EM1109BV datasheet(9/16 Pages) EXCELLIANCE

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EM1109BV

2020/12/30

A.1

Functional Description

Enable Function

EM1109BV is enabled if the voltage of the EN pin is

greater than 1.2V. If the voltage of the EN pin is

less than 0.3V, the IC will be disabled.

POR – Power ON Reset

To let EM1109BV start to operation, input voltage

must be higher than its POR voltage even when EN

voltage is pulled higher than enable high voltage.

Typical POR voltage is 2.1V.

Over Current Limit Function

EM1109BV-AJ

features over

current

limiting

function which can limit its output current to 1.3A.

Input and Output Capacitor Selection

For VIN pin, 1uF or larger ceramic capacitor is

required to provide bypass path in transient

current demand. VOUT pin is also recommended to

have 4.7uF or larger ceramic capacitor to be stable

and reduce the VOUT voltage dip when fast loading

transient is happened.

Thermal and Layout Consideration

EM1109BV is designed to maintain a constant

output load current. Due to physical limitations of

the chip layout and assembly of the device the

maximum switch current is 1A. All copper traces

for the VIN and Vo pin should be widely and short

to carry the maximum continuous current and

obtain the best effect. The maximum IC junction

temperature should be restricted to 125℃ under

normal operating conditions. To calculate the

maximum allowable dissipation, PD(MAX) for a given

output current and ambient temperature, used the

following equation:

MAX







)

(

)

(

Where:

PD(MAX)=Maximum allowable power dissipation

TJ(MAX)=Maximum allowable junction temperature

(125 ℃ for the EM1109BV)

TA=Ambient Temperature of the device

Power Good Function

The power good circuit monitors the feedback

voltage at output. When the ADJ voltage falls below

the PG threshold, the control circuit pull this to pin

to GND. When the ADJ voltage rising above the PG

threshold, this pin becomes high impedance. By

connecting a pullup resistor to an external supply,

any downstream device can receive power good

signal that can be used for managing any fault

event and sequencing. Using the pullup resistor

from 10KΩ to 100KΩ is recommended. The state

of PG is only valid when the device is operating

above the minimum input voltage. When the input

voltage falls below 1V, there is not enough driver to

keep the open drain and power good device turned

on so that the PG output is pulled up. Connecting

the PG pull up to the output can help minimize the

effect.

EM1109BV Datasheet(PDF) 9 Page - Excelliance MOS Corp.

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