Casio IT-2000W manual Battery Voltage Monitoring Process, Battery Operation Scheme

2.2.4Battery Voltage Monitoring Process

This terminal uses a main battery (lithium-ion battery pack) for driving the main unit, and a primary sub-battery (lithium battery) and a secondary sub-battery (lithium-vanadium battery) for backup. Application programs can acquire the status of these batteries through the APM BIOS or system library. Refer to Chapter 9.5 “Remaining Battery Voltage Display Utility”.

Battery Operation Scheme

The following diagram shows how each battery operates within the system.

Monitors

primary

sub-battery

voltage.

(LB2)

Main battery

Monitors main battery

voltage (LB1￿LB0)

Sub-battery

[A]

Charge

[A]

[A](During ON)

(During ON)

SRAM Card

Primary

Secondary sub-battery

Monitors

sub-battery

(Rechargeable)

SRAM card

[A]

voltage. (LB3)

[C]

[B]

PC Card Slot

Objective devices of backup

Main circuit

(DRAM, etc.)

(CPU and controllers, etc.)

Fig. 2.5

[A]This is the power supply route where the fully charged main battery is installed.

While the power is on, the main battery supplies power to all the devices, including the main circuit, PC card slot and DRAM, and, at the same time, it charges the secondary sub-battery.

In the suspend state, it stops the supply of power to the main circuit and PC card, but continues to supply power to the DRAM and charge the secondary sub-battery. In this route neither the primary nor the secondary sub-batteries are used.

[B]This is a power supply route operating where the main battery is absent or not fully charged. The DRAM is back-upped by the voltage of the secondary sub-battery. The primary sub-battery is not used.

[C]This power supply route operates if the main battery and secondary sub-batteries are not fully charged. The DRAM is backed-up by the voltage of the primary sub-battery. If the voltage of this primary sub-battery falls below the limit level, an LB2 event occurs.

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