Voltage and current control

SEA05

6/10

Doc ID 17014 Rev 1

6

Voltage and current control

6.1

Voltage control

The voltage loop is controlled via a first transconductance operational amplifier, the voltage

divider R1, R2, and the optocoupler which is directly connected to the output. Its possible to

choose the values of R1 and R2 resistors using Equation 1-2:

Equation 1

Equation 2

where Vo is the desired output voltage.

As an example, with R1 = 100 k

Ω and R2 = 15 kΩ Vo = 19.17 V

6.2

Current control

The current loop is controlled via the second trans-conductance operational amplifier, the

Equation 3

Equation 4

control loop.

(Plim) through it during full load operation.

Equation 5

Therefore, for most adaptor and battery charger applications, it is suitable a low power

resistor to make the current sensing function.

2

2

1

o

R

)

R

R

(

Vctrl

V

+

∗

=

Vctrl

)

Vctrl

V

(

R

R

O

2

1

−

∗

=

Vcsth

I

R

max

o

sense

=

∗

max

o

sense

I

Vcsth

R

=

P

Lim

V

csth

l

omax

⋅

=