UNR-1.8/2-D5SM データシートの表示（PDF） - DATEL Data Acquisition products

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UNR-1.8/2-D5SM

Surface-Mount, Non-Isolated 1.8/2.5/3.3V, 3.6-10W DC/DC Converters

DATEL Data Acquisition products  

NON-ISOLATED, 3.6-10W, SURFACE-MOUNT DC/DC CONVERTERS

SM Models

On/Off Control

The On/Off Control pin (pin 3) may be used for remote on/off operation. UNR

SM Series converters are designed so that they are enabled when the control

pin is pulled high or left open (normal mode) and disabled when the control pin is

pulled low (to less than +0.8V relative to Logic Ground, pin 2). As shown in the

figure and table below, each device has an internal pull-up resistor on its On/Off

Control pin whose value and voltage vary with model.

Dynamic control of the on/off function is best accomplished with a mechanical

relay or an open-collector/open-drain drive circuit (optically isolated if appropri-

ate). The drive circuit should obviously be able to sink appropriate current when

activated and withstand appropriate voltage when deactivated.

Applying an external voltage to pin 3 when no input power is applied to the

converter can cause permanent damage to the converter. The on/off control

function, however, is designed such that the converter can be disabled (pin 3

pulled low) while input power is ramping up and then "released" once the

input has stabilized. The time duration between the point at which the converter

is released and its fully loaded output voltage settles to within specified

accuracy can be found in the Performance/Functional Specifications Table.

9

VIP

+INPUT

REP

RIP

3

ON/OFF

CONTROL

2

LOGIC GROUND

Figure 2. Driving the On/Off Control Pin

Model

Internal

Pull-Up

Resistor (RIP)

UNR-1.8/2-D5SM

UNR-2.5/2-D5SM

UNR-3.3/3-D5SM

UNR-3.3/3-D12SM

1kΩ

1kΩ

1kΩ

10kΩ

External

Internal

Pull-Up

Pull-Up

Resistor (REP) Voltage (VIP)

15kΩ

1.8V

N.A.

2.5V

N.A.

3.3V

N.A.

VIN

Solder Reflow

For UNR SM Series devices, the packages' gull-wing leads are made of

tin-plated (150 microinches) copper. The gull-wing configuration, as opposed to

"J" leads, was selected to keep the solder joints out from under the package

to minimize both heat conduction away from the leads (into the encapsulated

package) and IR shadowing effects. Through a series of experiments, using

8 mil-thick, 63/37/2 (lead/tin/silver) solder paste and single-layer test boards, we

have determined an optimal solder-reflow temperature profile as shown in Figure

2. Obviously, your optimal profile will be a function of many factors including

paste thickness, board thickness, number of conductive layers, copper weight,

the density of surrounding components, etc.

The profile in Figure 3 should be used as a starting point for your own

experiments. If you'd like, DATEL can provide you with complimentary "dummy"

units to be used in such tests. Under no circumstances should the peak

temperature exceed +235°C for an extended period of time.

As shown in Figure 4, our tests have determined the optimal landing-pad size

to be 160 mils by 130 mils.

260

240

220

200

180

160

140

120

100

80

60

40

20

0

0

SOLDER

REFLOW

PEAK

TEMP.

235°C

PRE-HEAT AND TEMPERATURE SOAK

30

60

90

120

150

180

210

240

Time (Seconds)

Figure 3. Optimal Solder Reflow Profile

270

300

0.015

(0.38)

0.130* 0.100**

(3.30) (2.54)

* PAD DIMENSION

** LEAD DIMENSION

0.160*

(4.06)

0.110**

(2.79)

Figure 4. PC Board Land Pattern

5

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