STBB2 Datasheet, PDF (16/25 Pages) STMicroelectronics – 800 mA 2.5 MHz, high efficiency dual mode buck-boost DC-DC converter

General description
STBB2
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.
Table 8. Bypass and enable matrix
EN
BP
MODE
Status
0
0
0
Shutdown
0
0
0
1
1
Shutdown
0
Shutdown
0
1
1
Shutdown
1
0
0
Auto mode
1
0
1
PWM mode
1
1
0
Bypass
1
1
1
Bypass
7.4
VSEL pin operation
For the fixed output voltage version, the FB pin must be connected to the V_OUT pin. Fixed
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
connected to V_INA.
P/N
STBB2J-29
STBB2J-30
Table 9. Output selection
V_SEL
Low
High
Low
High
V_OUT
2.9 V
3.4 V
3.0 V
3.3 V
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DocID022745 Rev 9