BOPHV020411
3-19
FIGURE 3-22. PROGRAMMING CIRCUIT FOR DRIVING THE BOP OUTPUT CURRENT WITH A
HIGH IMPEDANCE SOURCE
3.4.2
REMOTE CONTROL OF THE BOP CURRENT LIMIT
The BOP I
O
LIMIT CIRCUIT in the local (front panel) control mode is shown in FIG. 3-23. A (+)
10 volt reference voltage is repeated and inverted to obtain two reference voltages (+10V and -
10V respectively). These references are applied at the input of the two (±) I
O
LIMIT CONTROL
AMPS. Both control amplifiers operate in the inverting configuration and produce the control
potential according to the output equation:
Since “Rf” is adjustable, the control voltage (E
CONTROL
) can be varied from zero to (+)10V and
(-)10V respectively, thus providing output current limit control over the full range of the BOP
Econtrol = (–)
Eref
Ri
----------- Rf
