Tyco Electronics Corp. 9
Data Sheet CC030-Series Power Modules; dc-dc Converters:
January 2000 18 Vdc to 36 Vdc Inputs, 30 W
Design Considerations (continued)
Input Source Impedance
The power module should be connected to a low
ac-impedance input source. Source inductance greater
than 12 µH can aff ect the stability of the pow er module.
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. (See Figure 14.)
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.,
UL
1950,
CSA
C22.2 No. 950-95, and
VDE
0805
(EN60950, IEC950).
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the
input must meet SELV requirements.
The pow er module has e xtr a-low voltage (ELV) outputs
when all inputs are ELV.
The input to these units is to be provided with a maxi-
mum 5 A normal-blow fuse in the ungrounded lead.
Feature Descriptions
Overcurrent Protection
To provide protection in a fault (output overload) condi-
tion, the unit is equipped with internal current-limiting
circuitry and can endure current limiting for an unlim-
ited duration. At the point of current-limit inception, the
unit shifts from voltage control to current control. If the
output voltage is pulled very low during a severe fault,
the current-limit circuit can e xhibit either foldback or tai-
lout characteristics (output-current decrease or
increase). The unit operates normally once the output
current is brought back into its specified range.
Remote On/Off
To turn the power module on and off, the user must
supply a switch to control the voltage between the
on/off terminal and the VI(–) terminal (Von/off). The
switch can be an open collector or equivalent (see
Figure 16). A logic low is Von/off = –0.7 V to 1.2 V, during
which the module is off. The maximum Ion/off during a
logic low is 1 mA. The switch should maintain a logic-
low voltage while sinking 1 mA.
During a logic high, the maximum Von/off generated by
the power module is 6 V. The maximum allowable leak-
age current of the switch at Von/off = 6 V is 50 µA.
The module has internal capacitance to reduce noise
at the ON/OFF pin. Additional capacitance is not gen-
erally needed and may degrade the start-up character-
istics of the module.
8-720(C).i
Figure 16. Remote On/Off Implementation
Remote Sense
Remote sense minimizes the effects of distribution
losses by regulating the voltage at the remote-sense
connections. The voltage between the remote-sense
pins and the output terminals must not exceed the out-
put voltage sense range giv en in the Feature Specifica-
tions table, for example, for the CC030Bs:
[VO(+) – VO(–)] – [SENSE(+) – SENSE(–)] ≤ 0.5 V
The voltage between the VO(+) and VO(–) terminals
must not exceed 13.2 V. This limit includes any
increase in voltage due to remote-sense compensa-
tion, set-point adjustment, and trim (see Figure 17).
+
Ion/off
–
Von/off
REMOTE
ON/OFF
VI(+)
VI(–) SENSE(+)
SENSE(–)
VO(+)
VO(–) LOAD