LTC2925
Multiple Power Supply
Tracking Controller with
Power Good Timeout
Fea T Descrip T
n
Flexible Power Supply Tracking Up and Down The LTC 2925 provides a simple solution to power supply
n
Power Supply Sequencing tracking and sequencing requirements. By selecting a few
n
Supply Stability Is Not Affected resistors, the supplies can be configured to ramp-up and
n
Controls Three Supplies Without Series FETs ramp-down together or with voltage offsets, time delays
n
Controls an Optional Fourth Supply with a or different ramp rates.
Series FET
The LTC2925 controls the outputs of three independent
n
Electronic Circuit Breaker
supplies without inserting any pass element losses. For
n
Remote Sense Switch Compensates for Voltage
systems that require a fourth supply, or when a supply
Drop Across a Series FET
does not allow direct access to its feedback resistors, one
n
Supply Shutdown Outputs
supply can be controlled with a series FET. When the FET
n
FAULT Output
is used, an internal remote sense switch compensates for
n
Adjustable Power Good Timeout
the voltage drop across the FET and current sense resistor,
n
Available in Narrow 24-Lead SSOP and Tiny 24-Lead
and an electronic circuit breaker provides protection from
QFN Packages
short-circuit conditions.
The LTC2925 also includes a power good timeout feature
a T
that turns off the supplies if an external supply monitor
n
V and V Supply Tracking
CORE I/O
fails to indicate that the supplies have entered regulation
n
Microprocessor, DSP and FPGA Supplies
within an adjustable timeout period.
n
Servers
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
n
Communication Systems Technology Corporation. All other trademarks are the property of their respective owners.
Typical a T
0.015 Si4412ADY
3.3V V
IN MASTER
0.1F
0.1F
10
SUPPLY
3.3V
MONITOR
138k 2.5V
V SENSEP SENSEN GATE RAMP
CC RST
1V/DIV
1.8V
ON
3.3V
PGI 1.5V
100k
SD1 RUN/SS IN
DC/DC
REMOTE
FB1 FB = 1.235V OUT 1.8V
V
IN
SLAVE1
10k 2925 TA02a
16.5k 10ms/DIV
35.7k
STATUS
3.3V
V
IN
LTC2925
SD2 RUN/SS IN
10k
DC/DC
FB2 FB = 0.8V OUT 2.5V
FAULT
SLAVE2
RAMPBUF
3.3V
1.65k 88.7k
41.2k 2.5V
TRACK1 1V/DIV
3.3V
1.8V
88.7k 1.5V
13k
SD3
RUN/SS IN
TRACK2
DC/DC
86.6k
41.2k
FB3 FB = 0.8V OUT 1.5V
TRACK3
SLAVE3
GND SCTMR SDTMR PGTMR
100k
86.6k
2925 TA02b
100k 10ms/DIV
0.47F 0.082F 0.82F
2925 TA01
2925fd
1
For more information www.linear.com/LTC2925
ion pplica
ions pplica
ion uresLTC2925
a Te Maxi Mu M r a T (Notes 1, 2)
Supply Voltage (V ) ................................. 0.3V to 10V GATE (Note 3) ......................................0.3V to 11.5V
CC
Input Voltages Average Current
ON, PGI, SENSEP, SENSEN ................... 0.3V to 10V TRACK1, TRACK2, TRACK3 .................................5mA
TRACK1, TRACK2, TRACK3 .........0.3V to V + 0.3V FB1, FB2, FB3.......................................................5mA
CC
SCTMR, SDTMR, PGTMR ............0.3V to V + 0.3V Operating Temperature Range
CC
Output Voltages LTC2925C ................................................ 0C to 70C
FAULT, SD1, SD2, SD3, LTC2925I .............................................40C to 85C
FB1, FB2, FB3, STATUS .......................... 0.3V to 10V Storage Temperature Range .................. 65C to 150C
RAMPBUF, REMOTE ....................0.3V to V + 0.3V Lead Temperature (Soldering, 10 sec)
CC
RAMP .............................................0.3V to V + 1V MS Package ......................................................300C
CC
p in c F T
TOP VIEW
TOP VIEW
1 SCTMR
V 24
CC
2 PGTMR
SENSEP 23
24 23 22 21 20 19
3 PGI
SENSEN 22
ON
1 18 STATUS
4 STATUS
ON 21
SDTMR 2 17 FAULT
5 FAULT
SDTMR 20
SD1 3 16 GATE
6 GATE 25
SD1 19
SD2 4 15 RAMP
7 RAMP
SD2 18
SD3 5 14 REMOTE
8 REMOTE
SD3 17
RAMPBUF
6 13 FB1
9 FB1
RAMPBUF 16
7 8 9 10 11 12
10 TRACK1
GND 15
11 TRACK2
FB3 14
12 FB2
TRACK3 13
UF PACKAGE
24-LEAD (4mm 4mm) PLASTIC QFN
GN PACKAGE
EXPOSED PAD (PIN 25)
24-LEAD PLASTIC SSOP
PCB GND CONNECTION OPTIONAL
T = 125C, = 85C/W
JMAX JA
T = 125C, = 37C/W
JMAX JA
Der in F Ma T