ltm4616 Linear Technology Corporation, ltm4616 Datasheet - Page 15

• Manufacturer Part Number: ltm4616
• Description: Dual 8a Per Channel Low Vin Dc/dc ?module
• Manufacturer: Linear Technology Corporation

rate is directly equal to the master’s output slew rate in
Volts/Time:
where MR is the master’s output slew rate and SR is the
slave’s output slew rate in Volts/Time. When coincident
tracking is desired, then MR and SR are equal, thus R
is equal to 10k. R
where V
tor and V
top feedback resistor of the slave regulator in equal slew
rate or coincident tracking, then R
V
Figure 5. Figure 6 shows the output voltage for coincident
tracking.
APPLICATIONS INFORMATION
FB
R
MR
SR
= V
TA
• 10k = R
=
TRACK
FB
TRACK
10k
is the feedback voltage reference of the regula-
V
FB
. Therefore R
+
is 0.596V. Since R
TB
0.596V
R
TA
V
FB
FB
RSR
MASTER
is derived from equation:
3.3V
V
–
IN
R
10k
R
6.65k
4V TO 5.5V
V
CSR
TB
TA
TRACK
R
TB
TB
10μF
10μF
= 10k and R
RUN
RUN
TA
TB
Figure 5. Dual Outputs (3.3V and 1.5V) with Tracking
FOR TRACK1:
1. TIE TO VIN TO DISABLE TRACK WITH DEFAULT 100μs SOFT START
2. APPLY A CONTROL RAMP WITH RSR AND CSR TIED TO V
3. APPLY AN EXTERNAL TRACKING RAMP DIRECTLY
V
SV
RUN1
PLLLPF1
MODE1
PHMODE1
TRACK1
V
SV
RUN2
PLLLPF2
MODE2
PHMODE2
TRACK2
is equal to R
is equal to the 10k
IN1
IN2
IN1
IN2
SW1
SW2
TA
= 6.65k in
CLKIN1
CLKIN1
SGND1
TB
with
CLKOUT1 CLKIN2
TB
LTM4616
GND1
In ratiometric tracking, a different slew rate maybe desired
for the slave regulator. R
slower than MR. Make sure that the slave supply slew rate
is chosen to be fast enough so that the slave output voltage
will reach it fi nal value before the master output.
For example: MR = 3.3V/ms and SR = 1.5V/ms. Then
R
SGND2
TB
= 22.1k. Solve for R
CLKOUT2
GND2
Figure 6. Output Voltage Coincident Tracking
IN
PGOOD1
PGOOD2
WITH t = –(ln(1–0.596/V
ITHM1
ITHM2
BSEL1
BSEL2
V
MGN1
V
MGN2
4616 F05
OUT1
ITH1
OUT2
ITH2
FB1
FB2
PGOOD
BSEL
TA
TB
R
2.21k
R
6.65k
FB1
FB2
TIME
to equal to 4.87k.
can be solved for when SR is
IN
MASTER OUTPUT
) • RSR • CSR))
SLAVE OUTPUT
100μF
100μF
LTM4616
4616 F06
100μF
MASTER
3.3V/7A
SLAVE
1.5V/8A
15
4616f