LTC2925IUF#PBF Linear Technology, LTC2925IUF#PBF Datasheet - Page 12

• Manufacturer Part Number: LTC2925IUF#PBF
• Description: IC POWER SUPPLY CONTROLLER 24QFN
• Manufacturer: Linear Technology

Specifications of LTC2925IUF#PBF

• Applications: Power Supply Controller
• Voltage - Supply: 2.9 V ~ 5.5 V
• Current - Supply: 1.5mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-QFN
• Voltage Supervisor Type: Power Supply Tracker
• Number Of Voltage Supervisors: 4
• Operating Supply Voltage (min): 2.9V
• Operating Supply Voltage (max): 5.5V
• Operating Temperature Classification: Industrial
• Operating Temp Range: -40C to 85C
• Pin Count: 24
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Lead Free Status / Rohs Status: Compliant

LTC2925
APPLICATIONS INFORMATION
Status Output
The STATUS pin provides an indication that the supplies
are fi nished ramping up. This pin is an open-drain output
that pulls low until the GATE has been fully charged.
Since the GATE pin drives the gate of the external FET, or
the RAMP pin directly when no FET is used, the supplies
are completely ramped up when the GATE pin is fully
charged. The STATUS pin will go low again when the
GATE pin is pulled low, either because of a short-circuit
fault, a power good timeout fault, or because the ON pin
has been pulled low.
Fault Output
The FAULT pin is an open-drain output that pulls low
when the electronic circuit breaker is activated due to a
short-circuit or power good timeout fault. FAULT is reset
by pulling ON below 0.4V. The supplies will not be allowed
to ramp up again until the SCTMR, PGTMR and SDTMR
pins are below about 100mV, and the ON pin is pulled
above 1.23V.
12
R
R
V
R
TB1
TA1
IN
TA2
V
IN
10k
R
R
R
R
R
TB2
ONB
ONA
TB3
TA3
0.1μF
ON
REMOTE
STATUS
FAULT
RAMPBUF
TRACK1
TRACK2
TRACK3
V
GND
CC
SENSEP SENSEN
Figure 9. Retry on Fault
SCTMR
R
C
SENSE
SCTMR
LTC2925
SDTMR
10Ω
C
SDTMR
Retry on Fault
The LTC2925 continuously attempts to ramp up the outputs
after a fault if the FAULT pin is tied to the ON pin (Figure 9).
If a short-circuit fault occurs in this confi guration, the
SCTMR pin ramps up the C
it reaches 1.23V. Then, GATE is pulled low turning off the
shorted FET. At the same time, the FAULT pin’s open-drain
output pulls ON low. The C
with 2μA until it reaches about 100mV. After the C
capacitor reaches 100mV, the shutdown timer begins and
upon completing a shutdown timer cycle, the supplies start
ramping up again. If there is no short-circuit this time, the
supplies will come up normally. Otherwise the retry cycle
will repeat. If a longer off time is required between retry
attempts, the C
providing a greater delay before the FET’s GATE ramps up
on each cycle. Note that tying FAULT to ON also causes the
LTC2925 to retry on Power Good Timeout faults. In this
mode, verify that the slave supplies’ current limits provide
suffi cient protection under short-circuit conditions.
GATE
Q1
PGTMR
C
GATE
C
PGTMR
RAMP
SD1
SD2
SD3
PGI
FB1
FB2
FB3
MASTER
SDTMR
R
R
R
2925 F09
RST
RUN/SS
FB
RUN/SS
FB
RUN/SS
FB
FA1
FA2
FA3
MONITOR
SUPPLY
DC/DC
DC/DC
DC/DC
R
R
R
FB1
FB3
FB2
capacitor value can be increased,
V
V
V
IN
OUT
IN
OUT
IN
OUT
IN
IN
IN
SCTMR
SCTMR
SLAVE1
SLAVE2
SLAVE3
capacitor with 50μA until
capacitor is pulled down
SCTMR
2925fc