LSO2805S Datasheet, PDF (11/18 Pages) International Rectifier – HYBRID-HIGH RELIABILITY RADIATION HARDENED DC-DC CONVERTER

LSO SERIES
28V Input, Single/Dual Output
OVP External Adjustment:
Over-voltage Protection threshold of LSO singles and
duals can be adjusted to be greater or less the nominal
OVP with a couple of external resistors. Lower resistors,
R1 and R2 are 10KΩ resistors, while Radj set the new
OVP threshold as stated in Table 6 for single output
models and Table 7 for dual output models. Ranges of
LSO series converter can be adjusted from 115% to
125% of the nominal output voltage. See Fig.8 to place
external resistors.
An approximate value of the resistor can be determined
using the following formula.
Radj
=
(A _* Vovp ) - B
C - (D _* Vovp)
Where:
Radj is the upper external resistor in kilo-ohms, as shown
in Fig 8. 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 protection limit in volts.
Table 7. LSO Duals. OVP Exeternal
Range
Vo* (115%)
Vo* (116%)
Vo* (117%)
Vo* (118%)
Vo* (119%)
Vo* (120%)
Vo* (121%)
Vo* (122%)
Vo* (123%)
Vo* (124%)
Vo* (125%)
LSO2805DS
OVP
5.75
5.80
5.85
5.90
5.95
6.00
6.05
6.10
6.15
6.20
6.25
Radj
(KΩ)
26
28
30
33
36
39
43
47
51
57
64
LSO2815D
OVP
17.25
Radj
(KΩ)
101
17.40 107
17.55 113
17.70 121
17.85 128
18.00 137
18.15 146
18.30 157
18.45 169
18.60 183
18.75 199
Fig. 8 - OVP with External Adjustment
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A, B, C and D are unique constants depending on every
model.
Placement of Radj: Two external resistors must be
added in order to set new OVP threshold.
Singles: Radj(OVP) is placed across +Output and OVP
Adj pins and R1 from OVP Adj to -Output.
Duals: Radj(+OVP) is placed across +Output and +OVP
Adj pins and R1 from +OVP Adj to -Return. Radj(-OVP) is
placed across +Return and -OVP Adj pins while R2 is
placed across -OVP Adj to –Output.
Table 6. LSO Singles. OVP Exeternal
Range
Vo* (115%)
Vo* (116%)
Vo* (117%)
Vo* (118%)
Vo* (119%)
Vo* (120%)
Vo* (121%)
Vo* (122%)
Vo* (123%)
Vo* (124%)
Vo* (125%)
LSO2803R3S
OVP
3.79
3.82
3.86
Radj
(KΩ)
13
15
16
3.89
18
3.92
20
3.96
22
3.99
25
4.02
28
4.05
31
4.09
36
4.12
41
LSO2805S
OVP
5.75
5.80
5.85
Radj
(KΩ)
26
28
31
5.90 33
5.95 36
6.00 39
6.05 42
6.10 46
6.15 51
6.20 56
6.25 63
LSO2815S
OVP
17.25
17.40
17.55
Radj
(KΩ)
102
108
114
17.70 121
17.85 128
18.00 137
18.15 146
18.30 157
18.45 168
18.60 181
18.75 197
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Stacking Outputs:
On dual output models, output can be stacked to double
the output voltage as shown in Fig 9.
Fig. 9 - Stacked Outputs on Dual Models
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