Datasheet LTC4124 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | 100mA Wireless Li-Ion Charger with Low Battery Disconnect |
| Pages / Page | 28 / 9 — OPERATION. WIRELESS POWER MANAGER. Figure 1. Wireless Power Transfer … |
| File Format / Size | PDF / 1.9 Mb |
| Document Language | English |
OPERATION. WIRELESS POWER MANAGER. Figure 1. Wireless Power Transfer System. Figure 2. Typical Charging Cycle at 0.5C Rate vs
Text Version of Document
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OPERATION
The LTC4124 is a wireless single cell Li-Ion battery char- detection, temperature qualified safe charging and auto- ger. The part has three main components: a wireless matic recharge. The charge voltage and charge current are power manager, a full-featured linear battery charger and pin-strap programmable according to Table 2 and Table 3 an ideal diode PowerPath™ controller. shown in the Pin Functions section. Figure 2 and Figure 3 show a typical charging cycle. As
WIRELESS POWER MANAGER
soon as the voltage at the VCC pin reaches 3.4V, the char- A complete wireless power transfer system consists of ger attempts to charge the battery and a charge cycle transmit circuitry with a transmit coil and receive circuitry is initiated. At the beginning of a charge cycle, when with a receive coil (Figure 1). The LTC4124 connected to the battery voltage is typically less than the recharge an LC tank creates a simple and complete receiver half of threshold (97.6% of the final charge voltage), the char- the wireless power transfer system. ger is in CC mode and charges the battery at the full programmed current. LTX LRX COIL COIL 120 120 (% OF PROGRAMMED CHARGE VOL LTC4124 TRANSMITTER RECEIVER 100 100 + CIRCUIT CIRCUIT – VIN RL BA 80 80 T 4124 F01 TER AIR GAP Y VOL LOW COUPLING BETWEEN COILS 60 60 TAGE
Figure 1. Wireless Power Transfer System
CHARGE CURRENT 40 40 T Refer to the Functional Block Diagram for the following 20 20 AGE) CHARGE CURRENT discussion. An external parallel resonant LC tank con- (% OF PROGRAMMED CHARGE CURRENT) BATTERY VOLTAGE 0 0 nected to the ACIN pin allows the LTC4124 to receive 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 TIME (HOURS) power wirelessly from an alternating magnetic field gener- 4124 F02 ated by a transmit coil. Diode D1 rectifies the AC voltage
Figure 2. Typical Charging Cycle at 0.5C Rate vs
at the ACIN pin. Comparator CP1, switch SW1 and switch
Time with Pre-Charge Disabled
SW2 operate together to regulate the rectified voltage on the VCC pin to between 0.85V and 1.05V above the voltage 100 on the BAT pin provided BAT ≥ 2.8V. 90 80
Operation with an Optional DC Voltage Source
70 The LTC4124 can alternately be powered from a DC volt- 60 age source connected to the DCIN pin. Diodes D1 and D2 50 set V 40 CC to the maximum of the voltage on the DCIN pin or the peak AC voltage on the ACIN pin. Therefore, the CHARGE CURRENT 30 DCIN pin supplies power to the V 20 CC pin only if its voltage is higher than instantaneous AC voltage on the ACIN pin. 10 (% OF PROGRAMMED CHARGE CURRENT) 050 60 70 80 90 100 110 BATTERY VOLTAGE (% OF FINAL CHARGE VOLTAGE)
BATTERY CHARGER
4124 F03 The LTC4124 includes a pin programmable full-featured
Figure 3. Typical Charge Current vs Battery Voltage
CC/CV (Constant Current/Constant Voltage) linear bat-
in a Charging Cycle with Pre-Charge Disabled
tery charger with safety timer termination, bad battery Rev. 0 For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
OPERATION
The LTC4124 is a wireless single cell Li-Ion battery char- detection, temperature qualified safe charging and auto- ger. The part has three main components: a wireless matic recharge. The charge voltage and charge current are power manager, a full-featured linear battery charger and pin-strap programmable according to Table 2 and Table 3 an ideal diode PowerPath™ controller. shown in the Pin Functions section. Figure 2 and Figure 3 show a typical charging cycle. As
WIRELESS POWER MANAGER
soon as the voltage at the VCC pin reaches 3.4V, the char- A complete wireless power transfer system consists of ger attempts to charge the battery and a charge cycle transmit circuitry with a transmit coil and receive circuitry is initiated. At the beginning of a charge cycle, when with a receive coil (Figure 1). The LTC4124 connected to the battery voltage is typically less than the recharge an LC tank creates a simple and complete receiver half of threshold (97.6% of the final charge voltage), the char- the wireless power transfer system. ger is in CC mode and charges the battery at the full programmed current. LTX LRX COIL COIL 120 120 (% OF PROGRAMMED CHARGE VOL LTC4124 TRANSMITTER RECEIVER 100 100 + CIRCUIT CIRCUIT – VIN RL BA 80 80 T 4124 F01 TER AIR GAP Y VOL LOW COUPLING BETWEEN COILS 60 60 TAGE
Figure 1. Wireless Power Transfer System
CHARGE CURRENT 40 40 T Refer to the Functional Block Diagram for the following 20 20 AGE) CHARGE CURRENT discussion. An external parallel resonant LC tank con- (% OF PROGRAMMED CHARGE CURRENT) BATTERY VOLTAGE 0 0 nected to the ACIN pin allows the LTC4124 to receive 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 TIME (HOURS) power wirelessly from an alternating magnetic field gener- 4124 F02 ated by a transmit coil. Diode D1 rectifies the AC voltage
Figure 2. Typical Charging Cycle at 0.5C Rate vs
at the ACIN pin. Comparator CP1, switch SW1 and switch
Time with Pre-Charge Disabled
SW2 operate together to regulate the rectified voltage on the VCC pin to between 0.85V and 1.05V above the voltage 100 on the BAT pin provided BAT ≥ 2.8V. 90 80
Operation with an Optional DC Voltage Source
70 The LTC4124 can alternately be powered from a DC volt- 60 age source connected to the DCIN pin. Diodes D1 and D2 50 set V 40 CC to the maximum of the voltage on the DCIN pin or the peak AC voltage on the ACIN pin. Therefore, the CHARGE CURRENT 30 DCIN pin supplies power to the V 20 CC pin only if its voltage is higher than instantaneous AC voltage on the ACIN pin. 10 (% OF PROGRAMMED CHARGE CURRENT) 050 60 70 80 90 100 110 BATTERY VOLTAGE (% OF FINAL CHARGE VOLTAGE)
BATTERY CHARGER
4124 F03 The LTC4124 includes a pin programmable full-featured
Figure 3. Typical Charge Current vs Battery Voltage
CC/CV (Constant Current/Constant Voltage) linear bat-
in a Charging Cycle with Pre-Charge Disabled
tery charger with safety timer termination, bad battery Rev. 0 For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
