July 14 2017 Preliminary A.01

TFR RAILWAY SERIES 24-Pin DIP

Up to 10 Watt DC-DC Converter

Operating Temperature Range

The TFR series of converters operates over the wide ambient temperature

range of -40

℃to+85℃.Deratingforthisseriesstartsabovethe

temperature of +60

℃.Thestandardmodelcasetemperatureshouldnot

go over +100

℃fornormaloperation.

Remote On/Off

The TFR series allows the user to switch the module on and off

electronically with the remote on/off feature. All models are available in

“positive logic” versions. The converter turns on if the Remote On/Off pin

is high (greater than 3.5 Volts) or open circuit. The converter will turn off

when the Remote On/OFF pin is low (Less than 1.2Votls) will turn the

converter off. The signal level of the Remote On/Off input is defined with

respect to ground. If the Remote On/Off pin is not used, the user should

leave the pin open and the converter will be on. Models with part number

option “N” are the “negative logic” remote on/off version. The unit turns

off if the remote On/Off pin is high (>3.5Vdc or open circuit). The converter

turns on if the on/off pin input is low (0 to<1.2Vdc). Note that the converter

is off by default.

Over Current Protection

All models have internal over current and continuous short circuit

protection. The unit operates normally once the fault condition is removed.

The converter will go into hiccup mode protection when it reach the

current limit condition.

Under Voltage Lock Out (UVLO)

Input under voltage lockout is standard on the TFR unit. The unit will shut

down when the input voltage drops below the threshold. On the other hand,

the unit will operate when the input voltage goes above the upper

threshold.

Over Voltage Protection

The over-voltage protection consists of a Zener diode that will limit the

output voltage.

Recommended PCB Layout/Footprints and Soldering

Information

The user must ensure that other components and metal in the vicinity of

the converter meet the spacing requirements to which the system is

approved. Low resistance and low inductance PCB layout should be used

where possible. Proper attention must also be given to low impedance

tracks between power module, input and output grounds. The

recommended footprints and soldering profiles are shown in the next two

figures.

Recommended PCB Footprint, Dimensions are in inches (millimeters)

Recommended Wave Soldering Profiles

Note：

1. Soldering Materials: Sn/Cu/Ni

2. Ramp up rate during preheating: 1.4

℃/Sec(From+50℃to+100℃)

3. Soaking temperature: 0.5

℃/Sec(From+100℃to+130℃),60±20

seconds

4. Peak temperature: +260

℃,above+250℃3~6Seconds

5. Ramp up rate during cooling: -10.0

℃/Sec(From+260℃to+150℃)

0

50

100

150

200

250

300

0

50

100

150

Time (Seconds)

Lead Free Wave Soldering Profile

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