Detailed description

STODD01

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Doc ID 17789 Rev 2

7

Detailed description

7.1

Brief overview

The STODD01 is a complete high efficiency switching power management. Inside it has a

step-up converter with a current capability up to 0.7 A and two step-down converters with a

current capability up to 0.8 A.

The controller uses an average current mode technique in order to obtain good stability in all

application conditions.

The step-up converter, in order to guarantee the lowest switching ripple, operates in PWM

(pulse width modulation) in all load conditions.

Both step-down converters, in order to maintain good efficiency, operate in power-save

mode at light load. When the load increases, they automatically switch to PWM (pulse width

modulation) mode and the output voltage ripple is minimized.

The STODD01 is self protected against overtemperature and accidental short circuit in the

step down channel.

The soft-start function guarantees proper operation during startup.

7.2

Enable pin

The step-up section operates when the EN pin is set high. If the EN pin is set low the step-

up turns OFF. In this condition the supply current is lower than 2 mA in the whole

temperature range, and it represents the consumption of the step-down section.

When the EN pin is low, thanks to at the true cut-off function, implemented using two P-

channel MOSFETs in a back-to-back configuration, as shown in Figure 10, the output

current is stopped. In order to control and reduce the in-rush current, the true cut-off P-

Figure 10.

True cut-off block

SW1

PGND

Ps

OUT1

Po

Ns

SW1

PGND

Ps

OUT1

Po

Ns