General description

STBB2

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DocID022745 Rev 9

7.3

Bypass operation

In bypass mode the output is connected directly to the battery by two P-channels and the

inductor. The bypass function has been implemented in order to save energy when the

application is in idle mode. At light load condition, the device can be in bypass mode to

reduce the current drained from the battery. In bypass mode the quiescent current is around

5 µA. Without bypass function, the buck-boost works in pulse-skipping mode with around 50

µA of current consumption. The device can be placed in bypass mode by the BYP pin.

7.4

VSEL pin operation

output voltage versions have two different output voltages programmed internally which are

selected by programming high or low at VSEL. The higher output voltage is selected by

programming VSEL high and the lower output voltage is selected by programming VSEL

low. This feature is not present in the adjustable version, where the VSEL pin must be

Table 8. Bypass and enable matrix

EN

BP

MODE

Status

00

0

Shutdown

00

1

Shutdown

01

0

Shutdown

01

1

Shutdown

1

0

0

Auto mode

10

1

PWM mode

1

1

0

Bypass

1

1

1

Bypass

Table 9. Output selection

P/N

STBB2J-29

Low

2.9 V

High

3.4 V

STBB2J-30

Low

3.0 V

High

3.3 V