bcp-5-3.3 C&D Technologies., bcp-5-3.3 Datasheet - Page 6

• Manufacturer Part Number: bcp-5-3.3
• Description: Dual Output, Mixed Voltage, Isolated 5v & 3.3 V, Half-brick 75 W Dc/dc Converters
• Manufacturer: C&D Technologies.

Output Overvoltage Protection
Each voltage output of the BCP Series converter is independently moni-
tored via an auxiliary winding in the output inductor. If the output voltage
should rise to a level which could be damaging to the load circuitry (see
Performance/Functional Specifications for limits), the overvoltage circuitry
will power down the PWM controller and latch off the DC/DC converter. The
device must now be restarted by powering cycling V
Current Limiting
When output current demands exceed the maximum output current rating
by 107% to 133%, the DC/DC converter will go into a current limiting
mode. In this condition the output voltage decreases proportionately as the
output current increases, thereby maintaining a somewhat constant power
dissipation—referred to as Power Limiting (see Figure 2). As the load
approaches a short circuit, the output current will continue to increase until
it reaches the rated Short Circuit Current limit.
Short Circuit Condition
As described under "Current Limiting," when the BCP Series DC/DC converter
output is subjected to a short circuit condition, the output current will remain at
the Short Circuit Current limit. In this state there is negligible power dissipated
in the load. Therefore, most of the input power is dissipated within the con-
verter, causing the internal temperature to increase. If this condition persists,
Thermal Shutdown will activate and shutdown the DC/DC converter. When the
internal temperature is sufficiently decreased, the converter will self-start.
Thermal Shutdown
The BCP Series is equipped with Thermal Shutdown circuitry. If the internal
temperature of the DC/DC converter rises above the designed operating tem-
perature, 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.
6.00
5.00
4.00
3.00
2.00
1.00
0
BCP-5/15-3.3/15-D24, D48 Current Limiting Characteristics
(Nominal V
IN
)
Figure 2. Current Limiting Characteristics
3.3V Output
Output Current, I
OUT
5V Output
(Amps)
www.murata-ps.com
IN
.
Input Reverse-Polarity Protection
Upon applying a reverse-polarity voltage to the DC/DC converter, an internal
diode will be forward biased and draw 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.
Heat Sinks for BCP Series
MPS offers two standard heat sinks that can be mounted to the half-brick
package to extend the converter's operating temperature range. Along with the
standard 2.3" x 2.4" x 0.5" (HS-CP) heat sink, DATEL has designed a low-profile
heat sink for height-restricted applications. This new heat sink (HS-CPLP2) is
designed with radiant fins that extend 0.51" beyond either side of the 2.4"
dimension of the BCP package. The convenience of this design is that the finned
extensions protrude only 0.31" below the top surface of the DC/DC converter,
allowing components with a profile height less than 0.215" to be mounted on
the pc board below the heat sink. Therefore, while the surface area of the low-
profile heat sink measures 2.3" x 3.5", pcb real estate is unaffected.
low-profile heat sink should be mounted with the fins vertically oriented. Both
models are shipped with 0.009" sellf-adhesive thermal pad and mounting
screws.
For optimum thermal performance in a natural convection application, the
6
5
4
3
2
1
0
0
HS-CP and HS-CPLP2 Heat Sink Performance Vs. Air Flow
Dual Output, Mixed Voltage, Isolated 5V & 3.3 V,
100
Technical enquiries email: [e-mail], tel:
(@ 10.5 Watts Power Dissipation)
200
HS-CP
"Half-Brick" 75 W DC/DC Converters
AIR VELOCITY (FT./MIN.)
300
400
HS-CPLP2
MDC_BCP_75W.B02 Page 6 of 14
BCP Models
500
600
[phone]
700