FP7176

This datasheet contains new product information.

Feeling Technology reserves the rights to modify the product specification without notice.

No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.

Rev. 0.64

7/14

Function Description

Input Voltage Regulator

The FP7176 can be powered directly from its VIN pin and can work from 8.5 - 450VDC at its VIN

pin. When a voltage is applied at the VIN pin, the FP7176 maintains a constant 7.5V at the VDD pin.

This voltage is used to power the IC and any external resistor dividers needed to control the IC. The

VDD pin must be bypassed by a low ESR capacitor to provide a low impedance path for the high

frequency current of the output GATE driver.

The FP7176 can also be operated by supplying a voltage at the VDD pin greater than the

internally regulated voltage. This will turn off the internal linear regulator of the IC and the FP7176 will

operate directly off the voltage supplied at the VDD pin. Please note that this external voltage at the

VDD pin should not exceed 8.5V.

Although the VIN pin of the FP7176 is rated up to 450V, the actual maximum voltage that can be

applied is limited by the power dissipation in the IC. For example, if an 8-pin SOIC (junction to ambient

thermal resistance Rθ,j-a = 128°C/ W) FP7176 draws about I

maximum allowable temperature rise of the junction temperature limited to about ΔT = 100°C, the

maximum voltage at the VIN pin would be:

V

390

=

mA

2

1

×

W

/

C

128

C

100

=

I

1

×

R

T

Δ

=

V

o

o

in

a

j

,

θ

)

MAX

(

IN

In these cases, to operate the FP7176 from higher input voltages, a Zener diode can be added in

series with the VIN pin to divert some of the power loss from the FP7176 to the Zener diode. In the

above example, using a 100V Zener diode will allow the circuit to easily work up to 490V.The input

current drawn from the VIN pin is represented by the following equation:

S

G

IN

f

×

Q

+

mA

5

.

0

I

≈

FET (which can be obtained from the datasheet of the FET).