SEA05 Datasheet, PDF (7/10 Pages) STMicroelectronics – Advanced constant voltage and constant current controller

SEA05
Compensation
V_csth threshold is achieved internally by a voltage divider tied to an internal voltage
reference. Its middle point is tied to the positive input of the current control operational
amplifier, and its foot has to be connected to lower potential point of the sense resistor as
shown in Figure 4. The resistors of this voltage divider are matched to provide the best
possible precision. The current sinking outputs of the two trans-conductance operational
amplifiers are common (to the output of the IC). This makes an ORing function which
ensures that whenever the current or the voltage reaches too high values, the optocoupler is
activated.
The relation between the controlled current and the controlled output voltage can be
described with a square characteristic as shown in the following V/I output-power graph.
(with power supply of the device independent from the output voltage)
Figure 5. Output voltage versus output current
Vo
Voltage regulation
Current regulation
(Vcc of the device independent from output voltage) ^Io
7
Compensation
The voltage control trans-conductance operational amplifier can be fully compensated. Both
of its output and negative input are directly accessible for external compensation
components as shown in Figure 4.
Doc ID 17014 Rev 1
7/10