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(5) Example showing use of PGM
V
SSR :3 to 6V
Z : 260Ω ±5%
V
D : 0.8 to 1.3V
• Io required in connecting one PGM
As shown in the figure below, a constant current system is employed in the
voltage output of the DCP551. The input voltage range of the PGM is as
follows.
"8.9mA≤I≤17.2mA" can be established:
I
MIN X ZMIN +VD/MIN > 3
I
MIN> 8.9mA
I
MAX X ZMAX +VD/MAX < 6
IMAX< 17.2mA
• Each PGM requires 8.9mA; the maximum output current of the DCP551 is
22mA. Thus two PGMs can be connected in parallel.
When connected in series, the maximum output current of the DCP551 is
22mA, the allowable load resistance is 600Ω and the maximum voltage that can
be applied to a load is 13.2V (22mA X 600Ω). When 8.9mA is applied to a
PGM, the maximum voltage of the input terminals end-to-end is 3.7V.
0.0089 X 260 X 1.05 + 1.3 = 3.7V
Since 13.2 ÷ 3.7 = 3.5, three PGMs can be connected in series.
The calculation above is a “worst case scenario.” For example, assuming that
3V or more is applied to each PGM, four PGMs should operate normally.
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