DC1245A Linear Technology, DC1245A Datasheet - Page 15

• Manufacturer Part Number: DC1245A
• Description: BOARD DEMO LTM4616
• Manufacturer: Linear Technology
• Series: µModuler

Specifications of DC1245A

• Design Resources: LTM4616 Spice Model LTM4616 Gerber Files DC1245 Design Files
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 2, Non-Isolated
• Power - Output: -
• Voltage - Output: 1.2V, 1.8V
• Current - Output: 8A, 8A
• Voltage - Input: 2.7 ~ 5.5 V
• Regulator Topology: Buck
• Frequency - Switching: 1.5MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LTM4616
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Output Voltage Tracking
Output voltage tracking can be programmed externally
using the TRACK pin. The output can be tracked up and
down with another regulator. The master regulator’s output
is divided down with an external resistor divider that is the
same as the slave regulator’s feedback divider to implement
coincident tracking. The LTM4616 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
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
10k
TA
R
SR
MASTER
⎞
⎠ ⎟
V
3.3V
IN
• V
R
10k
R
6.65k
4V TO 5.5V
C
TB
TA
TRACK
SR
10µF
10µF
RUN
RUN
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 R
3. APPLY AN EXTERNAL TRACKING RAMP DIRECTLY
V
SV
RUN1
PLLLPF1
MODE1
PHMODE1
TRACK1
V
SV
RUN2
PLLLPF2
MODE2
PHMODE2
TRACK2
IN1
IN2
IN1
IN2
SW1
SW2
CLKIN1
CLKIN1
SGND1
CLKOUT1 CLKIN2
LTM4616
GND1
SR
output, then the slave will coincident track with the master
until it reaches its final value. The master will continue to
its final value from the slave’s regulation point. Voltage
tracking is disabled when V
Figure 5 will be equal to R
The track pin of the master can be controlled by an external
ramp or by R
RC ramp time can be programmed using equation:
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
AND C
SGND2
t = – ln 1–
SR
TIED TO V
CLKOUT2
⎛
⎜
⎝
GND2
⎛
⎝ ⎜
SR
IN
PGOOD1
PGOOD2
WITH t = –(ln(1–0.596/V
BSEL1
BSEL2
MGN1
MGN2
V
V
I
I
4616 F05
and C
THM1
THM2
OUT1
OUT2
0.596V
I
I
FB1
FB2
TH1
TH2
V
IN
SR
PGOOD
BSEL
in Figure 5 referenced to V
⎞
⎠ ⎟
R
2.21k
R
6.65k
TRACK
FB1
FB2
• R
FB
for coincident tracking.
SR
IN
) • R
is more than 0.596V. R
• C
100µF
100µF
SR
SR
• C
SR
⎞
⎟
⎠
LTM4616
))
V
IN
50k
50k
100µF
MASTER
3.3V/7A
SLAVE
1.5V/8A
15
IN
. The
TA
4616fc
in