SBB501S Datasheet, PDF (2/11 Pages) International Rectifier – HIGH RELIABILITY CLASS K HYBRID RADIATION HARDENED, NON-ISOLATED

SBB SERIES
Single Output
The product’s package footprint is less than three
square inches. The package and lid materials are
cold rolled steel. The low profile package measures
1.9"L x 1.5"W x 0.335"H, excluding mounting tabs
and input/output (I/O) pins. The ceramic sealed I/O
pins protrude the package’s side walls with the
mounting tabs on the corners of the side walls. The
I/O pins are copper Alloy 52. The pins are gold plated
for long term storage. Gold is to be removed prior to
assembly. A complete POL weighs less than 60
grams. Cooling of this device can be accomplished
by bonding the base of the package to a metal plate
or heat sink with a thermally conductive material.
The package’s mechanical outline and I/O pins
functional assignment are included in this data sheet.
The SBB POLs are designed, manufactured, tested,
and qualified at IR’s facility in San Jose, California
which is qualified to ISO9001 and MIL-PRF-38534
by DSCC. Flight hardware is 100% screened and
fully compliant to class K per MIL-PRF-38534.
Abbreviated screening version or engineering model
(EM) of the SBB is available for engineering evaluation.
Please refer to the Device Screening table for details.
Circuit Description
The SBB Series POLs utilize a non-isolated buck
circuit design topology with synchronous output
rectification to maximize efficiency. The nominal
switching frequency is 400 KHz. An internal EMI filter
minimizes the reflected switching ripple current to
meet most space applications at the system level. A
two-stage output filter reduces the output ripple and
noise to a very low level required by today’s digital
loads. No external filter capacitors are required for
typical design applications.
Output current is limited under any load fault
condition. It is designed to behave similar to a
constant current source with the output voltage
dropping below nominal. The SBB POL will resume
normal operation when the load current is reduced
below the current limit point. This protects the POL
from both overload and short circuit conditions.
The current limit threshold exhibits a negative
temperature coefficient to reduce the possibility of
thermal runaway.
Undervoltage Lockout (UVLO): An UVLO circuit
prohibits the POL from operating when the line
voltage is too low to maintain the output voltage.
The POL will not start until the line input voltage
rises to approximately 4.3 volts and will shut down
when the input voltage drops below 3.9 volts.
Output Voltage Adjustment: The output voltage
(Vout) of an SBB can be adjusted to ±10% of a
nominal output voltage. One external resistor with
a power rating of > 0.125 watt is required for this
function.
Following is the formula to determine an approximate
value of the resistor and how it needs to be
connected to the functional pins for a higher and a
lower output voltage with respect to the nominal
output voltage.
To reduce Vout, connect an adjust resistor to
Vadjust pin and Output pin
Radj
=
⎪⎪⎩⎪⎪⎨⎧^{112V820no−×mV2}_Vo^{×unVtoom−u1t0280}
⎫
⎪⎪
⎬
⎪⎪⎭
To increase Vout, connect an adjust resistor to
Vadjust pin and Output Return pin
Radj
=
⎧
⎪⎪⎨
⎪⎪⎩
9280 ×Vout _−10280
Vnom
2 − ^{2 ×Vout}
Vnom
⎫
⎪⎪⎬
⎪⎪⎭
Where:
Radjust is the value of the adjust resistor in Ohms(Ω)
Vnom is the nominal output voltage of the SBB
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