MPQ24S24-50C Wall Industries,Inc., MPQ24S24-50C Datasheet - Page 4

• Manufacturer Part Number: MPQ24S24-50C
• Description: 50 W Dc-dc Converter 10-36 Vdc Input 24 Vdc Output At 2.5 A Quarter-brick Package
• Manufacturer: Wall Industries,Inc.

WALL INDUSTRIES, INC.
TECHNICAL DATASHEET
Rev. C
MPQ24S24-50C
DESIGN CONSIDERATIONS
Under Voltage Lock Out (UVLO)
The converter output is disabled until the input voltage exceeds the UVLO turn-on limit. The converter will remain ON until the input
voltage falls below the UVLO turn-off limit.
Over Current Protection
The converter is protected from short circuit and over current conditions. Upon sensing an over current, the output will begin to drop (or
‘foldback’) limiting the output power. Further increasing the output current will cause the converter to shut off and then restart (or
‘hiccup’) until the overcurrent condition is removed. Shorting the output will cause the converter to immediately enter the ‘hiccup’ mode.
Over Temperature Protection
The converter is protected from over temperature conditions. Upon exceeding this temperature, the converter will shut down. The
converter will automatically recover once the over tempature condition is removed.
Input Filter
No additional input capacitor is needed for the power supply to operate. However, due to the low voltage, high input current nature of the
power supply, it is highly recommended that a minimum 100 uF/50 V electrolytic type input bulk capacitor be added to reduce input
ripple voltage and current. Refer to Photos 1 and 2 for an example. For an even further reduction of input ripple, an inductor may be
placed between the source and the previously mentioned capacitor. Additionally, a 1-10 uF ceramic capacitor may be added in front of
the inductor to form pi-filter. No inductor should be placed between the capacitor and the input to the converter.
Output Filter
No additional output capacitor is needed for the power supply to operate. However, to reduce the ripple and noise on the output,
additional capacitance may be added. Usually, a ceramic capacitor between 0.1 and 1 uF is recommended for reducing any ringing and
spike noise. Also, capacitance in the form of an aluminum electrolytic capacitor may also be placed across the output in order reduce
ripple, and improve the transient peak-to-peak voltage deviation (see Photos 7 to 11), but in most cases, is not necessary.
Remote Sense
To improve regulation at the load, route the connections from the -Sense and the +Sense pins to the –Vout and +Vout connections at the
load. This will force the converter to regulate the voltage at the load and not at the pins of the converter. If it is not desired to use the
Remotes Sense feature, the –Sense and +Sense pins should be shorted to the -Vout and +Vout pins respectively. However, no damage to
the converter will occur if the Sense pins are left open.
Fusing
It is required that the input to the converter be supplied with a maximum 10 A, 250 V rated fuse UL Listed or R/C fuse.
Safety
The MPQ24 series is designed to meet EN60950 Safety of Information Technology Equipment. The isolation provided by the MPQ24
series is a Basic insulation in accordance with EN60950. SELV output reliability is maintained only if the input to the converter is a
SELV source. To maintain SELV reliability, if either +Vin or –Vin is connected to chassis, either +Vout or –Vout must also be
connected to chassis. Otherwise, both the input and the output must not be connected to chassis.
PCB Layout Considerations
Due to the Basic isolation provided by the converter, caution must be observed in routing traces more than 2 mm inward of any input or
output pins on the top layer of the pcb board underneath the converter. Also, due to noise coupling and isolation requirements, no power
or ground planes or any signal traces should be routed on the top layer of the pcb underneath the converter. Due to comon noise coupling,
input or output power and ground planes should not be poured across the input to output on any layers underneath the converter. Instead,
it is best to provide separate input and output power and ground traces on the bottom or an inner layer with a miminum of 1 mm
separation between traces on the same layer.
Lastly, as the case/heatsink is floating metal, caution must also be observed to provide appropriate spacing (minimum 1.4 mm for
Pollution degree 2 Material Group IIIa + IIIb) around the case/heatsink or risk reducing the input to output spacing and violating Basic
insulation requirements.
(888) 597-WALL
www.wallindustries.com
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