DIO6905

www.dioo.com

© 2023 DIOO MICROCIRCUITS CO., LTD

DIO6905 • Rev. 1.8

- 8 -

Typical Application

Detailed Description

The DIO6905 uses constant on-time control with input voltage feed-forward to stabilize the switching frequency

over its full input voltage range. It achieves 2 A of output current from a 2.3 V to 5.5 V input voltage range with

excellent load and line regulation. The output voltage can be regulated as low as 0.6 V.

Constant-on-time control

When compared to fixed-frequency PWM control, COT control offers a simpler control loop and faster transient

response. By using input voltage feed-forward, the DIO6905 maintains a nearly constant switching frequency

across the input and output voltage ranges. The switching pulse on-time can be estimated with Equation (1):

μs

0.606

*

V

V

=

tON

IN

OUT

(1)

To prevent inductor current runaway during the load transient, the DIO6905 has a fixed minimum-off-time of

60 ns.

Sleep mode operation

The DIO6905 adopts sleep mode to achieve high efficiency under extremely light load condition. In such sleep

mode, most of the circuitry is turned off, except the EA (error amplifier) and the PWM comparator, which results

in minimum operation current as shown in Figure 16.

When the loading gets lighter, and the ripple of the output voltage is bigger, the DIO6905 enters sleep mode.

Under sleep mode situation, the valley of the FB pin voltage is regulated to the internal reference voltage.

Therefore, the average output voltage is slightly higher than the output voltage in DCM or CCM. The on-time

pulse in sleep mode is around 40% larger than that in DCM or CCM mode. Figure 17 shows the average FB pin

voltage relationship with the internal reference in sleep mode.