LTM4608 LINER [Linear Technology], LTM4608 Datasheet - Page 15

• Manufacturer Part Number: LTM4608
• Description: Low VIN, 8A DC/DC ?ModuleTM with Tracking, Margining, and Frequency Synchronization
• Manufacturer: LINER [Linear Technology]

same as the slave regulator’s feedback divider to implement
coincident tracking. The LTM4608 uses an accurate 10k
resistor internally for the top feedback resistor. Figure 5
shows an example of coincident tracking:
V
V
reference voltage. When the Master’s output is divided down
with the same resistor values used to set the slave’s output,
this resistor divider is connected to the slave’s track pin.
The slave will then coincident track with the master until it
reaches its fi nal value. The master will continue to its fi nal
value from the slave’s regulation point. Voltage tracking is
disabled when V
5 will be equal to R
APPLICATIONS INFORMATION
TRACK
TRACK
Slave = 1+
has a control range of 0V to 0.596V, or the internal
is the track ramp applied to the slave’s track pin.
R
TRACK
10k
V
FB4
5V
IN
FB2
is more than 0.596V. R
• V
for coincident tracking.
OR APPLY AN EXTERNAL TRACKING RAMP
TRACK
t = –(ln (1 – 0.596/V
C
RAMP WITH R
SR
APPLY A CONTROL
100μs SOFT-START
R
TIED TO V
FOR DISABLE
AND DEFAULT
SR
TIE TO V
MASTER
Figure 5. Dual Outputs (3.3V and 1.5V) with Tracking
3.3V
IN
IN
R
10k
R
6.65k
IN
SR
C
) • R
FB3
FB4
WHERE
SR
AND
SR
FB4
• C
RUN
RUN
TRACK
TRACK
SR
)
in Figure
V
SV
SW
RUN
PLLLPF
TRACK
MODE
PHMODE
V
SV
SW
RUN
PLLLPF
TRACK
MODE
PHMODE
CLKOUT GND
CLKOUT GND
IN
IN
IN
IN
LTM4608
LTM4608
CLKIN
CLKIN
The track pin of the master can be controlled by an external
ramp or by R
RC ramp time can be programmed using equation:
SGND
SGND
PGOOD
PGOOD
BSEL
BSEL
V
MGN
V
MGN
I
I
t = – ln 1–
THM
THM
OUT
OUT
I
I
FB
FB
TH
TH
4608 F05
3.3V
1.5V
R
6.65k
R
2.21k
SR
C2
100pF
FB2
FB1
and C
0.596V
V
IN
C1
100μF
C3
22pF
SR
100μF
in Figure 5 referenced to V
+
Figure 6
• R
TIME
MASTER
3.3V
7A
C4
100μF
POSCAP
SR
MASTER OUTPUT
• C
SLAVE OUTPUT
SLAVE
1.5V
8A
SR
LTM4608
4608 F06
15
IN
. The
4608f