bcp-3.3-2.5 C&D Technologies., bcp-3.3-2.5 Datasheet - Page 4

• Manufacturer Part Number: bcp-3.3-2.5
• Description: 3.3v And 2.5v, Half-brick 50 Watt, Dc/dc Converters
• Manufacturer: C&D Technologies.

3.3V & 2.5V Outputs/Returns
The BCP Series outputs (pins 7 & 10) and returns (pins 6 & 9) are isolated
from the +V
transistors.
The 3.3V Return (pin 6) and 2.5V Return (pin 9) are connected internal to
the DC/DC converter. Though the returns are common within the DC/DC
converter, the regulating control loop for each output is sensed directly at
its respective output and return pins.To maintain optimum regulation when
a ground plane is not used, it is critical that PC board layouts return each
output to its corresponding return pin.
Filtering and Noise Reduction
All BCP DC/DC Converters achieve their rated ripple and noise specifications
using the external input and output capacitors specified in the Performance/
Functional Specifications table. In critical applications, input/output noise may
be further reduced by installing additional external I/O caps. Input capacitors
should be selected for bulk capacitance, low ESR and high rms-ripple-current
ratings. Input capacitors serve as energy-storage devices to minimize varia-
tions in line voltage caused by transient IR drops in PCB conductors from
backplane to the DC/DC. Output capacitors should be selected for low ESR
and appropriate frequency response. All caps should have appropriate volt-
age ratings and be mounted as close to the converters as possible.
The most effective combination of external I/O capacitors will be a function
of your particular load and layout conditions. Our Applications Engineers can
recommend potential solutions and can discuss the possibility of our modify-
ing a device’s internal filtering to meet your specific requirements. Contact our
Applications Engineering Group for additional details.
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 sustained, non-current-limited, input-voltage polarity
reversals exists. For DATEL BCP DC/DC Converters, you should use slow-
blow type fuses with values no greater than the following.
Fuses should be installed in the +Input line.
Input Overvoltage/Undervoltage Shutdown and Start-Up Threshold
Under normal start-up conditions, devices will not begin to regulate until
the ramping-up input voltage exceeds the Start-Up Threshold Voltage (35V
for "D48" models). Once operating, devices will not turn off until the input
voltage drops below the Undervoltage Shutdown limit (32V for "D48" models).
Subsequent re-start will not occur until the input is brought back up to the
Start-Up Threshold. This built-in hysteresis prevents any unstable on/off
situations from occurring at a single voltage.
Input voltages exceeding the input overvoltage shutdown specification listed
in the Performance/Functional Specifications will cause the device to shut-
down. A built-in hysteresis (2V typical for "D24" models, 4V typical for
"D48" models) will not allow the converter to restart until the input voltage
is sufficiently reduced.
www.cd4power.com
www.cd4power.com
P O W E R E L E C T R O N I C S D I V I S I O N
T E C H N I C A L N O T E S
"D24" Models
"D48" Models
V
IN
IN
and –V
Range
IN
inputs (pins 4 & 1) via a transformer and opto-coupled
Fuse Value
6 Amps
3 Amps
Start-Up Time
The V
a ramping input voltage crosses the turn-on threshold point and the fully-
loaded output voltage enters and remains within its specified accuracy band.
Actual measured times will vary with input source impedance, external input
capacitance, and the slew rate and final value of the input voltage as it
appears to the converter.
The On/Off to V
voltage applied but is turned off via the On/Off Control. The specification
defines the interval between the time at which the converter is turned on
and the fully loaded output voltage enters and remains within its specified
accuracy band.
On/Off Control (Standard feature)
The On/Off Control (pin 3) may be used for remote on/off operation. As shown
in Figure 1A, the control pin is referenced to the –Input (pin 1). The standard
BCP converter (no suffix) is designed so that it is enabled when the control
pin is left open and disabled when the control pin is pulled low (to less than
+0.8V relative to –Input).
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
appropriate). The drive circuit should be able to sink approximately 1mA for
logic low.
The on/off control function is designed such that the converter can be dis-
abled (pin 3 pulled low for no-suffix models) while input power is ramping up
and then "released" once the input has stabilized.
For BCP converters configured with a negative-polarity option ("N" suffix
added to part number), operation is opposite to that described above. The
converter is disabled when the On/Off Control pin is left open and enabled
when pulled low.
IN
to V
50W, Dual Output, Mixed-Voltage DC/DC Converters
4
3
1
OUT
Figure 1A. No Suffix
+INPUT
ON/OFF
CONTROL
–INPUT
start-up time is the interval between the time at which
OUT
start-up time assumes the converter has its nominal input
+13V
+3V
D C / D C C O N V E R T E R S
BCP Models
MDC_BCP50W_A01
Figure 1B. "N" Suffix
4
3
1
+INPUT
ON/OFF
CONTROL
–INPUT
Page 4 of 6