DA9011.001

28 Jan 2004

3 (9)

FUNCTIONAL DESCRIPTION

The solar manager generates three signals: PO

(Power On), LB (Low Battery) and SOL (Full

Battery).

These signals are produced by three comparators

which have hysteresis build in. Each comparator

compares supply voltage (VDD) to

internal

switching levels (see Electrical Characteristics on

next page). The current consumption of the

comparators is very low. The electrical parameters

are described more detailed in the Electrical

Characteristics chapter.

PO signal can be used to stop the whole system

whenever the power supply level has dropped low

enough. When power supply voltage is too low, the

PO

goes

high

to

give

signal

to

watch

microcontroller to go power down.

LB signal indicates that the battery is low but not

empty. LB goes high when power supply level is too

low.

SOL is used for battery charging control of the solar

watch. When power supply voltage goes high

enough, the internal PMOS switch between VDD

and SOL pins is switched on to shunt the solar cell

charging

current

and

to

prevent

battery

overcharging.

In operation without an external Schottky diode

between the pins SOL and GND, the voltage at pin

SOL is clamped to about 700 mV below GND by a

diode-connected PNP transistor.

MAS9011 does not have any control pin. After the

power supply is connected the device is ready to be

used.