L6924D STMicroelectronics, L6924D Datasheet - Page 11

• 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
6
Operation description
The L6924D is a fully integrated battery charger that allows a very compact battery
management system for space limited applications. It integrates in a small package, all the
power elements: power MOSFET, reverse blocking diode and the sense resistor.
It normally works as a linear charger when powered from an external voltage regulated
adapter. However, thanks to its very low minimum input voltage (down to 2.5 V) the L6924D
can also work as a Quasi-Pulse charger when powered from a current limited adapter. To
work in this condition, is enough to set the device’s charging current higher than the
adapter’s one
that the device has a direct control of the charging current and so the designer needn’t to
rely on the upstream adapter. However, the advantage of the Quasi-Pulse approach is that
the power dissipated inside the portable equipment is dramatically reduced.
The L6924D charges the battery in three phases:
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●
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The full flexibility is provided by:
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If the full flexibility is not required and a smaller number of external components is preferred,
default values of I
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●
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The voltage across the resistor connected between I
the actual charging current (working as a Gas Gauge), and it can be easily fed into a µC
ADC.
Pre-Charge constant current: in this phase (active when the battery is deeply
discharged) the battery is charged with a low current.
Fast-Charge constant current: in this phase the device charges the battery with the
maximum current.
Constant Voltage: when the battery voltage reaches the selected output voltage, the
device starts to reduce the current, until the charge termination is done.
Programmable pre-charging current and voltage thresholds (I
(Chapter 7.2 on page
Programmable fast-charging current (I
Programmable end of charge current threshold (I
Programmable end of charge timer (T
If a PTC or NTC resistor is used, the device can monitor the battery temperature in
order to protect the battery from operating in unsafe thermal conditions.
Beside the good thermal behavior guaranteed by low thermal resistance of the
package, additional safety is provided by the built-in temperature control loop. The IC
monitors continuously its junction temperature. When the temperature reaches
approximately 120°C, the thermal control loop starts working, and reduces the charging
current, in order to keep the IC junction temperature at 120°C.
Two open collector outputs are available for diagnostic purpose (status pins ST1 and
ST2). They can be also used to drive external LEDs or to interface with a
microcontroller.
(Chapter 7.4 on page
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and V
17,
PRETH
Doc ID 11908 Rev 9
Chapter 7.3 on page
18). The advantage of the linear charging approach is
are available leaving the respective pins floating.
MAXCH
CHG
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(Chapter 7.4 on page
)
(Chapter 7.8 on page
17).
END
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and GND gives information about
)
(Chapter 7.5 on page
PRETH
Operation description
18).
20).
and V
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19).
)
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