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VA7205 Schematic ( PDF Datasheet ) - Vimicro

Teilenummer VA7205
Beschreibung Advanced Linear Charger IC
Hersteller Vimicro
Logo Vimicro Logo 




Gesamt 14 Seiten
VA7205 Datasheet, Funktion
VA7205_100-1.3_En
ADVANCED LINEAR CHARGER IC
For LITHIUM-ION AND LITHIUM-POLYMER Battery
FEATURES
Ideal for Single (4.2V) Li-ion or Li-Polymer
Packs
Better Than ±1% Voltage Regulation Accuracy
With Preset Voltage
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Adjustable precharge current with an external
resistor
Adjustable Charging Current During Constant
Current Charging Stage
Constant Voltage Charging
Automatic Battery-Recharge Feature
Cell-Temperature Monitoring Before and During
Charge
Dynamic compensation of Battery Pack’s
Internal Impedance to Reduce Charge Time
Charge Status Output for Dual Led
Cell Condition Monitoring
Automatic Low-Power Sleep Mode When Vcc is
Removed or When Voltage Supply is Lower
than battery voltage
Requires Small Number of External
Components
Packaging: 8-Pin SOP or MSOP
DESCRIPTION
The VA7205 series advanced Lithium-Ion (Li-Ion)
and Lithium-Polymer (Li-Pol) Linear Charger ICs
are designed for cost-sensitive and compact
portable electronics.
They combine
high-accuracy current and voltage regulation,
battery condition monitoring, temperature
monitoring, charge termination, charge-status
indication, and internal impedance compensation
in a single 8-pin IC. It is the best suitable device
to be used in the PDA, mobile phones, and other
portable devices.
The VA7205 monitors the battery charging status
by detecting the battery voltage level. The
VA7205 charges the battery in three phases:
conditioning, constant current, and constant
voltage.If the battery voltage is below the
low-voltage threshold, Vmin (normally at 3V), the
VA7205 precharges using a low current to
FUNCTION BLOCK DIAGRAM
condition the battery. The conditioning charge
rate can be adjusted with an external resistor.
After the battery is precharged to Vmin, the
VA7205 applies a constant current to the battery.
An external sense-resistor sets the current.
The constant-current phase continues until the
battery reaches the charge-regulation voltage
(normally at 4.2V) and then the VA7205 begins
the constant-voltage phase. The accuracy of the
voltage regulation is better than ±1% over the
operating-temperature and supply-voltage
ranges. Under this stage the charging current
will gradually decrease. Charge stops when the
current tapers to the charge termination
threshold, ITERM. The VA7205 will continue
monitoring the battery voltage level and entering
a new cycle of charging if the battery’s voltage
level has fell below VRECHG (normally at VREG -
125mV).
During the charging process, for the safety
concern, the VA7205 continuously measures
battery temperature using the battery’s internal
heat sensitive resistor and an external resistors.
If the temperature of the battery exceeds the
pre-set temperature range, the charging process
will come to a halt after 0.5 seconds; After the
temperature fell back into the pre-set
temperature range, the charging will continue
again after 0.5 seconds. The VA7205 can also
dynamically compensate the battery pack’s
internal impedance to reduce the charge time.
LED
S
T
S
VSS
1
2
3
BAT 4
VA7205CF
Top
View
(Not to
Scale)
8 VCC
7 CS2/LEDT
6 CS1
5
DRIV
E
Figure 1 VA7205CF 8-Pin SOP
Vimicro Copyright© 1999-2005
1






VA7205 Datasheet, Funktion
VA7205_100-1.3_En
www.DataSheet4U.com
Any
State
VCC<VBAT
Sleep Mode
Red LED Off
Green LED Off
Any
State
VBAT<VCC<VUVLO
VCC>VBAT
Abnormal Battery State
Wait for Restart
Red LED Blink
Green LED Off
Timer>15min
VTS1<VTS<VTS2,
exceeded 0.5 sec
Abnormal Battery
Temperature Range
Charge Paused
Red LED Blink
Green LED Off
VTS<VTS1 or
VTS>VTS2
exceeded
0.5 sec
Low Supply Voltage
Red LED Off
Green LED Off
VCC>VUVLO
Precharge
Started Timer
Red LED On (VBAT>VBSC)
Red LED Blink (V BAT<VBSC)
Green LED Off
VBAT>VMIN
Current Regulation
Charge
Red LED On
Green LED Off
VBAT<VMIN
ICHG=IREG
ICHG<IREG
Voltage Regulation
Charge
Red LED On
Green LED Off
VBAT<VMIN
Charge
Termination ICHRG<ITERM
Detect
Charge
Termination
Red LED Off
Green LED On
Recharge
Detect
VBAT<VRECHG
Figure 5 Operation State Diagram
6

6 Page









VA7205 pdf, datenblatt
Packaging
www.DataSheet4U.com
VA7205_100-1.3_En
Figure 6 VA7205 8-Pin SOP Mechanical Date
(unit: mm unless otherwise specified)
12

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