LTC2925 Datasheet, PDF (1/20 Pages) Linear Technology – Multiple Power Supply Tracking Controller with Power Good Timeout

FEATURES
s _{Flexible Power Supply Tracking Up and Down}
s _{Power Supply Sequencing}
s _{Supply Stability Is Not Affected}
s _{Controls Three Supplies Without Series FETs}
s _{Controls an Optional Fourth Supply With a}
Series FET
s _{Electronic Circuit Breaker}
s _{Remote Sense Switch Compensates for Voltage}
Drop Across a Series FET
s _{Supply Shutdown Outputs}
s _{FAULT Output}
s _{Adjustable Power Good Timeout}
s _{Available in Narrow 24-Lead SSOP and Tiny 24-Lead}
QFN Packages _U
APPLICATIO S
s _{VCORE and VI/O Supply Tracking}
s _{Microprocessor, DSP and FPGA Supplies}
s _Servers
s _{Communication Systems}
LTC2925
Multiple Power Supply
Tracking Controller with
Power Good Timeout
DESCRIPTIO
The LTC^®2925 provides a simple solution to power supply
tracking and sequencing requirements. By selecting a few
resistors, the supplies can be configured to ramp-up and
ramp-down together or with voltage offsets, time delays
or different ramp rates.
The LTC2925 controls the outputs of three independent
supplies without inserting any pass element losses. For
systems that require a fourth supply, or when a supply
does not allow direct access to its feedback resistors, one
supply can be controlled with a series FET. When the FET
is used, an internal remote sense switch compensates for
the voltage drop across the FET and current sense resistor,
and an electronic circuit breaker provides protection from
short-circuit conditions.
The LTC2925 also includes a power good timeout feature
that turns off the supplies if an external supply monitor
fails to indicate that the supplies have entered regulation
within an adjustable time-out period.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO S
3.3V V_IN
0.1µF
0.015Ω Si4412ADY
10Ω
0.1µF
154k
100k
V_IN
V_CC SENSEP SENSEN GATE
ON
REMOTE
RAMP
PGI
SD1
FB1
MASTER
SUPPLY
MONITOR
RST
3.3V
RUN/SS IN
DC/DC
FB = 1.235V OUT
10k
V_IN
10k
1.65k
13k ^88.7k
41.2k ^86.6k
100k
STATUS
LTC2925
SD2
FAULT
FB2
RAMPBUF
TRACK1
TRACK2
SD3
TRACK3
GND SCTMR
SDTMR
FB3
PGTMR
0.47µF
0.082µF
0.82µF
35.7k ^16.5k
3.3V
RUN/SS IN
DC/DC
FB = 0.8V OUT
41.2k ^88.7k
3.3V
RUN/SS IN
DC/DC
FB = 0.8V OUT
86.6k
100k
2925 TA01
1.8V
SLAVE1
2.5V
SLAVE2
1.5V
SLAVE3
1V/DIV
3.3V
2.5V
1.8V
1.5V
3.3V
2.5V
1.8V
1.5V
10ms/DIV
2925 TA02a
1V/DIV
10ms/DIV
2925 TA02b
2925f
1