LSO2805S Datasheet, PDF (10/18 Pages) International Rectifier – HYBRID-HIGH RELIABILITY RADIATION HARDENED DC-DC CONVERTER

LSO SERIES
28V Input, Single/Dual Output
Output Voltage Adjustment:
Output of LSO singles and duals can be adjusted to be
greater or less the nominal output voltage with an external
resistor. However, the ranges of the output voltages are
limited depending on the model as specified in Table 1 and
Table 2. An approximate value of the resistor can be
determined using the following formula.
For Single Output Model:
Radj = ^{A - (B * V out )}
(C _* Vout ) - D
For Dual Output Model:
Radj = ^{A - (B * 2 * Vout )}
(C _* 2 _* Vout ) - D
Where:
Radj is the external resistor in ohms, as shown in Fig 7.
Power rating of the resistor shall be ≥ 0.125 W. Metal film
resistor with temperature coefficient of ≤ ± 50 ppm and
tolerance of ≤ 1% is recommended. However, the final
selection is dependent on specific design requirements.
Vovp is the output voltage in volts.
A, B, C and D are unique constants depending on every
model as shown in Table 1 for single output models and
Table 2 for dual output models.
Table 2. LSO2805S. Output Voltage Ranges and Constants
Constants
A
B
C
D
Output voltage
Low range
4.750 to 5.000
588.3 x10⁶
264.5 x10⁶
7950
39716
Output voltage
High range
5.000 to 5.250
587.8x10⁶
699.6 x10⁶
7950
39717
Table 3. LSO2815S. Output Voltage Ranges and Constants
Constants
A
B
C
D
Output voltage
Low range
14.250 to 15.000
588.3 x10⁶
264.5 x10⁶
7950
39716
Output voltage
High range
15.000 to 15.750
1451.2x10⁶
57.5 x10⁶
6540
39717
Table 4. LSO2805D. Output Voltage Ranges and Constants
Constants
A
B
C
D
Output voltage
Low range
r4.750 to r5.000
1012.4x10⁶
395.0x10⁶
6840
68344
Output voltage
High range
r5.000 to r5.250
1011.5x10⁶
60.1x10⁶
6840
68344
Table 5. LSO2815D. Output Voltage Ranges and Constants
Constants
A
B
C
D
Output voltage
Low range
r14.250 to r15.000
2780.2x10⁶
974.8x10⁶
6260
187646
Output voltage
High range
r15.000 to r15.750
2777.9x10⁶
55.0x10⁶
6260
187646
Placement of Radj: An external resistor must be added
in order to trim the output voltage of a LSO converter.
The placement of a Radj resistor must be connected as
shown in Fig. 7.
Singles: Radj is placed across Out Adj and ± Sense
pins. For output voltage greater than nominal voltage,
Radj is placed from Out Adj to –Sense. To have output
voltage less than nominal voltage, place Radj across Out
Adj and +Sense.
Duals: Radj is placed across Out Adj and ± Output pins
respectively.
Table 1. LSO2803R3S. Output Voltage Ranges and Constants
Constants
A
B
C
D
Output voltage
Low range
3.135 to 3.300
466.4 x10⁶
238.3 x10⁶
9550
31489
Output voltage
High range
3.300 to 3.465
466.0x10⁶
84.0 x10⁶
9550
31489
Fig. 7 - Output Voltage Adjustment
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