LTC3416 Linear Technology, LTC3416 Datasheet - Page 10

• Manufacturer Part Number: LTC3416
• Description: 4A/ 4MHz/ Monolithic Synchronous Step-Down Regulator
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LTC3416
coincidentally or ratiometrically track another output volt-
age as shown in Figure 3.
If the voltage on the TRACK pin is less than 0.8V, voltage
tracking is enabled. During voltage tracking, the output
voltage regulates to the tracking voltage through a resistor
divider network. The output voltage during tracking can be
calculated with the following equation:
Voltage tracking can be accomplished by sensing a frac-
tion of the output voltage from another regulator. This is
typically done by using a resistor divider to attenuate the
output voltage that is being tracked. Setting this attenua-
tion factor equal to the reciprocal of the gain factor
provided by the feedback resistors will force the regulator
outputs to be equal to each other during tracking. If
tracking is not desired, connect the TRACK pin to SV
10
V
OUT
V
TRACK
U
(3a) Coincident Tracking
1
(4a) Coincident Tracking Setup
R
R
2
1
U
V
TRACK
OUT2
PIN
, V
TO
TIME
TRACK
Figure 3. Two Different Modes of Output Voltage Sequencing
Figure 4. Setup for Tracking and Ratiometric Sequencing
W
R4
R3
< 0.8V
R2
R1
TO
V
PIN
FB(MASTER)
V
V
OUT2
OUT1
U
IN
.
To implement the coincident tracking shown in Figure 3a,
connect an extra resistor divider to the output of V
connect its midpoint to the TRACK pin of the LTC3416 as
shown in Figure 4. The ratio of this divider should be
selected the same as that of V
implement the ratiometric sequencing in Figure 3b, no
extra resistor divider is necessary. Simply connect the
TRACK pin to V
An alternative method of tracking is shown in Figure 5. For
the circuit of Figure 5, the following equations can be used
to determine the resistor values:
R
V
V
OUT
OUT
4
(3b) Ratiometric Sequencing
1
2
R
(4b) Ratiometric Setup
3
0 8
0 8
V
.
V
.
OUT
V
OUT
TRACK
OUT2
V
V
FB(MASTER)
PIN
TO
2
1
1
1
TIME
–
R
R
1
R
2
1
4
R2
R1
R
3416 F04
3
.
TO
V
PIN
R
FB(MASTER)
5
OUT1
3416 F03
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V
V
’s resistor divider. To
OUT2
OUT1
OUT2
and
3416f