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| LTC3828_15 Datasheet, PDF (7/32 Pages) Linear Technology – Dual, 2-Phase Step-Down Controller with Tracking | |||
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LTC3828
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise noted.
Load Step: Burst Mode Operation
(Figure 14)
Load Step: Continuous Mode
(Figure 14)
Input Source/Capacitor
Instantaneous Current
(Figure 14)
VOUT1
100mV/DIV
VOUT2
100mV/DIV
IL1
2A/DIV
VIN = 12V
50μs/DIV
VOUT1 = 5V
VOUT2 = 3.3V
LOAD STEP = 0A TO 3A
WITH RATIOMETRIC TRACKING
VOUT1
100mV/DIV
VOUT2
100mV/DIV
IL1
2A/DIV
3828 G22
VIN = 12V
50μs/DIV
VOUT1 = 5V
VOUT2 = 3.3V
LOAD STEP = 0A TO 3A
WITH RATIOMETRIC TRACKING
SW1
20V/DIV
SW2
20V/DIV
3828 G23
IIN
25A/DIV
VIN
RIPPLE
50mV/DIV
VIN = 12V
500ns/DIV
VOUT1 = 5V
VOUT2 = 3.3V
IOUT5 = IOUT3.3 = 2A
3828 G24
Burst Mode Operation
(Figure 14)
Constant Frequency (Burst
Inhibit) Operation (Figure 14)
VOUT
20mV/DIV
VOUT
20mV/DIV
IL
1A/DIV
VIN = 12V
VOUT = 5V
VFCB = OPEN
IOUT = 20mA
100μs/DIV
3828 G25
IL
0.5A/DIV
VIN = 12V
VOUT = 5V
VFCB = 5V
IOUT = 20mA
2μs/DIV
3828 G26
PIN FUNCTIONS (SSOP/QFN)
ITH1, ITH2 (Pins 2, 13/Pins 30, 12): Error Ampliï¬er Output
and Switching Regulator Compensation Point. Each as-
sociated channelsâ current comparator trip point increases
with this control voltage.
PHSMD (Pin 4, QFN Only): Control input to phase selector
which determines the phase relationship between control-
ler 1, controller 2 and the clockout signal.
VOSENSE1, VOSENSE2 (Pins 5, 14/Pins 1, 13): Error Ampliï¬er
Feedback Input. Receives the remotely-sensed feedback
voltage for each controller from an external resistive divider
across the output.
PLLFLTR (Pin 6/Pin 2): Filter Connection for Phase-Locked
Loop. Alternatively, this pin can be driven with an AC or
DC voltage source to vary the frequency of the internal
oscillator.
FCB/PLLIN (Pin 8/Pin 5): Forced Continuous Control Input
and External Synchronization Input to Phase Detector. Pull-
ing this pin below 0.8V will force continuous synchronous
operation. Feeding an external clock signal will synchronize
the LTC3828 to the external clock.
3828fc
7
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