JAHW075A Lineage Power, JAHW075A Datasheet - Page 10

• Manufacturer Part Number: JAHW075A
• Manufacturer: Lineage Power

dc-dc Converters; 36 to 75 Vdc Input, 5 Vdc Output; 50 to 100 W
Design Considerations
Input Source Impedance
The power module should be connected to a low
ac-impedance input source. Highly inductive source
impedances can affect the stability of the power mod-
ule. For the test configuration in Figure 19, a 33 µF
electrolytic capacitor (ESR < 0.7 Ω at 100 kHz)
mounted close to the power module helps ensure sta-
bility of the unit. For other highly inductive source
impedances, consult the factory for further application
guidelines.
Output Capacitance
High output current transient rate of change (high di/dt)
loads may require high values of output capacitance to
supply the instantaneous energy requirement to the
load. To minimize the output voltage transient drop dur-
ing this transient, low E.S.R. (equivalent series resis-
tance) capacitors may be required, since a high E.S.R.
will produce a correspondingly higher voltage drop dur-
ing the current transient.
Output capacitance and load impedance interact with
the power module’s output voltage regulation control
system and may produce and ‘unstable’ output condi-
tion for the required values of capacitance and E.S.R..
Minimum and maximum values of output capacitance
and of the capacitor’s associated E.S.R. may be dic-
tated, depending on the modules control system.
The process of determining the acceptable values of
capacitance and E.S.R. is complex and is load-depen-
dant. Lineage provides Web-based tools to assist the
power module end-user in appraising and adjusting the
effect of various load conditions and output capaci-
tances on specific power modules for various load con-
ditions.
1. Access the web at www.LineagePower.com
2. Under Products, click on the DC-DC link
3. Under Design Tools, click on Application Tools Download
4. Various design tools will be found, including tools for determining
10
10
§Not available for all codes, Where not available, use minimum values in table
stability of power module systems
above
§
.
Safety Considerations
For safety-agency approval of the system in which the
power module is used, the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standard,
i.e., UL60950, CSA C22.2 No. 60950-00, and VDE
0805 (IEC60950, IEC950).
If the input source is non-SELV (ELV or a hazardous
voltage greater than 60 Vdc and less than or equal to
75 Vdc), for the module’s output to be considered
meeting the requirements of safety extra-low voltage
(SELV), all of the following must be true:
n
n
n
n
Note: Do not ground either of the input pins of the
The power module has extra-low voltage (ELV) outputs
when all inputs are ELV.
The input to these units is to be provided with a maxi-
mum 15 A normal-blow fuse in the ungrounded lead.
Feature Descriptions
Overcurrent Protection
To provide protection in an output overload condition,
the unit is provided with internal shut down and auto-
restart mechanism.
At the instance of current-limit inception, the module
enters a "hiccup" mode of operation whereby it shuts
down and automatically attempts to restart. As long as
the fault persists, the module remains in this mode.
The protection mechanism is such that the unit can
continue in this condition for a sufficient interval of time
until the fault is cleared.
A latch-off option is also available
The input source is to be provided with reinforced
insulation from any hazardous voltages, including the
ac mains.
One V
both the input and output pins are to be kept floating.
The input pins of the module are not operator acces-
sible.
Another SELV reliability test is conducted on the
whole system, as required by the safety agencies, on
the combination of supply source and the subject
module to verify that under a single fault, hazardous
voltages do not appear at the module’s output.
module without grounding one of the output pins.
This may allow a non-SELV voltage to appear
between the output pin and ground.
I
pin and one V
O
pin are to be grounded, or
Lineage Power
April 2008