BWR-5/6-3.3/7-D12L1 查看數據表（PDF） - DATEL Data Acquisition products

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BWR-5/6-3.3/7-D12L1

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

DATEL Data Acquisition products  

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

BWR Models

Current Limiting

When power demands from either output fall within 126% to 181% of the rated

output current, the DC/DC converter will go into a current limiting mode. In

this condition both output voltages will decrease proportionately with increases

in output current, thereby maintaining a somewhat constant power dissipa-

tion. This is commonly referred to as power limiting (see Figures 2a and

2b). Current limit inception is defined as the point where the full-power output

voltage falls below the specified tolerance. If the load current being drawn

from the converter is significant enough, the unit will go into a short circuit

condition. See "Short Circuit Condition."

Typical Current Limiting Characteristics for 3.3V Output

4

3

2

VIN NOM, VIN LO All Models

1

VIN HI D12, D24 Models

VIN HI

D48 Models

0

0

2

4

6

8

10

12

14

3.3 VOUT Average Ouput Current (Amps)

Figure 2a. Current Limiting Characteristics for 3.3V Output

Typical Current Limiting Characteristics for 5V Output

(3.3V Output @ 700mA)

5

4.5

4

3.5

3

2.5

2

VIN NOM, VIN LO

1.5

All Models

VIN HI D12, D24

1

Models

VIN HI

0.5

D48 Models

0

0

1

2

3

4

5

6

7

8

9

5 VOUT Average Ouput Current (Amps)

Figure 2b. Current Limiting Characteristics for 5V Output

Short Circuit Condition

When a converter is in current limit mode the output voltages will drop as the

output current demand increases (see figures 2a and 2b). If the output volt-

age drops too low, the magnetically coupled voltage used to develop primary

side voltages will also drop, thereby shutting down the PWM controller.

Following a time-out period of 5 to 15 milliseconds, the PWM will restart,

causing the output voltages to begin ramping to their appropriate values. If

the short-circuit condition persists, another shutdown cycle will be initiated.

This on/off cycling is referred to as "hiccup" mode. The hiccup cycling

reduces the average output current, thereby preventing internal temperatures

from rising to excessive levels. The BWR is capable of enduring an indefinite

short circuit output condition.

Thermal Shutdown

These BWR converters are equipped with Thermal Shutdown Circuitry. If

the internal temperature of the DC/DC converter rises above the designed

operating temperature, a precision temperature sensor will power down the

unit. When the internal temperature decreases below the threshold of the

temperature sensor the unit will self start.

Output Overvoltage Protection

Both output voltages are monitored for an overvoltage condition via magnetic

coupling to the primary side. If either output voltage should rise to a level

which could be damaging to the load circuitry, the sensing circuitry will power

down the PWM controller causing the output voltages to decrease. Following

a time-out of 5 to 15 milliseconds the PWM will restart, causing the output

voltages to ramp to their appropriate values. If the fault condition persists,

and the output voltages again climb to excessive levels, the overvoltage

circuitry will initiate another shutdown cycle. This on/off cycling is referred

to as "hiccup" mode.

5

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