LTC3025

9

3025fd

APPLICATIONS INFORMATION

The LTC3025 will cycle in and out of thermal shutdown

without latch-up or damage until the overstress condition

avoided as it can degrade the performance or shorten the

life of the part.

Soft-Start Operation

The LTC3025 includes a soft-start feature to prevent

excessive current flow during start-up. When the LDO is

enabled, the soft-start circuitry gradually increases the LDO

reference voltage from 0V to 0.4V over a period of about

600μs. There is a short 700μs delay from the time the

part is enabled until the LDO output starts to rise. Figure 5

shows the start-up and shutdown output waveform.

During power-up, the output shutdown circuitry is not

the output voltage can drift up during power-up due to

input, the shutdown circuitry is active and the output is

actively held off. This usually causes no circuit problems

and is similar to 3-terminal regulators such as the LT3080,

LT1086 and LT317 which have no ground pin and can have

the output rise under some conditions. A slowly rising

With fast rising inputs (>1V/ms) or with sufficient resis-

reduced or eliminated. Such conditions also reduce or

eliminate non-monotonic initial power-up with the part

in shutdown or it is actively held on when enabled under

all conditions.

OFF

1.2V

0V

ON

SHDN

200mV/DIV

500μs/DIV

3025 F05

Figure 5. Output Start-Up and Shutdown