Datasheet

L6730 - L6730B Device description
Doc ID 11938 Rev 3 17/52
5.5 Error amplifier
5.6 Soft-start
When both V
CC
and V
IN
are above their turn-on thresholds (V
IN
is monitored by the OCH
pin) the start-up phase takes place. Otherwise the SS pin is internally shorted to GND. At
start-up, a ramp is generated charging the external capacitor C
SS
with an internal current
generator. The initial value for this current is 35 µA and charges the capacitor up to 0.5 V.
After that it becomes 10 µA until the final charge value of approximately 4 V (see Figure 5).
Figure 7. Error amplifier reference
2.5
V
100K
EAREF
V
CC
DR
0.6
V
1.2
V
EXT
Error Amplifier Ref.
Figure 8. Device start-up: voltage at the SS pin
t
t
0.5V
4V
V
cc
V
in
V
ss
4.2V
1.25V
4.2V or 8.6V
0.5V
Vcc
Vin
0.5V
1.25V
Vss
4V