LTC3839 Datasheet, PDF (6/50 Pages) Linear Technology – Fast, Accurate, 2-Phase, Single-Output Step-Down DC/DC Controller

LTC3839
TYPICAL PERFORMANCE CHARACTERISTICS
Regular Soft Start-Up
RUN
5V/DIV
TRACK/SS
200mV/DIV
V_OUT
500mV/DIV
C_SS = 10nF
1ms/DIV
V_IN = 12V
V_OUT = 1.2V
FORCED CONTINUOUS MODE
Soft Start-Up Into
Pre-Biased Output
RUN
5V/DIV
V_OUT
500mV/DIV
TRACK/SS
200mV/DIV
3839 G09
C_SS = 10nF
1ms/DIV
V_IN = 12V
V_OUT = 1.2V
V_OUT PRE-BIASED TO 0.75V
Output Tracking
TRACK/SS
200mV/DIV
V_OUT
500mV/DIV
3839 G10
V_IN = 12V
10ms/DIV
V_OUT = 1.2V
FORCED CONTINUOUS MODE
3839 G11
Overcurrent Protection
I_L
5A/DIV
FULL CURRENT LIMIT
WHEN V_OUT HIGHER
THAN HALF OF REGULATED
V_OUT
100mV/DIV
AC-COUPLED
V_IN = 12V
5ms/DIV
V_OUT = 1.2V
FORCED CONTINUOUS MODE
Short-Circuit Protection
Overvoltage Protection
SHORT-
CIRCUIT
TRIGGER
I_L
10A/DIV
V_OUT
1V/DIV
I_L
10A/DIV
CURRENT LIMIT STARTS TO FOLD BACK AS
V_OUT DROPS BELOW HALF OF REGULATED
C_OUT
RECHARGE
V_OUT
100mV/DIV
AC-COUPLED
BG1
5V/DIV
OVERVOLTAGE CREATED BY APPLYING
A CHARGED CAPACITOR TO V_OUT
3839 G12
V_IN = 12V
V_OUT = 1.2V
I_LOAD = 0A
500μs/DIV
3839 G13
V_IN = 12V
20μs/DIV
3839 G14
V_OUT = 1.2V
BG STAYS ON UNTIL
FORCED CONTINUOUS V_OUT IS PULLED
MODE
BELOW OVERVOLTAGE
I_LOAD = 0A
THRESHOLD
Phase Relationship:
PHASMD = Ground
Phase Relationship:
PHASMD = Float
PLLIN
5V/DIV
SW1
10V/DIV
0°
SW2
10V/DIV
180°
CLKOUT
5V/DIV
60°
500ns/DIV
3839 G15
FIGURE 13 CIRCUIT
V_IN = 12V
LOAD = 0A
MODE/PLLIN = 333kHz EXTERNAL CLOCK
PLLIN
5V/DIV
SW1
10V/DIV
0°
SW2
10V/DIV
180°
CLKOUT
5V/DIV
90°
500ns/DIV
3839 G16
FIGURE 13 CIRCUIT
V_IN = 12V
LOAD = 0A
MODE/PLLIN = 333kHz EXTERNAL CLOCK
Phase Relationship:
PHASMD = INTV_CC
PLLIN
5V/DIV
SW1
10V/DIV
0°
SW2
10V/DIV
240°
CLKOUT
5V/DIV
120°
500ns/DIV
3839 G17
FIGURE 13 CIRCUIT
V_IN = 12V
LOAD = 0A
MODE/PLLIN = 333kHz EXTERNAL CLOCK
3839fa
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