LTC2927ITS8#TRM Linear Technology, LTC2927ITS8#TRM Datasheet - Page 11

• Manufacturer Part Number: LTC2927ITS8#TRM
• Description: IC POWER SUPPLY CTRLR TSOT23-8
• Manufacturer: Linear Technology

Specifications of LTC2927ITS8#TRM

• Applications: Power Supply Controller
• Voltage - Supply: 2.9 V ~ 5.5 V
• Current - Supply: 560µA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-8, TSOT-8
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Input: -
• Other names: LTC2927ITS8

APPLICATIO S I FOR ATIO
Offset Tracking Example
Converting the circuit in the coincident tracking example
to the offset tracking shown in Figure 13 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 offset will allow
the slave supply to ramp up completely. In this example,
if the voltage offset were 2V, the slave supply would only
ramp to 3.3V – 2V = 1.3V.
3. Choose R
First, convert the desired voltage offset, V
t
From Equation 4:
From Equation 5:
R
R
t
D
D
TA
TA
, using the ramp rate:
=
″ =
=
V
S
13 1
OS
S
10
0 8
TA
.
.
1V/DIV
=
ms
k
to obtain desired delay.
V
Ω
100
•
•
13 2
16 5
1
100
U
V
V s
.
.
/
k
V s
k
Ω
Ω
/
U
=
≈
=
10
6 65
13 2
.
ms
.
k
10ms/DIV
k
Ω
W
Ω
Figure 13. Offset Tracking (from Figure 14)
OS
, to a delay
U
( )
6
MASTER
SLAVE2
SLAVE1
EARLY V
EARLY
3.3V
3.3V
IN
R
R
16.5k
6.65k
138k
100k
R
R
887k
316k
R
R
ONB
ONA
TB1
TA1
TB2
TA2
Figure 14. Offset Tracking Example
ON
RAMPBUF
TRACK
ON
RAMPBUF
TRACK
10ms/DIV
LTC2927
LTC2927
GND
GND
V
V
CC
CC
RAMP
RAMP
SDO
SDO
2927 F14
FB
FB
R
35.7k
R
412k
FA1
FA2
0.1μF
0.1μF
0.1μF
RUN/SS
FB = 1.235V
RUN/SS
FB = 0.8V
2927 F13
LTC2927
DC/DC
DC/DC
16.5k
887k
3.3V
R
3.3V
R
1V/DIV
IN
IN
FB1
FB2
OUT
OUT
MASTER
3.3V
11
SLAVE1
1.8V
SLAVE2
2.5V
2927fb