Peak current control with PWM and constant off-time

AN4158

18/34

DocID023635 Rev 2

Equation 8

When the current drop

longer be satisfied and the current control fails. The current starts to increase until stability is

restored (it is possible because

current is different than the target one. The minimum on-time limit is usually reached at low

during the off-time.

Figure 13. Peak current control unstable

Figure 12. Minimum on-time

V

Ph

I

sense

I

Ph

Reference current

t

comm

I

PhON,Min

AM15114v1

I

Ph





t

OFF

t

OFF

I

Target

t

comm

t

OFF

t

comm

t

OFF

t

comm

t

OFF

t

comm

t

OFF

t

comm

I

PhONMin

Δ

Δ

AM15115v1