L6924U STMicroelectronics, L6924U Datasheet - Page 15

• Manufacturer Part Number: L6924U
• Description: Battery Management USB Battery Charger System w/integra
• Manufacturer: STMicroelectronics

Specifications of L6924U

• Product: Charge Management
• Battery Type: Li-Ion
• Output Voltage: 4.2 V
• Output Current: 30 mA
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Package / Case: VFQFPN
• Mounting Style: SMD/SMT
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6924U
Where ΔV
Equation 3
Where,
I
The difference between the programmed charge current and the adapter limit should be
high enough to minimize the R
control loop 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:
LIM
= current limit of the wall adapter, and R
shows the R
MOS
R
DS(on)
is given by:
curves vs. charging current and output voltage
DS(on)
values for different output voltages and charging currents for an
Doc ID 14716 Rev 2
DS(on)
Δ
value (and the power dissipation). This makes the
P
V
CH
MOS
=
R
=
DS
DS(on)
R
(
on
DS
)
ADP
(
×
ON
I
= resistance of the power MOSFET.
LIM
)
MOS
×
. This is the worst case in power
I
LIM
2
) when the device operates in this
Operation description
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