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Functional Description

Operation

The HM9519 is an integrated IC which offers a complete protection of the portable devices during the Li ion

battery charge.

First, the input pin is protected up to +30V, protecting the down stream system (charger, transceiver, system...)

against the power supply transients such as inrush current or defective functionality. Additional protection level is

offered with the overcurrent block which eliminates current peak or opens the charge path if an overcurrent

default appears.

More of that, the battery voltage is monitored all along the input power supply is connected, allowing to open

charge path if Li ion battery voltage exceeds 4.3V, caused by CCCV charger or battery pack fault.

The integrated pass element (PMOS FET) is sized to support very high charge DC current up to 2.3A. The

overcurrent threshold can be externally adjusted with a pull-down resistor and gain select pin is available to divide

current limit threshold with internal fixed gain. Allowing to adjust with logic pin the overcurrent threshold if

Undervoltage, Overvoltage, Overcurrent and thermal faults are signalized thanks to the open drain FLAG pin,

by pulling its down.

Undervoltage Lockout (UVLO)

To ensure proper operation under anyconditions, the device has a built−in undervoltage lock out (UVLO)

circuit. During Vin positive going slope, the output remains disconnected from input until Vin voltage is above

1.85V plus hysteresis nominal. This circuit has a 80mV hysteresis to provide noise immunity to transient

condition.

Overvoltage Lockout (OVLO)

To protect connected systems on Vout pin from overvoltage, the device has a built-in overvoltage lock out

(OVLO) circuit. During overvoltage condition, the output remains disabled as long as the input voltage exceeds

this threshold.

FLAG output is tied to low as long as Vin is higher than OVLO. This circuit has a 100mV hysteresis to

provide noise immunity to transient conditions.

FLAGOutput

HM9519

provides a FLAG output, which alerts external systems that a fault has occurred.

remains low until between minimum driving voltage and UVLO threshold. WhenVin level recovers normal

condition, FLAG is held high. The pin is an open drain output, thus a pull up resistor (typically1MΩ− Minimum

10 kΩ) must be provided to Vcc. FLAG pin is an open drain output, which is able to support 1mAmaximum.

EN Input

To enable normal operation, the EN pin shall be forced to low or connected to ground. A high level on the

pin,disconnects OUT pin from IN pin. EN does not overdrive a UVLO or OVLO fault.

HM