Datasheet

LTC3828
13
3828fc
OPERATION
(Refer to Functional Diagram)
INPUT VOLTAGE (V)
0
INPUT RMS CURRENT (A)
3.0
2.5
2.0
1.5
1.0
0.5
0
10 20 30 40
3828 F03
SINGLE-PHASE
DUAL CONTROLLER
2-PHASE
DUAL CONTROLLER
V
O1
= 5V/3A
V
O2
= 3.3V/3A
Figure 3. RMS Input Current Comparison
APPLICATIONS INFORMATION
Output Voltage Tracking
The LTC3828 allows the user to program how the channel
outputs ramp up by means of the TRCKSS pins. Through
these pins, the channel outputs can be set up to either
coincidentally or ratiometrically tracking, as shown in
Figure 4.
The TRCKSS pins act as clamps on the channels’ reference
voltages. V
OUT
is referenced to the TRCKSS voltage when
the TRCKSS < 0.8V and to the internal precision reference
when TRCKSS > 0.8V.
To implement the tracking in Figure 4a, connect an extra
resistive divider to the output of the master channel and
connect its midpoint to the slave channel’s TRCKSS pin.
The ratio of this divider should be selected the same as
that of channel 2’s feedback divider (Figure 5). In this
tracking mode, the master channel’s output must be
set higher than slave channel’s output. To implement
the ratiometric tracking in Figure 4b, no extra divider is
needed; simply connect one of TRCKSS pins to the other
channel’s V
FB
pin (Figure 5).
TIME
(4a) Coincident Tracking
V
OUT1
V
OUT2
OUTPUT VOLTAGE
TIME
3828 F04
(4b) Ratiometric Tracking
V
OUT1
V
OUT2
OUTPUT VOLTAGE
Figure 4. Two Different Modes of Output Voltage Tracking