BMP25-40W Datel, Inc., BMP25-40W Datasheet - Page 6

• Manufacturer Part Number: BMP25-40W
• Manufacturer: Datel, Inc.

On/Off Control (Standard)
The On/Off Control pin (pin 5) may be used for remote on/off operation. As
shown in Figure 6, the control pin has an internal 10k
approximately 10V. The converter is designed so that it is enabled when the
control pin is left open (normal mode) and disabled when the control pin is
pulled low (to less than +0.8V relative to –Input, pin 2).
Dynamic control of the on/off function is best accomplished with a mechani-
cal relay or an open-collector/open-drain drive circuit (optically isolated if
appropriate). The drive circuit should obviously be able to sink approximately
1mA when activated and withstand more than 10 Volts when deactivated.
Applying an external voltage to pin 5 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 5
pulled low) while input power is ramping up and then "released" once the
input has stabilized. Under these circumstances, it takes approximately
30ms for the output of the fully loaded DC/DC to ramp up and settle to within
±1% of its final value after the converter has been turned on.
Synchronization (Optional)
In critical applications employing multiple switching DC/DC converters, it may
be desirable to intentionally synchronize the switching of selected converters
(so the system noise can be reduced with notch filtering) or to purposely
desynchronize the converters (to lessen the current-carrying requirements on
intermediate dc buses). BMP DC/DC Converters have been designed so that
the On/Off Control function on pin 5 can be replaced with a Sync function. This
change has to be implemented by DATEL during the product assembly
process. Contact our Applications Engineering Group for additional details.
To synchronize the switching of multiple BMP converters configured with the
Sync function, an external clock can be applied to pin 5 of each converter.
The clock should be a TTL square wave referenced to –Input (logic high =
+2 to +5 Volts, 250µA max.; logic low = 0 to +0.8 Volts, 70µA max.) with a
maximum 1µsec "high" duration. The frequency of the synchronizing clock
should be higher than that of any individual converter. Therefore, it should be
145kHz ±5kHz.
Output Trimming
The total output voltage span, from +Output (pin 9) to –Output (pin 6) may
be trimmed ±5% via a single trimpot or fixed resistor. The trimpot should be
connected as shown in Figure 8 with its wiper connected to pin 10 (Trim). A
trimpot can also be used to determine the value of a single fixed resistor
which can be connected between pin 10 (Trim) and pin 9 (+Output) to trim
"down" the output voltages, or between pins 10 (Trim) and 6 (–Output) to
trim "up" the output voltages. Fixed resistors should be metal-film types with
absolute TCR's less than 100ppm/°C to ensure stability.
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: [phone] [phone] Fax: [phone]
Internet: www.datel.com
Data Sheet Fax Back: [phone]
DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions
contained herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. The DATEL logo is a registered DATEL,
Inc. trademark.
XMP Series
®
INNOVATION and EX C ELL E N C E
Email: [e-mail]
®
pull-up resistor to
ISO-9001 REGISTERED
6 6
2 5 - 4 0 W , D U A L
Case Connection
Unlike most other DC/DC converters, BMP DC/DC's do not have their metal
case connected to one of their input pins. The "uncommitted" case is
connected to pin 4 which, depending on your system configuration, should be
connected to either +Input (pin 3) or –Input (pin 2).
DATEL (UK) LTD. Tadley, England Tel: [phone]
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: [phone]
DATEL GmbH München, Germany Tel: [phone]
DATEL KK Tokyo, Japan Tel: [phone], Osaka Tel: [phone]
C
2
3
IN
+
+INPUT
–INPUT
Figure 8. Trim Connections Using a Trimpot
2
3
Figure 6. Driving the On/Off Control Pin
to Reduce Input/Output Ripple/Noise
Figure 7. Using External Capacitors
O U T P U T
+INPUT
–INPUT
3
5
2
+OUTPUT
–OUTPUT
+INPUT
COMMON
ON/OFF
CONTROL
–INPUT
TRIM
D C / D C
+OUTPUT
–OUTPUT
COMMON
+10V
10
9
6
8
10k
C O N V E R T E R S
20k
5-10
Turns
9
8
6
DS-0411
+
+
LOAD
LOAD
C
C
OUT
OUT
11/01