Datasheet

LTC3616
21
3616fc
For more information www.linear.com/LTC3616
to the actual TRACK/SS pin voltage if the voltage value
is between 0.3V and 0.6V. Note: if TRACK/SS voltage is
0.6V, either the tracking circuit or the internal reference
can be used.
During up/down tracking the output current foldback is
disabled and the PGOOD pin is always pulled down (see
Figure 9).
applicaTions inForMaTion
Figure 8. DDR Pin Not Tied to S
VIN
Figure 9. DDR Pin Tied to SV
IN
. Example DDR Application
SOFT-START
STATE
t
SS
> 1ms
SHUTDOWN
STATE
0.6V
0.6V
0.2V
0V
0V
0V
0V
V
IN
V
IN
V
FB
PIN
VOLTAGE
TRACK/SS
PIN VOLTAGE
RUN PIN
VOLTAGE
SV
IN
PIN
VOLTAGE
RUN STATE RUN STATE
TIME
3616 F08
REDUCED
SWITCHING
FREQUENCY
DOWN
TRACKING
STATE
UP
TRACKING
STATE
SOFT-START
STATE
t
SS
> 1ms
SHUTDOWN
STATE
0.3V
0.45V
0.45V
0.3V
0.2V
0V
0V
0V
0V
V
IN
V
IN
V
FB
PIN
VOLTAGE
EXTERNAL
VOLTAGE
REFERENCE 0.45V
TRACK/SS
PIN VOLTAGE
RUN PIN
VOLTAGE
SV
IN
PIN
VOLTAGE
RUN STATE RUN STATE
TIME
3616 F09
REDUCED
SWITCHING
FREQUENCY
DOWN
TRACKING
STATE
UP
TRACKING
STATE
Efficiency Considerations
The efficiency of a switching regulator is equal to the output
power divided by the input power times 100%. It is often
useful to analyze individual losses to determine what is
limiting the efficiency and which change would produce
the most improvement. Efficiency can be expressed as:
Efficiency = 100% – (L1 + L2 + L3 + ...)
where L1, L2, etc. are the individual losses as a percent
-
age of input power.