AP2200B datasheet(7/16 Pages) AKM

7 / 16 page

[AP2200B]

MS1613-E-01

2014/04

- 7 -

10. Functional Descriptions

■ Operation Overview

When the output voltage is input to the VIN pin from the solar cell(s), the low voltage startup circuit starts to

step up the output voltage (VVOUT). When VVOUT reaches the voltage required operating the step-up

converter, the low voltage startup circuit stops operation and the step-up converter starts operation.

The input voltage is regulated to reach VVINMPP.

After that, the step-up converter increases VVOUT to the target voltage (VTGT) and controls VVOUT so that it

will be stabilized at VTGT. The step-up converter also decreases the LC pin voltage to a low level when VVOUT

reaches VTGT. For the application where an external PMOS load switch is connected to the LC pin of the

AP2200B, the external switch is turned ON to start power supply by the LC pin = “L”. However, if a one of

conditions below is met, the external load switch will be turned OFF to stop power supply.

Table 1. Stop power supply

The STBY pin is set to a high level:

The AP2200B has a standby function. When the

STBY pin is set to a high level (VIHSTB), the

external load switch is turned OFF to stop power

supply. In this case, the step-up converter is still

running even in a standby state. When the STBY

pin is set to a low level (VILSTB), the standby mode

is released and the power supply is resumed.

The VB pin voltage is less than or equal to VBLOW:

The AP2200B has a battery monitoring function.

When the VB pin voltage decrease to VBLOW or

lower, it is assumed that the battery is removed,

and the external load switch is turned OFF to stop

power supply. When the VB pin voltage increases

to VBLOW or higher, it is assumed that the battery

is reinserted, and the external load switch is turned

ON to start power supply.

To disable this function, connect the VB pin to the

VOUT pin.

The VOUT pin voltage is less than or equal to VOL:

When the VOUT pin voltage decreases to VOL and

lower, the external load switch is turned OFF to

stop power supply. In this case, the step-up

converter is still running. When VVOUT reaches

VTGT again, the power supply is resumed.

Every tPV Period (solar condition checking):

The AP2200B turns OFF the external load switch

as well as stopping the voltage step-up operation

by each tPV period. The voltage step-up operation

is resumed after a certain period of time. However,

unless VVOUT reaches VTGT again, the external

load switch is not turned ON.

This prevents back flow from the battery to

VVOUT to minimize the battery consumption

when the power supply from the solar cell(s)

decreases and the step-up converter cannot increase

the voltage sufficiently.

AP2200B Datasheet(PDF) 7 Page - Asahi Kasei Microsystems

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