DIO58020

Version 1.4, Mar 2025

www.dioo.com

© 2025 Dioo Microcircuits Co., Ltd. Jiangsu

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The device enters constant-temperature (CT) mode when the die temperature attempts to rise above the

preset value of approximately 130°C. At this point, an internal thermal feedback loop reduces the

programmed charge current. This feature protects the DIO58020 series from excessive temperature,

allowing the user to push the limits of the power handling capability of a given circuit board without the risk

of damaging the DIO58020 series

.

8.1.3. Automatic recharge mode

The device also has automatic recharge mode. Once the charge cycle is terminated, the series of

DIO58020 continuously monitors the voltage on the BAT pin using a comparator with a 6 ms filter time

(tRECHRG). A charge cycle restarts when the battery voltage falls below 4.25 V / 4.215 V / 4.2 V / 4.05 V (Typ.),

which corresponds to approximately 80% to 90% battery capacity. This ensures that the battery is kept at or

near a fully charged condition and eliminates the need for periodic charge cycle initiations. CHGb output

enters a pull-down state during recharge cycles.

8.1.4. Communication mode

The DIO58020 series enters communication mode when EN is pulled high and the VIN range is 0 to 2.8 V. During

communication mode, the electrical information are communicated between IN and COM pins, and the

communication rate can up to 1 Mbps. The value of ICOM drops to 25

μA.

8.2. Operation mode transition

The transition among operation modes is determined according to these variables respectively:



Logic level at EN pin



Logic level at VIN pin

Status logic level at State pin: State = 0 indicates ready to charge; State = 1 indicates unable to charge.

The comprehensive charging procedure, exemplified by DIO58020A with a final float voltage of 4.4 V, is

detailed as follows. Initially, the EN pin is left floating to initiate the sleep mode. Activation from this sleep

state necessitates forced charging, which requires VIN to exceed 4.5 V and remain so for a minimum of 5

seconds. Upon lowering VIN to the range of 0 to 2.8 V, the earphone and earbud enter a communication

mode, powered by the battery, where they exchange electrical information. In the event of an error or failure

in establishing communication, the earphone will wait for a duration of 20 ms before reverting to the sleep

mode to conserve energy. Upon successful completion of the communication phase, the earbud acquires

comprehensive battery data and subsequently supplies a precisely regulated VIN, as BAT + 100 mV, while

maintaining EN = 1 simultaneously. Throughout the charging process, the earbud continuously monitors the

charging current. If it falls below 60 mA (1C default), VIN is incremented by an additional 100 mV to

maintain constant current charging until VBAT reaches 4.4 V, indicating the battery is fully charged. The

charging mode concludes when the voltage across IBF drops below 0.5 V. The state diagram including the

possible transitions is shown in Figure 9.