DA6011.000

15 September 2008

3 (8)

FUNCTIONAL DESCRIPTION

The solar manager generates three signals: XPD

(Power Down), LB (Low Battery) and SOL (Solar

Charging).

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 the next

page). The current consumption of the comparators

is extremely low. The electrical parameters are

described

more

detailed

in

the

Electrical

Characteristics chapter.

XPD signal can be used to stop the whole system

whenever the power supply level has dropped low

enough. When the power supply voltage is too low

the XPD goes low to signal the microcontroller to go

to power down. When the power supply voltage is

high enough the XPD goes high signaling power up

situation.

In case of low power microcontroller (max current

consumption about 150 µA) the XPD pin can be

used

to

feed

supply voltage

directly to

the

microcontroller by connecting XPD pin to the supply

voltage pin of the microcontroller (see application

figure 3).

LB signal indicates that the battery is low but not

empty. LB goes high when power supply level is too

low and LB goes low when power supply level is

high enough.

SOL is used for controlling the charging of the

rechargeable battery. 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. When the power supply voltage is not

too

high

the

internal

PMOS

switch

is

non-

conductive.

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 an

internal diode-connected PNP transistor.

MAS6011 does not have any control pin. After the

power supply is connected the device is ready to be

used.

Figure 1 illustrates MAS6011 functions and shows

the comparator switching levels at both battery

charging (rising VDD) and discharging (falling VDD)

conditions. The XPD, LB and SOL switching levels

have

been

designed

for

usage

of

VL-type

rechargeable lithium batteries.

2.0V

2.5V

3.0V

3.2V

3.1V

2.7V

2.9V

2.8V

2.6V

2.2V

2.4V

2.3V

2.1V

3.3V

VDD

SOL_OFF (charging off)

SOL_ON (charging on)

LB_OFF (low battery off)

LB_ON

(low battery on)

XPD_OFF (power down off)

XPD_ON

(power down on)

BATTERY CHARGING

(VDD RISING)

BATTERY DISCHARGING

(VDD FALLING)

Figure 1. MAS6011 functions