LTC3828 datasheet(13/32 Pages) LINER

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LTC3828

3828f

(Refer to Functional Diagram)

OPERATIO

TIME

(4a) Coincident Tracking

VOUT1

VOUT2

TIME

3828 F04

(4b) Ratiometric Tracking

VOUT1

VOUT2

Figure 4. Two Different Modes of Output Voltage Tracking

APPLICATIO S I FOR ATIO

INPUT VOLTAGE (V)

3.0

2.5

2.0

1.5

1.0

0.5

3828 F03

SINGLE PHASE

DUAL CONTROLLER

2-PHASE

DUAL CONTROLLER

VO1 = 5V/3A

VO2 = 3.3V/3A

Figure 3. RMS Input Current Comparison

Output Voltage Tracking

The LTC3828 allows the user to program how the channel

outputs ramp up and down 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’ refer-

ence voltages. VOUT 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 ratiomet-

ric tracking in Figure 4b, no extra divider is needed; simply

connect one of TRCKSS pins to the other channel’s VFB pin

(Figure 5).

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