LTC2925CUF Linear Technology, LTC2925CUF Datasheet - Page 16

• 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: -

LTC2925
APPLICATIONS INFORMATION
Offset Tracking Example
Converting the circuit in the coincident tracking example
to the offset tracking shown in Figure 15 is relatively
simple. Here the 1.8V slave 1 supply ramps up 1V below
the master. The ramp rate remains the same (100V/s), so
there are no changes necessary to steps 1 and 2 of the
3-step design procedure. Only step 3 must be considered.
Be sure to verify that the chosen voltage offsets will allow
the slave supplies to ramp up completely. In this example,
if the voltage offset were 2V, the slave supply would only
ramp up to 3.3V – 2V = 1.3V.
3. Choose R
First, convert the desired voltage offset, V
t
From Equation 4:
From Equation 5:
16
D
, using the ramp rate:
R
R
t
D
TA
TA
=
″ =
=
V
S
OS
13 1
S
1
0 8
TA
ms
. ||
=
.
k
to obtain the desired delay.
100
V
•
•
100
13 2
1
16 5
V
V s
.
/
.
V s
k
1V/DIV
/
k
=
≈
10
=
6 65
.
13 2
ms
.
k
k
10ms/DIV
Figure 15. Offset Tracking from Figure 16
OS
, to a delay,
( )
6
MASTER
SLAVE2
SLAVE1
SLAVE3
3.3V V
R
16.5k
R
6.65k
31.6k
TB1
TA1
R
IN
TA2
V
V
IN
IN
10k
10k
R
88.7k
R
138k
R
100k
86.6k
31.6k
R
R
TB2
ONB
ONA
TB3
TA3
0.1μF
10ms/DIV
ON
REMOTE
STATUS
FAULT
RAMPBUF
TRACK1
TRACK2
TRACK3
V
GND
Figure 16. Offset Tracking Example
CC
SENSEP SENSEN
SCTMR
0.015Ω
C
0.41μF
SCTMR
LTC2925
SDTMR
10Ω
Si4412ADY
C
0.082μF
2925 F15
GATE
SDTMR
Q1
1V/DIV
C
0.1μF
GATE
PGTMR
C
0.82μF
RAMP
PGTMR
SD1
SD2
SD3
PGI
FB1
FB2
FB3
MASTER
R
35.7k
R
41.2k
R
100k
2925 F16
RST
RUN/SS
FB = 1.235V
RUN/SS
FB = 0.8V
RUN/SS
FB = 0.8V
FA1
FA2
FA3
MONITOR
SUPPLY
DC/DC
DC/DC
DC/DC
16.5k
86.6k
R
88.7k
R
R
FB1
FB3
FB2
3.3V
OUT
3.3V
OUT
3.3V
OUT
IN
IN
IN
2925fc
1.8V
SLAVE1
2.5V
SLAVE2
1.5V
SLAVE3