LTM4630_15 Datasheet, PDF (16/34 Pages) Linear Technology – Dual 18A or Single 36A DC/DC Module Regulator

LTM4630
APPLICATIONS INFORMATION
4V TO 15V INTERMEDIATE BUS
C4
22µF
25V
R1*
10k
C3
22µF
25V
C2
22µF
25V
C1
22µF
25V
R6
100k
D1*
5.1V ZENER
MASTER
C_SS
0.1µF
R_TB
60.4k
1.5V
R_TA
60.4k
R4
121k
RAMP TIME
t_SOFTSTART = (C_SS/1.3µA) • 0.6
* PULL-UP RESISTOR AND ZENER ARE OPTIONAL.
C10
4.7µF
INTV_CC
R2
10k
PGOOD
MODE_PLLIN
V_IN
TEMP
RUN1
RUN2
TRACK1
TRACK2
f_SET
PHASMD
CLKOUT INTV_CC EXTV_CC
LTM4630
PGOOD1
V_OUT1
V_OUTS1
SW1
V_FB1
V_FB2
COMP1
COMP2
V_OUTS2
V_OUT2
SW2
SLAVE
PGOOD
PGOOD2
C6
100µF
6.3V
1.5V AT 18A
C8
470µF
6.3V
R_FB
60.4k
40.2k
1.2V AT 18A
C5
100µF
6.3V
C7
470µF
6.3V
SGND GND DIFFP
DIFFN DIFFOUT
INTV_CC
R9
10k
4630 F06
Figure 6. Example of Output Tracking Application Circuit
MASTER OUTPUT
SLAVE OUTPUT
Regardless of the mode selected by the MODE_PLLIN pin,
the regulator channels will always start in pulse-skipping
mode up to TRACK = 0.5V. Between TRACK = 0.5V and
0.54V, it will operate in forced continuous mode and revert
to the selected mode once TRACK > 0.54V. In order to track
with another channel once in steady state operation, the
LTM4630 is forced into continuous mode operation as
soon as V_FB is below 0.54V regardless of the setting on
the MODE_PLLIN pin.
TIME
4630 F07
Figure 7. Output Coincident Tracking Waveform
to INTV_CC. After the 0.6V ramp, the TRACK pin will no
longer be in control, and the internal voltage reference
will control output regulation from the feedback divider.
Foldback current limit is disabled during this sequence
of turn-on during tracking or soft-starting. The TRACK
pins are pulled low when the RUN pin is below 1.2V. The
total soft-start time can be calculated as:
Ratiometric tracking can be achieved by a few simple
calculations and the slew rate value applied to the master’s
TRACK pin. As mentioned above, the TRACK pin has a
control range from 0 to 0.6V. The master’s TRACK pin
slew rate is directly equal to the master’s output slew rate
in Volts/Time. The equation:
MR
SR
•
60.4k
=
R_TB
where MR is the master’s output slew rate and SR is the
slave’s output slew rate in Volts/Time. When coincident
t_SOFT-START
=


C_SS
1.3µA


•
0.6
4630fa
16
For more information www.linear.com/LTM4630