NCP1395 データシートの表示（PDF） - ON Semiconductor

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NCP1395

High Performance Resonant Mode Controller

ON Semiconductor 

NCP1395A/B

• Finally, Two Circuit Versions, A and B: The A and

B versions differ because of the following changes:

1. The startup thresholds are different, the A starts

to pulse for VCC = 12.8 V whereas the B pulses

for VCC = 10 V. The turn off levels are the

same, however. The A is recommended for

consumer products where the designer can use

an external startup resistor, whereas the B is

Voltage−Controlled Oscillator

The VCO section features a high−speed circuitry

allowing an internal operation from 100 kHz up to

2.0 MHz. However, as a division by two internally creates

the two Q and Qbar outputs, the final effective signal on

more recommended for industrial/medical

applications where a 12 V auxiliary supply

directly powers the chip.

2. The A version does not activate the soft−start

upon release of the fast fault input. This is to let

the designer implement skip cycle. To the

opposite, the B version goes back to operation

upon the fast fault pin release via a soft−start

sequence.

output A and B switches between 50 kHz and 1.0 MHz.

The VCO is configured in such a way that if the feedback

pin goes up, the switching frequency also goes up.

Figure 33 shows the architecture of this oscillator.

Vref

Fmin

Rt−m sets

Fmin for V(FB) < Vfb_off

Vdd

Imin

FBinternal

+

−

0 to I_Fmax

max

Fsw

max

+

−

Cint

+

S

DQ

Clk Q

R

Vdd

IDT

Vref

DT

Rdt sets

the deadtime

Fmax

Vcc Rt−max sets

the maximum Fsw

Imin

Vdd

FB

Rfb

20 k

A

B

−

+

+

Vb_fault

Vfb < Vb_fault

start fault timer

Figure 33. Simplified VCO Architecture

http://onsemi.com

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