STMICROELECTRONICS EVAL6924D

EVAL6924D
EVAL6924D Battery charger system
with integrated Power Switch for Li-ION/Li-POLYMER
Data Brief
General description
many parameters, such as pre-charge current,
fast-charge current, pre-charge voltage threshold,
end-of-charge current threshold, and charge
timer.
The L6924D is a fully monolithic battery charger
dedicated to single-cell Li-Ion/Polymer battery
packs. It is the ideal solution for space-limited
applications, like PDAs, handheld equipment,
cellular phones, and digital cameras. It is
designed with BCD6 technology and integrates all
of the power elements (the Power MOSFET,
reverse blocking diode and the sense resistor) in
a small VFQFPN16 3mm x 3mm package.
The L6924D offers two open collector outputs for
diagnostic purposes, which can be used to either
drive two external LEDs or communicate with a
host microcontroller. Finally, the L6924D also
provides very flexible control of the charge
process termination and Gas Gauge capability, as
well as other functions, such as checking for
battery presence, and monitoring and protecting
the battery from unsafe thermal conditions.
When an external voltage regulated wall adapter
is used, the L6924D works in Linear Mode, and
charges the battery in a Constant
Current/Constant Voltage (CC/CV) profile.
Moreover, when a current-limited adapter is used,
the device can operate in Quasi-Pulse Mode,
dramatically reducing the power dissipation.
Regardless of the charging approach, a closed
loop thermal control avoids device overheating.
The EVAL6924D Evaluation Board integrates the
linear battery charger as well as the external
components required for a typical application.
The input voltage range can be adjusted between
2.5V and 12V, while the output voltage is selected
by J4, between 4.1V and 4.2V, depending on the
battery type. The fast charge current is set to 500
mA through the 24K R5 resistor.
The device has an operating input voltage ranging
from 2.5V to 12V and it allows the user to program
Evaluation board
November 2006
Rev 1
For further information contact your local STMicroelectronics sales office.
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Features
1
EVAL6924D
Features
Figure 1.
Evaluation board schematic
R9
R3
C4
CHARGER
V IN
NTC
V REF
TH
V OUT
V INSNS
R1
BATTERY
V OSNS
C1
IEND
R2
T PRG
C2
LD1
IPRG
L6924D
C3
LD2
J2
R4
ST2
V PRE
ST1
R5
J5
J1
SHDN
GND
V OPRG
IPRE
R6
J3
R10
J4
∝C
Vref
R7
Table 1.
Name
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R8
Evaluation board part list
Value
Description
R1
1K
Pull up resistor. To be used when the ST1s connected with a LED
R2
1K
Pull up resistor. To be used when the ST1s connected with a LED
R3
1K
Pull up resistor. Connected between VREF and TH pin
R4
3K3
End of charge current resistor. Used to set the termination current and, as a
“Gas Gauge“ when measuring the voltage across on it.
R5
24K
Fast-charge current resistor. Used to set the charging current
R6
N.M
VPRETH resistor. Used to set programmable pre-charge voltage threshold. If
not mounted, the VPRETHDefault, equal to 2.8V, is set
R7
N.M
IPRETH resistor. Used to set programmable pre-charge voltage threshold below
the default one. If not mounted, the IPRETHDefault, is set
R8
68K
IPRETH resistor. Used to set programmable pre-charge current threshold above
the default one. If not mounted, the IPRETHDefault, is set
R9
470R
If a NTC is not used, a half value of R3 must be mounted to keep the TH
voltage in the correct window
R10
N.M
It has the same function of R6. Moreover, if it is replaced with a short-circuit,
when J5 is closed, the timer is reset (falling edge)
C1
1µF
Input capacitor
C2
10nF
TMAX capacitor. Used to set the maximum charging time
C3
1µF
Output capacitor
C4
1µF
VREF filter capacitor. Not mounted
LD1
GREEN
ST1 LED
EVAL6924D
Revision history
Figure 2.
2
Package - VFQFPN16
Revision history
Table 2.
Revision history
Date
Revision
21-Nov-2006
1
Changes
First issue
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EVAL6924D
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