JFW100B Lineage Power, JFW100B Datasheet - Page 14

• Manufacturer Part Number: JFW100B
• Manufacturer: Lineage Power

dc-dc Converters; 36 to 75 Vdc Input, 12 Vdc Output; 50 W to 150 W
Feature Descriptions
Output Overvoltage Protection
Recovery from latched shutdown is accomplished by
cycling the dc input power off for at least 1.0 second or
by toggling the primary or secondary referenced
remote on/off signal for at least 1.0 second.
The overvoltage shutdown set point can be lowered by
placing a resistor between the overvoltage trim
(OVTRIM) pin and SENSE(–) pin. This feature is useful
if the output voltage of the converter has been trimmed
down and a corresponding reduction in overvoltage trip
point is desired.
The resistance required from a given overvoltage nom-
inal set point is derived from the following equation:
Where:
R
V
Module Synchronization
Any module can be synchronized to any other module
or to an external clock using the SYNC IN or SYNC
OUT pins. The modules are not designed to operate in
a master/slave configuration; that is, if one module
fails, the other modules will continue to operate.
SYNC IN Pin
This pin can be connected either to an external clock or
directly to the SYNC OUT pin of another JFW150x or
FW300x module.
If an external clock signal is applied to the SYNC IN
pin, the signal must be a 500 kHz (±50 kHz) square
wave with a 4 Vp-p amplitude. Operation outside this
frequency band will detrimentally affect the perfor-
mance of the module and must be avoided.
If the SYNC IN pin is connected to the SYNC OUT pin
of another module, the connection should be as direct
as possible, and the V
shorted together.
Unused SYNC IN pins should be tied to V
SYNC IN pin is not used, the module will operate from
its own internal clock.
14
14
ov-set
ov-adj
R
ov
is the value of an external resistor between the
OVTRIM pin and SENSE(–) pin.
is the nominal adjusted set point of the overvolt-
age shutdown threshold.
-
adj
=
⎛
⎝
14.7 2 V
--------------------------------------- -
V
ov-set
–
I
(–) pins of the modules must be
–
14.7
ov-set
⎞ kΩ
⎠
(continued)
(continued)
I
(–). If the
SYNC OUT Pin
This pin contains a clock signal referenced to the V
pin. The frequency of this signal will equal either the
module’s internal clock frequency or the frequency estab-
lished by an external clock applied to the SYNC IN pin.
When synchronizing several modules together, the
modules can be connected in a daisy-chain fashion
where the SYNC OUT pin of one module is connected
to the SYNC IN pin of another module. Each module in
the chain will synchronize to the frequency of the first
module in the chain.
To avoid loading effects, ensure that the SYNC OUT
pin of any one module is connected to the SYNC IN pin
of only one module. Any number of modules can be
synchronized in this daisy-chain fashion.
Forced Load Sharing (Parallel Operation)
For either redundant operation or additional power
requirements, the power module can be configured for
parallel operation with forced load sharing (see
Figure 26).
For a typical redundant configuration, Schottky diodes
or an equivalent should be used to protect against
short-circuit conditions. Because of the remote sense,
the forward-voltage drops across the Schottky diodes
do not affect the set point of the voltage applied to the
load. For additional power requirements, where multi-
ple units are used to develop combined power in
excess of the rated maximum, the Schottky diodes are
not needed.
An internal anti-rollback circuit prevents either output
voltage from falling more than 1 V below the other dur-
ing light load operation.
Good layout techniques should be observed for noise
immunity. To implement forced load sharing, the follow-
ing connections must be made:
n
n
n
The parallel pins of all units must be connected
together. The paths of these connections should be
as direct as possible.
All remote-sense pins must be connected to the
power bus at the same point. That is, connect all
remote-sense (+) pins to the (+) side of the power
bus at the same point, and connect all remote-sense
(–) pins to the (–) side of the power bus at the same
point. Close proximity and directness are necessary
for good noise immunity.
Add a 1000 pF capacitor across the PARALLEL pin
and SENSE(–) pin of each module. Locate the
capacitor as close to the module as possible.
Lineage Power
April 2008
I
(–)