BMP-5/3.338W Datel, Inc., BMP-5/3.338W Datasheet - Page 4

• Manufacturer Part Number: BMP-5/3.338W
• 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 +1.2V 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
1.5mA 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 fi nal 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 fi ltering) 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 confi gured 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.
Output Trimming
The total output voltage span of the 5 Volt output, from +5V Output (pin 9)
to Output Return (pin 8) may be trimmed ±5% via a single trimpot or fi xed
resistor. The trimpot should be connected as shown in Figure 3 with its wiper
connected to pin 10 (Trim). A trimpot can also be used to determine the value
of a single fi xed resistor which can be connected between pin 10 (Trim) and
pin 9 (+5V Output) to trim "down" the output voltages, or between pins 10
(Trim) and 8 (Output Return) to trim "up" the output voltages. Fixed resistors
should have absolute TCR's less than 100ppm/°C to ensure stability.
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 con-
nected to pin 4 which, depending on your system confi guration, should be
connected to either +Input (pin 3) or –Input (pin 2).
XMP Series
pull-up resistor to
4
Note: Resistor values are in k . Accuracy of adjustment is subject to
3 5 W , D U A L O U T P U T D C / D C C O N V E R T E R S
2
2
2
3
3
3
Figure 4. +5V
tolerances of resistors and factory-adjusted output accuracy.
Figure 5. +5V
+INPUT
–INPUT
+INPUT
–INPUT
+INPUT
–INPUT
Figure 3. +5V
Figure 2. Driving the On/Off Control Pin
OUT
OUT
R
T
Trim Down Connections Using A Fixed Resistor
DOWN
V
R
Trim Up Connections Using A Fixed Resistor
+3.3V OUTPUT
+3.3V OUTPUT
+3.3V OUTPUT
OUT
T
O
3
5
2
UP
+5V OUTPUT
+5V OUTPUT
+5V OUTPUT
= desired output voltage.
(k ) =
(k ) =
Trim Connections Using A Trim Pot
+INPUT
ON/OFF
CONTROL
OUTPUT
RETURN
OUTPUT
RETURN
OUTPUT
RETURN
–INPUT
TRIM
TRIM
TRIM
2.49(V
5 – V
V
6.30
O
– 5
O
10
10
10
7
8
9
7
8
9
7
8
9
O
+10V
– 2.53)
R
TRIM DOWN
R
TRIM UP
10k
–16.2
–16.2
20k
5-22
Turns
+3.3V LOAD
+3.3V LOAD
+3.3V LOAD
+5V LOAD
+5V LOAD
+5V LOAD