DA6011B.001
18 October, 2011
MAS6011B
Solar Cell Energy Harvesting
System Manager
VDD
MAS6011
XPD
LB
•
•
•
•
Ultra Low Power, 110nA
Low Battery Indicator
Precise Power Up/Down
Battery Overcharging
Protection
SW
SOL
GND
DESCRIPTION
The MAS6011 solar cell system manager monitors
the supply voltage and charging of a battery-
powered system containing a small solar cell. The
current consumption of this IC is extremely low, 110
nA, which means the system can charge from very
low light conditions and also stay in power down
mode for years and still operate directly from the
battery before recharging.
To be able to charge a battery also in condition with
very limited light, a large solar cell is usually used.
This can on the other hand easily destroy the
battery due to over voltage during strong sun light.
MAS6011 solves this dilemma and will give secure
protection of a secondary 3V battery over a big
range of light strengths (lx).
Three output signals indicate the state of the
system. Power Down (XPD) indicates whether the
supply voltage is high enough to power up and run
the system. Low Battery (LB) is used to signal the
condition when the battery capacity is low and
when to move to power saving mode. The third
signal, SOL, is used for battery charging control.
When the battery is full it bypasses the charging
current by an internal shunt switch to avoid
overcharging. The SW pin can also be used to
control an external shunt switch for higher currents.
FEATURES
•
•
•
•
•
•
•
Ultra Low Current Consumption, typ 110nA
Low Supply Voltage Operation, min 2.0V
Battery Overcharging Protection
Power On Indicator and secure Power ON after
shut down
Deep discharge protection of battery during
shut down mode
Precise Shut Down and precise Low Battery
warning threshold levels
Suitable for rechargeable 3V Lithium Vanadium
Pentoxide (VL-type) batteries
APPLICATIONS
•
•
•
•
•
•
•
Solar Powered Watch
Solar Powered Wireless Sensor
Solar Powered Devices with Back-Up
GPS Modules
Time Code Receiver modules
Electronic locks
Energy Harvesting
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DA6011B.001
18 October, 2011
FUNCTIONAL DESCRIPTION
The solar manager generates three main signals:
XPD (Power Down), LB (Low Battery) and SOL
(Solar Charging). The fourth SW signal is for
controlling an optional external PMOS transistor.
These signals are produced by three comparators
which have hysteresis build in. Each comparator
compares the supply voltage (VDD) to the internal
switching levels. The current consumption of the
comparators is extremely low. The electrical
parameters are described more detailed in the
Electrical Characteristics chapter.
The XPD signal can be used to power down the
whole system whenever the supply voltage level
has dropped too low (see application figure 4).
When the supply voltage is too low the XPD goes
low to power down the solar powered system.
When the supply voltage is high enough the XPD
goes high controlling power up condition.
For a low power system (max current consumption
1mA) the XPD pin output can be used as a system
supply voltage (see application figure 5) to keep the
systems current consumption to a minimum.
The LB signal indicates that the battery is low but
not empty. It can be used to control the system into
a power saving mode. In power on (XPD=high) LB
goes high when supply voltage level is too low and
LB goes low when supply voltage level is high
enough. In power down (XPD=low) the LB is low.
SOL is used for controlling the charging of the
rechargeable battery. Normally the internal PMOS
switch between VDD and the SOL pin is non-
conductive but when the power supply voltage rises
too much this switch is switched on to shunt the
solar cell charging current and to prevent battery
overcharging. The maximum shunt current
capability of the internal PMOS switch is typically
28 mA. If a larger shunt current is needed an
external PMOS transistor can be used controlled by
the SW pin (see application figure 6).
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 NPN transistor.
MAS6011 does not have any control pin. After the
power supply is connected the device is ready to be
used.
The XPD, LB and SOL/SW switching levels have
been designed for usage with VL-type rechargeable
lithium vanadium pentoxide batteries.
Those
batteries are compact, high energy secondary
batteries that have nearly twice the energy of
conventional button-shaped Ni-Cd batteries. The
self discharge rate is less than 2% a year which
makes them very useful as a power source in
systems that might be stored for a long time without
re-charging.
Figure 1 illustrates the MAS6011 functions and
shows the comparator switching levels for both
battery charging (rising VDD) and discharging
(falling VDD) conditions.
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DA6011B.001
18 October, 2011
ABSOLUTE MAXIMUM RATINGS
All voltages with respect to ground.
Parameter
Supply Voltage
Voltage range for all pins
Operating temperature
Storage Temperature
Symbol
VDD
T
A
T
S
Conditions
Min
-0.3
-0.3
-40
-50
Max
5.5
VDD+0.3
+85
+125
Unit
V
V
o
C
o
C
Stresses beyond those listed may cause permanent damage to the device. The device may not operate under these conditions, but it will
not be destroyed.
This is a CMOS device and therefore it should be handled carefully to avoid any damage by electrostatic voltages (ESD). The most sensitive
pin for the ESD is the SOL pin.
ELECTRICAL CHARACTERISTICS: MAS6011BA1 (3V BATTERY, MCU VDD
min
≤
2.1V)
Operating Conditions: T
A
= -40°C to +85°C, typical values at T
A
= +27°C, unless otherwise specified.
Parameter
Supply voltage
Current consumption
Symbol
VDD
I
DD
Conditions
Min
2.0
Typ
3.0
85
110
130
2.60
2.30
300
2.0
Max
3.6
160
200
230
2.80
2.50
600
Unit
V
nA
XPD switching level
XPD hysteresis
XPD output voltage
LB switching level
LB hysteresis
LB output voltage
SOL switching level
SOL hysteresis
SOL sink current
SOL leakage current
LB_OFF – XPD_OFF
LB_ON – XPD_ON
SOL_OFF – LB_OFF
SOL_ON – LB_ON
TBD = To be defined
XPD_OFF
XPD_ON
V
XPD(H)
V
XPD(OUT)
LB_OFF
LB_ON
V
LB(H)
V
LB(OUT)
SOL_OFF
SOL_ON
V
SOL(H)
I
SOL
VDD=2V
VDD=3V
VDD=3.5V
Power Down Off (XPD high)
Power Down On (XPD low)
VDD = 2.1 V,
I
XPD
= -1mA
Low Battery Off (LB low)
Low Battery On (LB high)
LB high, I
LB
= -50 µA
LB low, I
LB
= +50 µA
Solar Charging Off
Solar Charging On
VDD = 3.6 V, SOL = 0 V,
SOL switch On
VDD = 2.9 V
30
50
60
2.40
2.10
180
V
mV
V
2.55
2.35
100
VDD-0.05
3.02
2.90
50
19
-50
10
100
200
350
2.70
2.50
200
2.85
2.65
400
0.05
3.55
3.40
300
43
50
V
mV
V
3.30
3.15
150
28
V
mV
mA
nA
mV
mV
mV
mV
V
LB_XPD_OFF
V
LB_XPD ON
V
SOL_LB_OFF
V
SOL_LB ON
100
200
600
650
200
300
800
949
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