SMLW010 datasheet(7/16 Pages) MACOM

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Data Sheet

January 2002

Power Modules: 36 Vdc to 75 Vdc Input; 10 W

SMLW010 Single-Output Low-Profile

Tyco Electronics Corp.

Safety Considerations

SMLW Modules

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 60950, CSA C22.2 No. 60950-00, and VDE

0805 (EN60950).

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:

■ The input source is to be provided with reinforced

insulation from any other hazardous voltages, includ-

ing the ac mains.

■ One VI pin and one VO pin are to be grounded or

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.

Note: Do not ground either of the input pins of the

module without grounding one of the output

pins. This may allow a non-SELV voltage to

appear between the output pins and ground.

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 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 exhibit either foldback or

tailout characteristics (output-current decrease or

increase). The unit operates normally once the output

current is brought back into its specified range.

Remote On/Off

Positive logic remote on/off turns the module on during

a logic-high voltage on the remote ON/OFF pin, and off

during a logic low.

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 may be an open collector or equivalent (see

Figure 4). A logic low is Von/off = –0.7 V to 1.2V. 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 6V. 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.

8-758a

Figure 4. Remote On/Off Implementation

Output Voltage Adjustment

Output voltage set-point adjustment allows the user to

increase or decrease the output voltage set point of a

module. This is accomplished by connecting an exter-

nal resistor between the TRIM pin and either the VO(+)

or VO(–) pins. With an external resistor between the

TRIM and VO(+) pins (Radj-down), the output voltage set

point (VO, adj) decreases (see Figure 5). The following

equation determines the required external resistor

value to obtain an output voltage change from VO, nom to

VO, adj:

where Radj-down is the resistance value connected

between TRIM and VO(+), and G, H, and L are defined

in the table below.

Ion/off

Von/off

REMOTE

ON/OFF

VI(+)

VI(-)

Radj-down

VOadj

–

()G

VOnom

VOadj

–

()

---------------------------------------

–

Ω

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