Data Sheet
12V TLynxTM: Non-isolated DC-DC Power Modules
July 24, 2009
4.5 – 14Vdc input; 0.69Vdc to 5.5Vdc output; 20A output current
pullup resistor (suggested value 100KΩ) to a source of
6VDC or less.
MODULE
VIN+
Synchronization
The 12V TLynxTM series of modules can be
synchronized using an external signal. Details of the
SYNC signal are provided in the Electrical
Specifications table. If the synchronization function is
not being used, leave the SYNC pin floating.
499K
+
-
OUT
R1
SEQ
10K
Tunable LoopTM
The 12V TLynxTM 20A modules have a new feature
that optimizes transient response of the module called
GND
Tunable LoopTM
.
Figure 47. Circuit showing connection of the
sequencing signal to the SEQ pin.
External capacitors are usually added to the output of
the module for two reasons: to reduce output ripple
and noise (see Figure 41) 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 LoopTM allows the user to externally
adjust the voltage control loop to match the filter
network connected to the output of the module. The
Tunable LoopTM is implemented by connecting a series
R-C between the SENSE and TRIM pins of the
module, as shown in Fig. 47. This R-C allows the user
to externally adjust the voltage loop feedback
compensation of the module.
After the 10msec delay, an analog voltage is applied to
the SEQ pin and the output voltage of the module will
track this voltage on a one-to-one volt bases until the
output reaches the set-point voltage. To initiate
simultaneous shutdown of the modules, the SEQ pin
voltage is lowered in a controlled manner. The output
voltage of the modules tracks the voltages below their
set-point voltages on a one-to-one basis. A valid input
voltage must be maintained until the tracking and
output voltages reach ground potential.
When using the EZ-SEQUENCETM feature to control
start-up of the module, pre-bias immunity during start-
up is disabled. The pre-bias immunity feature of the
module relies on the module being in the diode-mode
during start-up. When using the EZ-SEQUENCETM
feature, modules goes through an internal set-up time
of 10msec, and will be in synchronous rectification
mode when the voltage at the SEQ pin is applied. This
will result in the module sinking current if a pre-bias
voltage is present at the output of the module. When
pre-bias immunity during start-up is required, the EZ-
SEQUENCETM feature must be disabled. For
additional guidelines on using the EZ-SEQUENCETM
feature please refer to Application Note AN04-008
“Application Guidelines for Non-Isolated Converters:
Guidelines for Sequencing of Multiple Modules”, or
contact the Lineage Power Technical representative
for additional information.
VOUT
SENSE
RTUNE
C O
MODULE
CTUNE
TRIM
Power Good
RTrim
GND
The 12V TLynxTM 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 ±11% outside the setpoint value. The
PGOOD terminal should be connected through a
Figure. 48. Circuit diagram showing connection of
RTUME and CTUNE to tune the control loop of the
module.
Recommended values of RTUNE and CTUNE for different
output capacitor combinations are given in Tables 2
and 3. Table 2 shows the recommended values of
R
TUNE and CTUNE for different values of ceramic output
capacitors up to 940μF that might be needed for an
LINEAGE POWER
17
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