NCP367

http://onsemi.com

9

APPLICATION INFORMATION

Operation

The NCP367 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 +30 V, 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 4.3 V, 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 2.3 A. 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

USB/500 mA or WA/1.5 A is detected, without changing

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 any conditions, 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 1.85 V

plus hysteresis nominal. This circuit has a 80 mV

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 100 mV hysteresis to provide

FLAG Output

NCP367 provides a FLAG output, which alerts external

systems that a fault has occurred.

or internal temperature thresholds are exceeded and

remains low until between minimum driving voltage and

UVLO threshold. When Vin level recovers normal

condition, FLAG is held high. The pin is an open drain

output, thus a pull up resistor (typically 1 M

W − Minimum

10 k

output, which is able to support 1 mA maximum.

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.

Overcurrent Protection (OCP)

This device integrates the overcurrent protection

function, from wall adapter to battery. That means the

current across the internal PMOS is regulated and cut when

An internal resistor is placed in series with the pin

directly connected to GND.

the OCP value is decreased.

An additional logic pin, GS (gain select), is very useful

in case of different charge rate is necessary (Wall adapter

and USB, for example).

By setting GS to 0.4 V, overcurrent thresholds are

depending on R select resistor, which is connect between

pin 4 and GND. When the GS pin is tied to 1.2 V (high logic

level) the preselected current limit is divided by 2.75. Due