roal RCB1200, User Manual, Page: 15 / 33

15
Remote Voltage Programming (External voltage control)
The output voltage of the module can be adjusted using an external voltage source connected between the COM and V
control
pins on the signals connector (J5) as shown below.
In this configuration the output voltage will follow the equation below,
V
o
= V
set
((1.8 - V
ctrl
) / 0.6), where V
set
is the manual preset voltage of the module.
The output voltage can be controlled from 0% to 300% of the preset voltage using this control method. However, care must
be taken to ensure the output voltage does not exceeed the OVP level, as this is considered a safety hazzard and will latch the
correspondent section off.
To determine the level of control voltage that will trigger OVP, insert V
OVP
into the equation above.
Example: V
OVP
= 9.5 V, V
set
= 5 V; V
ctrl
= 1.8-(V
OVP
*0.6/V
set
) = 0.66 V
Hence, V
ctrl
should never fall below 0.66 V, otherwise OVP may latch the entire unit off.
Alternatively, by manually adjusting the output voltage to less than 1/3
rd
of the OVP voltage ensures that OVP can never be
tripped by remote voltage control.
Care must be also taken to ensure that the output voltage would not be forced below the V
MIN
limit, which is stated for each of
the output modules (OP-A, OP-B, OP-C and OP-D) in the data-sheet. Exceeding in the output voltage adjustment below the
minimum limit, means to force the module output stage to operate in electric overstress, leading to a possible damage more
likely the higher the output current required by the load.
Similarly to the above, the control voltage which correspond to the V
MIN
level of the output voltage is:
V
MIN
= V
set
((1.8 – V
ctrl
) / 0.6; V
ctrl
= 1.8 – (V
MIN
*0.6) / V
set
Example: V
MIN
= 1.5, Vset = 5 V; Vctrl should not be higher then 1.62 V
Also, remote adjustment of the output voltage using the V
control
pin does not affect the preset power good threshold. Hence,
remotely adjusting the output voltage below 0.9*V
set
will cause the power good signal to go low.
A
DVANCED
O
UTPUT
M
ODULE
F
EATURES
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