www.ams.com/DC-DC_Step-Up

Revision 1.12

8 - 20

AS1312

Datasheet - D e t a i l e d D e s c r i p t i o n

Figure 10. Simplified Voltage and Current Waveforms

Another important relationship is the “volt-seconds” law. Expressed as following:

(EQ 4)

Voltages are those measured across the inductor during each time segment. Figure 10 shows this graphically with the shaded segments marked

“A & B”. Re-arranging (EQ 4):

(EQ 5)

8.1.2

Inductor Choice Example

Let the maximum operating on-time = 1µs.

T

T

0

0

SW1_on

SW2_off

SW1_off

SW2_on

V

T

C

B

B

A

T

C

D

D

V

V

=

T

O N

T

O FF

-------------

V

O UT

V

IN

–

V

IN

----------------------------

=