L6924D STMicroelectronics, L6924D Datasheet - Page 15

• Manufacturer Part Number: L6924D
• Description: IC BATTERY CHARGER SYS 16-VFQFPN
• Manufacturer: STMicroelectronics

Specifications of L6924D

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion), Lithium-Polymer (Li-Pol)
• Voltage - Supply: 2.5 V ~ 12 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-VFQFN
• Product: Charge Management
• Output Current: 30 mA
• Operating Supply Voltage: 2.5 V to 12 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• For Use With: 497-8428 - BOARD EVAL CHARGER ST7260/L6924D497-8247 - BOARD EVAL FOR L6924UTR497-5504 - EVAL BOARD FOR L6924D
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L6924D
Where,
I
The difference between the set charge current and the adapter limit should be high enough
to minimize the R
completely unbalanced and the power element is fully turned on.
Figure 8
adapter current limit of 500 mA.
Figure 8.
Neglecting the voltage drop across the charger (ΔV
condition, its input voltage is equal to the battery one, and so a very low operating input
voltage (down to 2.5 V) is required. The power dissipated by the device during this phase is:
Equation 4
When the battery voltage approaches the final value, the charger gets back the control of
the current, reducing it. Due to this, the upstream adapter exits the current limit condition
and its output goes up to the regulated voltage V
dissipation:
Equation 5
In conclusion, the advantage of the linear charging approach is that the designer has the
direct control of the charge current, and consequently the application can be very simple.
The drawback is the high power dissipation.
The advantage of the Quasi-Pulse charging method is that the power dissipated is
dramatically reduced. The drawback is that a dedicated upstream adapter is required.
LIM
= current limit of the wall adapter, and R
shows the R
R
DS(on)
DS(on)
curves vs charging current and output voltage
DS(on)
value (and the power dissipation). This makes the control loop
values for different output voltage and charging currents for an
Doc ID 11908 Rev 9
P
DIS
P
CH
=
(
=
V
ADP
R
DS
DS(on)
−
(
on
V
)
ADP
BAT
×
= resistance of the power MOSFET.
MOS
I
. This is the worst case in power
)
LIM
×
) when the device operates in this
I
2
LIM
Operation description
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