TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R28
Design-in
Page 77 of 164
Constant voltage: when the battery voltage reaches the regulated output voltage (4.2 V), the
L6924U starts to reduce the current until the charge termination is done. The charging process
ends when the charging current reaches the value configured by an external resistor to ~15 mA or
when the charging timer reaches the value configured by an external capacitor to ~9800 s
Using a battery pack with an internal NTC resistor, the L6924U can monitor the battery temperature
to protect the battery from operating under unsafe thermal conditions.
Alternatively the L6924U, providing input voltage range up to 12 V, can charge from an AC wall
adapter. When a current-limited adapter is used, it can operate in quasi-pulse mode, reducing power
dissipation.
C5
C8
C7
C6
C9
GND
TOBY-L2 series
71
VCC
72
VCC
70
VCC
+
USB
Supply
C3 R4
θ
U1
I
USB
I
AC
I
END
T
PRG
SD
V
IN
V
INSNS
MODE
ISEL
C2
C1
5V0
TH
GND
V
OUT
V
OSNS
V
REF
R1
R2
R3
Li-Ion/Li-Pol
Battery Pack
D1
B1
C4
Li-Ion/Li-Polymer
Battery Charger IC
C10
Figure 38: Li-Ion (or Li-Polymer) battery charging application circuit
Reference
Description
Part Number – Manufacturer
B1
Li-Ion (or Li-Polymer) battery pack with 470
NTC
Various manufacturer
C1, C4
1
µ
F Capacitor Ceramic X7R 0603 10% 16 V
GRM188R71C105KA12 – Murata
C2, C6
10 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C103KA01 – Murata
C3
1 nF Capacitor Ceramic X7R 0402 10% 50 V
GRM155R71H102KA01 – Murata
C5
330
µ
F Capacitor Tantalum D_SIZE 6.3 V 45 m
T520D337M006ATE045 – KEMET
C7
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R61A104KA01 – Murata
C8
68 pF Capacitor Ceramic C0G 0402 5% 50 V
GRM1555C1H680JA01 – Murata
C9
15 pF Capacitor Ceramic C0G 0402 5% 50 V
GRM1555C1H150JA01 – Murata
C10
8.2 pF Capacitor Ceramic C0G 0402 5% 50 V
GRM1555C1H8R2DZ01 – Murata
D1
Low Capacitance ESD Protection
USB0002RP or USB0002DP – AVX
R1, R2
24 k
Resistor 0402 5% 0.1 W
RC0402JR-0724KL – Yageo Phycomp
R3
3.3 k
Resistor 0402 5% 0.1 W
RC0402JR-073K3L – Yageo Phycomp
R4
1.0 k
Resistor 0402 5% 0.1 W
RC0402JR-071K0L – Yageo Phycomp
U1
Single Cell Li-Ion (or Li-Polymer) Battery Charger IC
L6924U – STMicroelectronics
Table 20: Suggested components for Li-Ion (or Li-Polymer) battery charging application circuit
2.2.1.8
Guidelines for battery charging and power path management circuit
Application devices where both a permanent primary supply / charging source (e.g. ~12 V) and a
rechargeable back-up battery (e.g. 3.7 V Li-Pol) are available at the same time as possible supply
source should implement a suitable charger / regulator with integrated power path management
function to supply the module and the whole device while simultaneously and independently charging
the battery.
reports a simplified block diagram circuit showing the working principle of a
charger / regulator with integrated power path management function. This component allows the
