Datasheet
LTC3838
7
3838fa
TYPICAL PERFORMANCE CHARACTERISTICS
Phase Relationship:
PHASMD = Ground
Phase Relationship:
PHASMD = Float
Phase Relationship:
PHASMD = INTV
CC
Overcurrent Protection
Regular Soft Start-Up
Short-Circuit Protection
Soft Start-Up Into
Pre-Biased Output
Overvoltage Protection
Output Tracking
RUN1
5V/DIV
V
OUT
500mV/DIV
1ms/DIV
3838 G09
C
SS
= 10nF
V
IN
= 12V
V
OUT
= 1.2V
FORCED CONTINUOUS MODE
FIGURE 17 CIRCUIT, CHANNEL 1, V
RNG1
= SGND
TRACK/SS1
200mV/DIV
RUN1
5V/DIV
V
OUT
500mV/DIV
1ms/DIV
3838 G10
C
SS
= 10nF
V
IN
= 12V
V
OUT
= 1.2V
V
OUT
PRE-BIASED TO 0.75V
FIGURE 17 CIRCUIT, CHANNEL 1, V
RNG1
= SGND
TRACK/SS1
200mV/DIV
V
OUT
500mV/DIV
10ms/DIV
3838 G11
V
IN
= 12V
V
OUT
= 1.2V
FORCED CONTINUOUS MODE
FIGURE 17 CIRCUIT, CHANNEL 1, V
RNG1
= SGND
TRACK/SS1
200mV/DIV
V
OUT
100mV/DIV
AC-COUPLED
5ms/DIV
3838 G12
V
IN
= 12V
V
OUT
= 1.2V
FORCED CONTINUOUS MODE
CURRENT LIMIT = 17A
OVERLOAD = 7.5A TO 17.5A
FIGURE 17 CIRCUIT, CHANNEL 1, V
RNG1
= SGND
I
L
5A/DIV
FULL CURRENT LIMIT
WHEN V
OUT
HIGHER
THAN HALF OF REGULATED
V
OUT
1V/DIV
SHORT-
CIRCUIT
TRIGGER
500µs/DIV
3838 G13
V
IN
= 12V
V
OUT
= 1.2V
I
LOAD
= 0A
FIGURE 17 CIRCUIT, CHANNEL 1, V
RNG1
= SGND
I
L
10A/DIV
C
OUT
RECHARGE
CURRENT LIMIT STARTS TO FOLD BACK AS
V
OUT
DROPS BELOW HALF OF REGULATED
V
OUT
100mV/DIV
AC-COUPLED
20µs/DIV
3838 G14
V
IN
= 12V
V
OUT
= 1.2V
FORCED CONTINUOUS
MODE
I
LOAD
= 0A
FIGURE 17 CIRCUIT, CHANNEL 1, V
RNG1
= SGND
BG STAYS ON UNTIL
V
OUT
IS PULLED
BELOW OVERVOLTAGE
THRESHOLD
I
L
10A/DIV
BG1
5V/DIV
OVERVOLTAGE CREATED BY APPLYING
A CHARGED CAPACITOR TO V
OUT
500ns/DIV
60°
0°
3838 G15
FIGURE 19 CIRCUIT
V
IN
= 12V
V
OUT1
= 5V, V
OUT2
= 3.3V
LOAD = 0A
MODE/PLLIN = 333kHz EXTERNAL CLOCK
CLKOUT
5V/DIV
SW2
10V/DIV
SW1
10V/DIV
PLLIN
5V/DIV
180°
500ns/DIV
0°
3838 G15
FIGURE 19 CIRCUIT
V
IN
= 12V
V
OUT1
= 5V, V
OUT2
= 3.3V
LOAD = 0A
MODE/PLLIN = 333kHz EXTERNAL CLOCK
CLKOUT
5V/DIV
SW2
10V/DIV
SW1
10V/DIV
PLLIN
5V/DIV
90°
180°
500ns/DIV
0°
3838 G17
FIGURE 19 CIRCUIT
V
IN
= 12V
V
OUT1
= 5V, V
OUT2
= 3.3V
LOAD = 0A
MODE/PLLIN = 333kHz EXTERNAL CLOCK
CLKOUT
5V/DIV
SW2
10V/DIV
SW1
10V/DIV
PLLIN
5V/DIV
120°
240°