SSC2102S datasheet(13/21 Pages) SANKEN

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SSC2102S

SSC2102S-DS Rev.1.2

SANKEN ELECTRIC CO.,LTD.

Dec. 08, 2014

2) When both VOUT1 and VOUT2 are High, the output

which is set to High ahead is set to Low as shown

in Figure 8-15。.

IS pin voltage

OUT2 pin

voltage, VOUT2

OUT1 pin

voltage, VOUT1

VIS(OCPL)

Figure 8-15 OCP operation by VIS(OCPL)

(Both VOUT1 and VOUT2 are High)

 IS Pin Overcurrent Protection Threshold Voltage

(High)：VIS(OCPH)

This protection operates on such abnormal conditions

as the inductor is shorted or is saturated. When the

inductor current of L1 and L2 increases abnormally

and IS terminal voltage decreases to VIS(OCPH) = − 0.55

V or less, the control circuit sets both VOUT1 and

VOUT2 to Low on pulse-by-pulse basis as shown in

Figure 8-16.

IS pin voltage

OUT2 pin voltage,

VOUT2

OUT1 pin voltage,

VOUT1

VIS(OCPH)

Figure 8-16 OCP operation by VIS(OCPH)

8.7 Overvoltage Protection (OVP)

Figure 8-17 shows VFB pin peripheral circuit and

Figure 8-18 shows the operational waveforms of

Overvoltage Protection (OVP).

The output overvoltage is detected by using VFB pin.

There are two threshold voltages, VFB(SOVP) for Soft

Overvoltage Protection (SOVP) and VFB(OVP) for OVP.

The operations are shown below.

ROUT2

VOUT

RCS

LINE

GND

ROUT1

GND

VFB

COMP

CFB

ICOMP(SI)

Figure 8-17 VFB pin peripheral circuit

VFB pin voltage

OUT1 pin voltage,

VOUT1

COMP pin current

ICOMP(SK)

VFB(SOVP)

VFB(OVP)

VFB(REF)

OUT2 pin voltage,

VOUT2

Figure 8-18 Operational waveform of OVP

 Soft Overvoltage Protection (SOVP)

When VFB pin voltage increases to VFB(SOVP) = 3.68

V, Soft Overvoltage Protection (SOVP) is activated.

Thus, COMP pin is discharged by ICOMP(SI) = 100 μA

and the output voltage is decreased.

VFB(SOVP) is equivalent to about 105% of the rated

output voltage. The output voltage, which operates

SOVP, is calculated approximately as follows.

)

SOVP

(

FB(REF)

OUT

)

SOVP

(

OUT





(V)

(8-3)

where,

VOUT

：Output voltage in normal operatioin

VFB(REF) ：Error AMP reference voltage, 3.5 V

 Overvoltage Protection (OVP)

When VFB pin voltage increases to VFB(OVP) = 3.72 V,

Overvoltage Protection (OVP) is activated. And thus

both OUT1 and OUT2 are set to Low. When VFB pin

voltage decreases to VFB(SOVP), the control circuit

deactivate both OVP and SOVP, and reverts to

switching operation. VFB(OVP) is equivalent to about

106 % of the rated output voltage. The output voltage,

which operates OVP, is calculated approximately as

follows.

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