10/27

BM2P121XH-Z

TSZ02201-0F1F0A200560-1-2

17.Jan.2019 Rev.001

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TSZ22111

• 15 • 001

6.1

– continued

This IC enables simpler constitution with a few external parts by fixing the VCC pin voltage. When adjust the

output voltage, adding zener diodes makes it variable. However, it is necessary to consider the dispersion of the

zener diodes.

The variable output voltage is defined by the formula below. The voltage when the MOSFET is off is shown in

Figure 10.

Where:

Figure 10. Back Converter Output Dispersion Circuit (MOSFET = OFF)

6.2

Frequency Circuit

mode 1: Burst Mode

(The intermittent operation starts.)

mode 2: Frequency Modulation Mode

(It reduces the frequency.)

mode 3: Fixed Frequency Mode

(It operates in the maximum frequency.)

mode 4: Overload Mode

(The intermittent operation starts.)

Figure 11. State Transition of Switching Frequency

6.3

Frequency Hopping Function

Frequency hopping function achieves low EMI by change the frequency at random. The upper limit of the

frequency

’s wave width is ±6 % (Typ) for basic frequency.

ZD1

0 V

GND

VOUT

AC

Input

Filter

DRAIN

VCC

GND_IC

DRAIN

D1

D2

Output Power [W]

Switching Frequency

[kHz]

25

65

mode 1

mode 2

mode 3

mode 4

Switching

OFF

[V]