L6924U STMicroelectronics, L6924U Datasheet - Page 23

• 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
8
Figure 16. Power dissipation in both linear and quasi pulse modes with thermal loop
8.1
Application information: monitoring and protection
The L6924U uses a VFQFPN (3 x 3 mm) 16-pin package with an exposed pad that allows
the user to have a compact application and good thermal behavior at the same time. The
L6924U has a low thermal resistance because of the exposed pad (approximately
75 °C/W, depending on the board characteristics). Moreover, a built-in thermal protection
feature prevents the L6924U from having thermal issues typically present in a linear charger.
Thermal control is implemented with a thermal loop that reduces the charge current
automatically when the junction temperature reaches approximately 120 °C. This avoids
further temperature rise and keeps the junction temperature constant. This simplifies the
thermal design of the application as well as protects the device against over-temperature
damage.
Figure 16
reaches 120 °C.
NTC thermistor
The device allows designers to monitor the battery temperature by measuring the voltage
across an NTC or PTC resistor. Li-Ion batteries have a narrow range of operating
temperature, usually from 0 °C to 50 °C. This window is programmable by an external
divider which is comprised of an NTC thermistor connected to GND and a resistor
connected to V
voltage threshold (internal window comparator), the device stops the charge process, and
indicates a fault condition through the status pin.
shows how the thermal loop acts (dotted lines), when the junction temperature
REF
. When the voltage on the TH pin exceeds the minimum or maximum
Doc ID 14716 Rev 2
Application information: monitoring and protection
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