BXA15 ARTESYN [Artesyn Technologies], BXA15 Datasheet - Page 2

• Manufacturer Part Number: BXA15
• Description: Design Note 100 Rev. 01 - Feb. 1999
• Manufacturer: ARTESYN [Artesyn Technologies]

Remote Sense:
The remote sense feature automatically adjusts the output voltage
of the dc/dc converter to compensate for line voltage drops to loads
which are distant form the output pins. Internally, 150R, 0.25Watt
resistors connect the sense circuitry to the output pins. In applica-
tions, the sense connections must be made. These can either be
made directly at the pins whereby compensation for voltage line
drops is not needed.
Or the connection can be made at the load or point of critical regu-
lation. If the sense connections are not made the output voltage will
typically be up 7% on nominal and load regulation will be substan-
tially degraded.
Voltage Drops on the lines to the load may be compensated up to a
maximum value of 10%. This includes any voltage increase that
may result by use of the ‘TRIM’ function. If the output voltage is
raised above the nominal value +10%, the unit performance at low
input voltage may be degraded.
Ensure the load power lines are never open circuit in a remote sense
application. Even transient open circuits in the power connections
could result in full load current flow through the sense leads, result-
ing in damage to the internal circuitry.
The usual rules for remote sensing apply:
a) The remote sense tracks should be parallel and close to each
Output Voltage Trim:
Output voltage trim enables the user to adjust the output voltage to
a pre-defined value within ±10% of the nominal output voltage.
5. System Protection Features
Overvoltage Protection:
Internally, a 400Watt/1ms semiconductor transient voltage suppres-
sor has been inserted across each output voltage. This is designed
to protect both the BXA15/BXA30 and the customer’s load from
transient overvoltages induced or reflected by the load. This feature
is not intended to guarantee steady state overvoltage protection.
6. Thermal Considerations
Maximum Operating Temperatures:
The BXA15 and BXA30 baseplate must never be allowed to exceed
100°C. The maximum operating ambient temperature depends on
the ambient airflow, the ambient temperature, the unit mounting/ori-
entation and the power dissipated by the unit. In application, the
worst case operating baseplate temperature should be measured.
b) Remote sensing provides DC regulation at the sense points but
other. Alternatively screened cable could be used. This minimises
inductive noise pick-up and reduces 2 pole roll-off effects in the
feedback loop.
AC regulation is degraded. To maintain best possible transient
response performance, a decoupling capacitor should be used at
point of sensing. A capacitance value >10uF/Amp is recommend-
ed.
Output
3.3V
12V
15V
5V
OVP Value
3.9V breakdown init.
6.7V breakdown init.
15.6V breakdown init.
18.9V breakdown init.
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BXA15 AND BXA30 SERIES
As an example, for the BXA15 and BXA30 with the baseplate
mounted vertically, in free natural convection:
For a BXA15 and BXA30 with baseplate and heatsink mounted ver-
tically, in free natural convection:
For operation at output powers > 50% nominal max. and with input
voltages within 30% of nominal, the operating efficiency is approxi-
mately = the specified nominal efficiency:
These formulae calculate deratings necessary at high operating tem-
peratures. An optional heatsink is available to increase output power
at high ambient temperatures.
Minimum Operating Temperature:
All qualification and design testing were conducted with baseplates
ranging from -25°C to +100°C.
Short Circuit Ratings:
The product is indefinitely short-circuit rated. The baseplate should
be maintained at less than 100°C. Under a short circuit, the typical
power dissipation is 7 Watts. This may be up to 10 Watts at maxi-
mum input voltage.
Short Circuit Protection on Multiple Output Units:
With the exception of the BXA15-48D05 and BXA30-48D05, all of
the multiple output units have short circuit protection as outlined
above. For details on the two exception models, please consult the
factory.
Cross Regulation Dual Output Models:
Internally the absolute value sum of the output voltages is regulated.
The total output on a 48D05 will be regulated to be 10 volts.
These figures are typical for all dual models.
Remote ON/OFF:
Internally this is connected to a bipolar Vbe + 2 Si diodes in series.
The pin is connected to -Vin, via a 15K resistor. This provides noise
immunity. An open collector sink (maximum current 3mA) to a volt-
age <1Volt is required. The open circuit voltage will be 3 Volts.
Transient Response:
For best output voltage response to load transients; a minimum out-
put load of 5% is recommended. On 12 Volt (input) models, the
input voltage should be maintained >9.5 Volts for optimum transient
response.
Input Impedance Considerations:
Care needs to be taken to ensure the source impedance is suffi-
ciently low to allow correct operation of the DC/DC over all operat-
ing conditions; particularly for power-ups and load transients.
(Pdiss. MAX. * Rth B.P - AMB. ) + T AMBIENT.MAX. ≤100°C.
Number
Model
48D05
Pdiss. = Pout (100 - h) /h
|
Rth (B.P.+H.S.) - AMB. = 5.2°/Watt.
Regulation %
Design Note 100 Rev. 01
Rth B.P - AMB. = 6.5°/Watt.
Cross
2.5%
4%
7%
h = Operating Efficiency %.
Load One
Output
100%
100%
100%
Load Other
Output
PAGE 2
40%
10%
0%