AL1676

Document number: DS38290 Rev. 1 - 2

10 of 15

www.diodes.com

February 2016

© Diodes Incorporated

AL1676

Over-Temperature Protection (OTP)

The AL1676 has OTP protection function. When the junction temperature reaches +170°C typical, the IC will trigger an over-temperature

protection condition which causes the device to shut down and latch. Once OTP has triggered, the system will resume after the system

’s input

power supply has been reset and power up.

Design Parameters

Setting the Current Sense Resistor R5

In buck structure, when output is larger than input, no energy will be transferred to output, this period is called dead zone, and the dead zone

angle is

θ .

_

= sin

2

O

IN

RMS

V

a

V





Where,

The AL1676 adopts boundary conduction mode, the output current is calculated as below,

-

_

_

11

(sin( )

)

2

2

o

ON

OFF

O MEAN

PEAK

ON

OFF

DELAY

IN

RMS

V

t

t

I

I

dt

t

t

t

V











 











Where,

The AL1676 is a closed loop constant current control, so it has the equation.

-

_

1

(sin( )

) R5

2

o

ON

OFF

REF

PEAK

ON

OFF

DELAY

IN

RMS

V

t

t

V

I

dt

t

t

t

V











 











Where,

So we can get the output current equation as below,

_

1

=

25

REF

O MEAN

V

I

R



Inductance Selection (L1)

In buck structure, the peak current of the inductor can be calculated as below,

-

_

5

(sin( )

)

2

REF

PEAK

o

ON

OFF

ON

OFF

DELAY

IN

RMS

V

I

V

t

t

R

dt

t

t

t

V























