GE Industrial Solutions 16V PicoTLynx 4A - Manual (Page 17)

GE
Data Sheet
16V PicoTLynx TM 4A: Non-Isolated DC-DC Power Modules
8Vdc –16Vdc input; 0.6Vdc to 8.0Vdc output; 4A Output Current
September 10, 2013 ©2013 General Electric Company. All rights reserved. Page 17
Programming Tool, available at www.lineagepower.com under
the Design Tools section, also calculates the values of R
margin-up
and R
margin-down
for a specific output voltage and % margin.
Please consult your local Lineage Power technical representative
for additional details.
Vo
MODULE
GND
Trim
Q1
Rtrim
Rmargin-up
Q2
Rmargin-down
Figure 58. Circuit Configuration for margining Output
voltage.
Monotonic Start-up and Shutdown
The 16V PicoTLynx TM 4A modules have monotonic start-up and
shutdown behavior for any combination of rated input voltage,
output current and operating temperature range.
Startup into Pre-biased Output
The 16V PicoTLynx TM 4A modules can start into a prebiased
output as long as the prebias voltage is 0.5V less than the set
output voltage. Note that prebias operation is not supported
when output voltage sequencing is used.
Power Good
The 16V PicoTLynx TM 4A modules provide a Power Good
(PGOOD) signal that is implemented with an open-drain output
to indicate that the output voltage is within the regulation
limits of the power module. The PGOOD signal will be de-
asserted to a low state if any condition such as
overtemperature, overcurrent or loss of regulation occurs that
would result in the output voltage going ±10% outside the
setpoint value. The PGOOD terminal should be connected
through a pullup resistor (suggested value 100K
Ω) to a source
of 5VDC or lower.
Tunable Loop TM
The 16V PicoTLynx TM 4A modules have a new feature that
optimizes transient response of the module called Tunable
Loop TM .
External capacitors are usually added to the output of the
module for two reasons: to reduce output ripple and noise (see
Fig. 53) and to reduce output voltage deviations from the
steady-state value in the presence of dynamic load current
changes. Adding external capacitance however affects the
voltage control loop of the module, typically causing the loop
to slow down with sluggish response. Larger values of external
capacitance could also cause the module to become unstable.
The Tunable Loop TM allows the user to externally adjust the
voltage control loop to match the filter network connected to
the output of the module. The Tunable Loop
TM is implemented
by connecting a series R-C between the SENSE and TRIM pins
of the module, as shown in Fig. 59. This R-C allows the user to
externally adjust the voltage loop feedback compensation of
the module.
MODULE
VOUT
SENSE
TRIM
GND
RTUNE
CTUNE
RTrim
C O
Figure. 59. Circuit diagram showing connection of R
TUME
and
C
TUNE
to tune the control loop of the module.
Recommended values of R
TUNE
and C
TUNE
for different output
capacitor combinations are given in Tables 2 and 3. Table 2
shows the recommended values of R
TUNE
and C
TUNE
for
different values of ceramic output capacitors up to 470 μF that
might be needed for an application to meet output ripple and
noise requirements. Selecting R
TUNE
and C
TUNE
according to
Table 2 will ensure stable operation of the module.
In applications with tight output voltage limits in the presence
of dynamic current loading, additional output capacitance will
be required. Table 3 lists recommended values of R
TUNE
and
C
TUNE
in order to meet 2% output voltage deviation limits for
some common output voltages in the presence of a 2A to 4A
step change (50% of full load), with an input voltage of 16V.
Please contact your Lineage Power technical representative to
obtain more details of this feature as well as for guidelines on
how to select the right value of external R-C to tune the
module for best transient performance and stable operation
for other output capacitance values or input voltages other
than 16V.
Table 2. General recommended values of of R
TUNE
and C
TUNE
for Vin=12V and various external ceramic capacitor
combinations.
Vo=6.5