BWR-5/6-3.3/7-D12 데이터 시트보기 (PDF) - DATEL Data Acquisition products

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BWR-5/6-3.3/7-D12

Dual Output Mixed Voltage, BWR Models 5V and 3.3V, 2 x 2 33 Watt, DC/DC Converters

DATEL Data Acquisition products  

XWR Series

33W, DUAL OUTPUT, MIXED-VOLTAGE DC/DC CONVERTERS

Isolation / Case Connection

The BWR 33 Watt Series’ 5V and 3.3V outputs (pins 5 & 7) and return (pin

6) are isolated from the +VIN and –VIN inputs (pins 1 & 2) via a transformer

and an opto-coupled transistor. Case connections are made internal to the

DC/DC converter. "D12 & D24" cases are connected to –Input (pin 2), "D48"

to +Input (pin 1).

Input Reverse-Polarity Protection

Upon applying a reverse-polarity voltage to the DC/DC converter, an internal

diode will be forward biased, drawing excessive current from the power

source. Therefore, it is required that the input current be limited be either an

appropriately rated input fuse or a current limited power source.

Input Fusing

Certain applications and/or safety agencies may require the installation of

fuses at the inputs of power conversion components. Fuses should also

be used if the possibility of a sustained, non-current-limited, input-voltage

polarity reversal exists. For DATEL BWR 33 Watt Series Converters, slow

blow fuses are recommended with values no greater than the following.

VIN Range

"D12" Models

"D24" Models

"D48" Models

Fuse Value

6 Amps

4 Amps

2 Amps

It is recommended that fuses be installed in the +Input line.

Trimming Output Voltages

These BWR converters have a trim capability (pin 8) that allow users to

adjust the output voltages ±5%. A trim adjustment will cause an equal

percentage of change in both outputs. Adjustments to the output voltages

can be accomplished via a trim pot Figure 3 or a single fixed resistor as

shown in Figures 4 and 5. A single fixed resistor can increase or decrease

the output voltage depending on its connection. Fixed resistors should

be metal-film types with absolute TCR’s less than 100ppm/°C to minimize

sensitivity to changes in temperature.

A single resistor connected from the Trim Pin (pin 8) the +3.3V Output (pin

7), see Figure 4, will decrease the output voltages. A resistor connected

from the Trim Pin (pin 8) to Output Return (pin 6) will increase the output

voltages.

Table 1 shows the typical Trim Resistor values for output voltage changes

of 1 through 5%.

Trim adjustment greater than 5% can have an adverse affect on the convert-

er’s performance and is not recommended.

Trim Down

0%

–

1%

201.5k

2%

92.5k

3%

56.1k

4%

38k

5%

27.1k

Trim Up

–

123.7k

55.3k

32.6k

21.2k

14.3k

Table 1. Percentage of Output Voltage Change vs Trim Resistor Value (Ohms)

1

+INPUT

2

–INPUT

5

+5V OUTPUT

OUTPUT 6

RETURN

4 ON/OFF

CONTROL

7

+3.3V OUTPUT

TRIM

8

+5V LOAD

20kΩ

5-22 +3.3V LOAD

Turns

Figure 3. Trim Connections using a Trimpot

1

+INPUT

5

+5V OUTPUT

+5V LOAD

2

–INPUT

OUTPUT 6

RETURN

+3.3V LOAD

4 ON/OFF

CONTROL

7

+3.3V OUTPUT

TRIM

8

R TRIM

DOWN

Figure 4. Decrease Output Voltage Trim Connections

Using A Fixed Resistor

Trim Down

e j RTDOWN (kΩ) =

3.55(VO – 1.273)

3.3 – VO

–13

1

+INPUT

5

+5V OUTPUT

+5V LOAD

2

–INPUT

OUTPUT 6

RETURN

+3.3V LOAD

4 ON/OFF

CONTROL

7

+3.3V OUTPUT

TRIM

8

R TRIM

UP

Figure 5. Increase Output Voltage Trim Connections

Using A Fixed Resistor

Trim Up

e j RTUP (kΩ) =

4.51

VO – 3.3

–13

Note: Accuracy of adjustment is subject to the tolerances of resistor

values, reference accuracy and factory-adjusted output accuracy.

VO = desired output voltage.

6

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