NCP1607BDR2G. datasheet(21/23 Pages) ONSEMI

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NCP1607

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BOOST DESIGN EQUATIONS Components are identified in Figure 1

RMS Input Current

Iac

OUT

h @ Vac

h (the efficiency of only the Boost

PFC stage) is generally in the range

of 90 − 95%

Maximum Inductor Peak

Current

pk(MAX) +

@ 2 @ P

OUT

h @ Vac

Where VacLL is the minimum line in-

put voltage. Ipk(MAX) occurs at the

lowest line voltage.

Inductor Value

@ Vac2 @

OUT

* Vac

OUT @ Vac @ Ipk(MAX) @ fSW(min)

fSW(MIN) is the minimum desired

switching frequency. The maximum L

must be calculated at low line and

high line.

Maximum On Time

on(MAX) +

@ L @ P

OUT

h @ Vac

The maximum on time occurs at the

lowest line voltage and maximum

output power.

Off Time

off +

ton

OUT

Vac

@sin(q)@ 2

* 1

The off time is greatest at the peak of

the ac line voltage and approaches

zero at the ac line zero crossings.

Theta (

q) represents the angle of the

ac line voltage.

Frequency

SW +

Vac 2

@ h

@ L @ P

OUT

@ 1 *

Vac

@ |sin q| @ 2

OUT

Pin 3 Capacitor

@ P

OUT @ L @ ICHARGE

h @ Vac 2 @ V

CTMAX

ICHARGE and VCTMAX are given in

the NCP1607 specification table.

Boost Turns to ZCD Turns

Ratio

B :NZCD v

OUT * VacHL @

ZCDH

Where VacHL is the maximum line

input voltage. The turns ratio must be

low enough so as to trigger the ZCD

comparators at high line.

Resistor from ZCD wind-

ing to the ZCD pin (pin 5)

ZCD w

Vac

HL @

CL(NEG) @ (NB :NZCD)

RZCD must be large enough so that

the shutdown comparator is not inad-

vertently activated.

Boost Output Voltage

OUT + VREF @

OUT1 ) REQ

EQ +

OUT2 @ RFB

OUT2 ) RFB

Maximum VOUT voltage

prior to OVP activation and

the necessary ROUT1 and

ROUT2.

OUT(OVP) + VOUT ) IOVP @ ROUT1

OUT1 +

OUT(OVP) * VOUT

OVP

EQ + ROUT1 @

REF

OUT * VREF

OUT2 +

EQ ) RFB

FB * REQ

IOVP is given in the NCP1607 spe-

cification table.

Minimum output voltage

necessary to exit under-

voltage protection (UVP)

OUT(UVP) + VUVP @

OUT1 ) REQ

VUVP is given in the NCP1607 spe-

cification table.

Bulk Cap Ripple

ripple(pk−pk) +

OUT

BULK @ 2 @ p @ fline @ VOUT

Use fline = 47 Hz for worst case at

universal lines. The ripple must not

exceed the OVP level for VOUT.

Inductor RMS Current

L(RMS) +

@ P

OUT

@ Vac

LL @ h

Boost Diode RMS Current

D(RMS)MAX +

@ 2

p @

OUT

h @ Vac

LL @ VOUT

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