berger.h
Member level 5
Many inverters from TI have programmable Soft start pin and a any , for example LM5176, use internal this pin for current control too.
I would like to use this pin to control the output current in CC output mode for controller without internal current control loop.
if I understand correctly
SS pin have internal connected current source (5uA at LM5176) and this current source charge capacitor connected on SS pin.
Voltage on SS pin rises from 0 to 800mV in time (for example on 47nF) 0 to 7520us.
At the same time controller include error amplifier, who compare voltage on pin FV with internal reference 800mV or/and with if voltage on SS is under 800mV with voltage on SS.
CC loop works so, compare voltage from current shunt with reference voltage on when current increase set value CC loop discharge capacitor on SS pin.
Am I right?
if so ind controller work on 200kHz (5us on clock cycle) and c on SS is 4.7nF have in Soft start mode the controller will be 752us ( 150 clock cycle) with 47nF 7520us (1500 clock cycle)
What I do not understand is how big C is right for use controller in CC mode?
I would like to use this pin to control the output current in CC output mode for controller without internal current control loop.
if I understand correctly
SS pin have internal connected current source (5uA at LM5176) and this current source charge capacitor connected on SS pin.
Voltage on SS pin rises from 0 to 800mV in time (for example on 47nF) 0 to 7520us.
At the same time controller include error amplifier, who compare voltage on pin FV with internal reference 800mV or/and with if voltage on SS is under 800mV with voltage on SS.
CC loop works so, compare voltage from current shunt with reference voltage on when current increase set value CC loop discharge capacitor on SS pin.
Am I right?
if so ind controller work on 200kHz (5us on clock cycle) and c on SS is 4.7nF have in Soft start mode the controller will be 752us ( 150 clock cycle) with 47nF 7520us (1500 clock cycle)
What I do not understand is how big C is right for use controller in CC mode?