LTC2925CUF Linear Technology, LTC2925CUF Datasheet - Page 19

• Manufacturer Part Number: LTC2925CUF
• Description: IC POWER SUPPLY CONTROLLER 24QFN
• Manufacturer: Linear Technology

Specifications of LTC2925CUF

• Applications: Power Supply Controller
• Voltage - Supply: 2.9 V ~ 5.5 V
• Current - Supply: 1.5mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 24-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Input: -

APPLICATIONS INFORMATION
Load Requirements
When the supplies are ramped down quickly, either the
load or the supply itself must be capable of sinking enough
current to support the ramp rate. For example, if there
is a large output capacitance on the supply and a weak
resistive load, supplies that do not sink current will have
their falling ramp rate limited by the RC time constant of
the load and the output capacitance. Figure 19 shows the
case when the 2.5V supply does not track the 1.8V and
3.3V supplies near ground.
MASTER
SLAVE2
SLAVE1
1V/DIV
Figure 20. Power Supply Start-Ups Delayed
Figure 19. Weak Resistive Load
1ms/DIV
1ms/DIV
Start-Up Delays
Often power supplies do not start-up immediatley when
their input supplies are applied. If the LTC2925 tries to
ramp-up these power supplies as soon as the input sup-
ply is present, the start-up of the outputs may be delayed
defeating the tracking circuit (Figure 20). Often this delay
is intentionally confi gured by a soft-start capacacitor. This
can be remedied either by reducing the soft-start capacitor
on the slave supply or by increasing the shutdown timer
cycle confi gured by C
2925 F19
2925 F20
1V/DIV
SLAVE1
MASTER
SLAVE2
ON
SDTMR
.
LTC2925
19
2925fc