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Datasheet

Datasheet

BM1Q011FJ

TSZ02201-0F1F0A200180-1-2

21.Jan.2016 Rev.001

© 2016 ROHM Co., Ltd. All rights reserved.

www.rohm.com

TSZ22111・15・001

・

Regarding capacitor value of VCC pin

For stable operation of the IC, please set the capacitor value to 1uF or higher of the VCC pin. When the VCC

capacitor terminal is too large, the response of the VCC pin to the Secondary output is slows down. Additionally,

if the degree of the transformer coupling is low, since a large surge occurs to the VCC pin, the IC may be

destroyed. In this case, it is necessary that a resistor which is from 10Ω to 100Ω is attached to the path between

the capacitor and diode at the back of the auxiliary winding or the capacitor of the VCC pin is increased. And the

fixed number is has to be set the VCC pin surge voltage not to exceed the absolute maximum rating of the VCC

pin by evaluating the waveform of the VCC pin.

・

Regarding VCC OVP voltage protection setting method in case of rising Vout (secondary output)

The VCC pin voltage is determined by the transformer ratio (Np:Ns) and Vout (Secondary output). Therefore,

when the Secondary output becomes large, it is possible to protect the IC by VCCOVP. Setting method of

VCCOVP protection is shown below.

Figure 12. How to Set VCCOVP

The VCC voltage is determined by the formula below.

VCC voltage = (Vout-VFs)×Nb/Ns -VFb

(Vout: Secondary output, Nb: Number of auxiliary winding, Ns: Number of secondary winding

VFx: Secondary diode VF, VFb: auxiliary winding diode VF)

If you want to apply protection when it becomes Secondary output × 1.3, please set the number of turns to be the next

formula. 1.3 × (Vout × (Nb/Ns) - VF) > VOVP1

Np

Nb

Ns

Vout