MCP73223T-C2SISLASHMF datasheet(19/34 Pages) MICROCHIP

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DS22191A-page 19

MCP73123/223

5.9

Thermal Regulation

The MCP73123/223 shall limit the charge current

based on the die temperature. The thermal regulation

optimizes the charge cycle time while maintaining

device reliability.

Figure 5-1 depicts the thermal

regulation for the MCP73123/223 device. Refer to

Section 1.0 “Electrical Characteristics” for thermal

package resistances and

Section 6.1.1.2 “Thermal

Considerations” for calculating power dissipation.

FIGURE 5-1:

Thermal Regulation

5.10

Thermal Shutdown

The MCP73123/223 suspends charge if the die

temperature exceeds +150°C. Charging will resume

when the die temperature has cooled by approximately

10°C. The thermal shutdown is a secondary safety

feature in the event that there is a failure within the

thermal regulation circuitry.

5.11

Status Indicator

The charge status outputs are open-drain outputs with

two different states: Low (L), and High Impedance

(Hi-Z). The charge status outputs can be used to

illuminate LEDs. Optionally, the charge status outputs

can be used as an interface to a host microcontroller.

Table 5-2 summarize the state of the status outputs

during a charge cycle.

5.12

BATTERY SHORT PROTECTION

Once a lithium iron phosphate battery is detected, an

internal battery short protection (BSP) circuit starts

monitoring the battery voltage. When VBAT falls below

a typical 1.7V battery short protection threshold voltage

per

cell,

the

charging

behavior

postponed.

25 mA (typical) detection current is supplied for

recovering from battery short condition.

Preconditioning mode resumes when VBAT raises

above battery short protection threshold. The battery

voltage must rise approximately 150 mV above the

battery short protection voltage before the MCP73123/

223 device become operational.

100

200

300

400

500

600

25 35 45 55 65 75 85 95 105 115 125 135 145

Junction Temperature (°C)

VDD = 5.2V

RPROG = 2 kΩ

TABLE 5-2:

STATUS OUTPUTS

CHARGE CYCLE

STATE

STAT

Shutdown

Hi-Z

Standby

Hi-Z

Preconditioning

Constant Current Fast

Charge

Constant Voltage

Charge Complete - Standby

Hi-Z

Temperature Fault

1.6 second 50% D.C.

Flashing (Type 2)

Hi-Z (Type 1)

Timer Fault

1.6 second 50% D.C.

Flashing (Type 2)

Hi-Z (Type 1)

Preconditioning Timer Fault

1.6 second 50% D.C.

Flashing (Type 2)

Hi-Z (Type 1)

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