charging current is disabled and 3.3uA current source begins to discharge the CSS,
and the cycle repeat until OVP or over current condition is removed.
2007/11/22 Rev1.0
Champion Microelectronic Corporation
Page 10