LTC3780EG Linear Technology, LTC3780EG Datasheet - Page 15

• Manufacturer Part Number: LTC3780EG
• Description: IC,SMPS CONTROLLER,CURRENT-MODE,CMOS,SSOP,24PIN,PLASTIC
• Manufacturer: Linear Technology

OPERATIO
OUTPUT OVERVOLTAGE PROTECTION
An overvoltage comparator guards against transient over-
shoots (>7.5%) as well as other more serious conditions
that may overvoltage the output. In this case, Synchro-
nous Switch B and Synchronous Switch D are turned on
until the overvoltage condition is cleared or the maximum
negative current limit is reached. When inductor current is
lower than the maximum negative current limit, Synchro-
nous Switch B and Synchronous Switch D are turned off,
and Switch A and Switch C are turned on until the inductor
current reaches another negative current limit. If the
comparator still detects an overvoltage condition, Switch
A and Switch C are turned off, and Synchronous Switch B
and Synchronous Switch D are turned on again.
SHORT-CIRCUIT PROTECTION AND CURRENT LIMIT
Switch A on-time is limited by output voltage. When
output voltage is reduced and is lower than its nominal
level, Switch A on-time will be reduced.
U
In every Boost mode cycle, current is limited by a voltage
reference, which is proportional to the I
maximum sensed current is limited to 160mV. In every
Buck mode cycle, the maximum sensed current is limited
to 130mV.
STANDBY MODE PIN
The STBYMD pin is a three-state input that controls
circuitry within the IC as follows: When the STBYMD pin
is held at ground, the SS pin is pulled to ground. When the
pin is left open, the internal SS current source charges the
SS capacitor, allowing turn-on of the controller and acti-
vating necessary internal biasing. When the STBYMD pin
is taken above 2V, the internal linear regulator is turned on
independent of the state on the RUN and SS pins, provid-
ing an output power source for “wake-up” circuitry.
Decouple the pin with a small capacitor (0.1µF) to ground
if the pin is not connected to a DC potential.
TH
LTC3780
pin voltage. The
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