lt3579iufd-trpbf Linear Technology Corporation, lt3579iufd-trpbf Datasheet - Page 12

• Manufacturer Part Number: lt3579iufd-trpbf
• Description: Lt3579/lt3579-1 6a Boost/inverting Dc/dc Converter With Fault Protection Features
• Manufacturer: Linear Technology Corporation

LT3579/LT3579-1
OPERATION
When a fault is detected, in addition to the FAULT pin
being pulled low internally, the LT3579 also disables
its CLKOUT pin, turns off its power switches, and the
GATE pin becomes high impedance (refer to the State
Diagram). The external PMOS, M1, turns off when the
gate of M1 is pulled up to its source by the external
R
PMOS turned off, the power path from V
cut off, protecting power components downstream.
At the same time, a timeout sequence commences where
the SS pin is charged up to 1.8V (the SS pin will continue
charging up to ~2.1V and be held there in the case of
a FAULT1 event still existing), and then discharged to
50mV. This timeout period relieves the part, the PMOS,
and other downstream power components from electrical
and thermal stress for a minimum amount of time as set
by the voltage ramp rate on the SS pin.
In the absence of faults, the FAULT pin is pulled high by
the external R
and 5 show the events that accompany the detection of
an output short on the LT3579.
12
GATE
resistor (see Block Diagram) With the external
FAULT
resistor (typically 100k). Figures 4
IN
to V
OUT
is
Figure 5. Continuous Output Short Showing FAULT Timeout Cycle
Figure 4. Output Short Circuit Protection of the LT3579
CLKOUT
10V/DIV
2V/DIV
5A/DIV
5V/DIV
2V/DIV
5V/DIV
5A/DIV
5V/DIV
FAULT
FAULT
GATE
V
OUT
SS
IL
IL
50ms/DIV
10μs/DIV
35791 F04
35791 F05
35791f