Datasheet
LTM4611
15
4611fb
For more information www.linear.com/LTM4611
Even for applications that do not require tracking or
sequencing, a minimum recommended value for C
SS
is
10nF (X7R MLCC, 10% tolerance, nominal; X5R material
may be substituted if the capacitor temperature will not
exceed 85°C), yielding extreme turn-on rise times of 3.8ms
Figure 4. Dual Outputs (1.5V and 1.2V) With Tracking
Figure 5. Output Voltage Coincident Tracking
applicaTions inForMaTion
COMP
TRACK/SS
RUN
PLLFLTR/f
SET
MODE_PLLIN
PGOOD
V
OUT
V
OUT_LCL
DIFFV
OUT
V
OSNS
+
V
OSNS
–
V
FB
LTM4611
V
IN
R2
10k
R
FB1
69.8k
C
IN3
22µF
10V
C
P1
*
47pF
C
SS
SOFT-START
CAPACITOR
C
OUT1
*
470µF
6.3V
C
OUT2
*
100µF
6.3V
V
OUT
1.5V
15A
INTV
CC
CONTINUOUS MODE
V
IN
1.8V TO 5.5V
SGND GND
+
C
FF1
*
COMP
TRACK/SS
RUN
PLLFLTR/f
SET
MODE_PLLIN
PGOOD
V
OUT
V
OUT_LCL
DIFFV
OUT
V
OSNS
+
V
OSNS
–
V
FB
LTM4611
V
IN
R1
10k
R
FB2
121k
C
P2
*
47pF
*SEE TABLE 5
C
FF2
*
V
OUT
1.2V
15A
C
OUT3
*
470µF
6.3V
C
OUT4
*
100µF
6.3V
INTV
CC
CONTINUOUS MODE
4611 F04
SGND GND
+
R
TB
60.4k
R
TA
121k
MASTER RAMP
OR OUTPUT
V
IN
1.8V TO 5.5V
C
IN2
22µF
10V
C
IN1
22µF
10V
C
IN6
22µF
10V
C
IN5
22µF
10V
C
IN4
22µF
10V
4611 F05
TIME
SLAVE OUTPUT
MASTER OUTPUT
OUTPUT
VOLTAGE
minimum to 9.8ms maximum. Tracking a rail in a man-
ner such that TRACK/SS ramps up at a rate faster than
210V/s may also warrant special attention, as explained
in the following.
Faster turn-on and tracking rates are achievable, if needed:
one need only decrease the default PLLFLTR/f
SET
RC time
constant. Recall that the PLLFLTR/f
SET
pin is biased to
1.23V via a high impedance source (>350kΩ); also be aware
that the internal PLL filter contains an initially discharged
10nF capacitor prior to INTV
CC
being established.
Requiring the output voltage to power up rapidly without
attention to the PLLFLTR/f
SET
time-constant results in
an initial switching frequency of operation that is initially
lower than expected (~250kHz)—only during the early
stages of start-up—until the PLLFLTR/f
SET
voltage reaches
steady-state value (1.23V by default).