AS1301 datasheet(10/16 Pages) AMSCO

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AS1301

Data Sheet - Deta iled Description

Switch Configuration

The AS1301 has nine built-in power switches in the shape of two coupled H-bridge topologies. The system features

1:2 and 2:3 operation modes as well as a 1:1 operation where the input is directly connected to the output. This

feedthrough mode is suitable for input voltages higher than the output voltage.

In 2:3 operation mode two flying capacitors are placed in series and each capacitor is charged to a half of the input

voltage. In pumping phase the flying capacitors are placed in parallel. The bottom-plates of the parallel flying

capacitors CFLY1 and CFLY2 are then connected to the input voltage so that the voltage at the top-plates of the flying

capacitors is boosted to a voltage equal to VBATT + VBATT/2. By connecting the top-plates of the capacitors to the

output, the output voltage in 2:3 mode can be up to one and a half of VBATT. If the top-plate voltage is higher than 5V,

the regulation loop adapts the power transistor’s current drive capability to drop some voltage. The 2:3 operation mode

runs in single-phase operation only.

In 1:2 operation mode just one of both flying capacitors is placed in series to the input voltage, and therefore charged

to the input voltage. During pumping phase the input voltage is connected to the bottom-plate of the discharged flying

capacitor CFLY. The voltage at the top-plate of the capacitor is now boosted to 2VBATT. By connecting the top-plate of

the capacitor to the output, the output can be charged to twice the voltage of VBATT. If the top-plate voltage is higher

than 5V the regulation loop limits the charge transfer to the output. In collaboration with the second flying capacitor this

mode features dual-phase operation.

Figure 27. 2:3 Operating Mode

VBATT

SW1

CFLY1

CFLY2

SW3

SW2

SW4

Charging Phase

VOUT

VBATT

SW1

CFLY1

CFLY2

SW3

SW2

SW4

Pumping Phase

VOUT

Figure 28. 1:2 Operating Mode

VBATT

SW1

CFLY1

CFLY2

SW3

SW2

SW4

VOUT

SW1

CFLY1

CFLY2

SW3

SW2

SW4

VOUT

Charging Phase

Pumping Phase

VBATT

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