CM6901
SLS (SRC/LLC+SR) Controller with 1 FM+2 PWMs
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 7.5uA 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 ILIM exceeds
1V due to over current condition, output drivers are immediate set to low , and CSS begins to discharge with 0.75uA
current source. When CSS pin is below 0.9V, 7.5uA 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 over current condition
still exists then, the outputs are immediately disabled, but CSS continues to charge toward 5V. When CSS
reaches 5V, 7.5uA charging current is disabled and 0.75uA current source begins to discharge the CSS, and the
cycle repeat until over current condition is removed.
OCP Setting
5.5 V+VBE
5V
Css
0.9V
1V
ILimit
2009/11/02 Rev1.4
Champion Microelectronic Corporation
Page 12
CHAMP [ CHAMPION MICROELECTRONIC CORP. ]
