LV5028TT

No.A1999-13/16

3. OVP (Over voltage protection)

If the voltage of VIN pin is higher than the internal reference voltage VINOVP (27V typ), switching operation is

stopped.

The stopping operation is kept until the voltage of VIN is lower than 7.3V. If the voltage of VIN pin is higher than 9V,

the switching operation is restated.

4. TSD (Thermal shut down protection)

The thermal shutdown function works when the junction temperature of IC is 165

°C (typ) ( A ), and the IC switching

stops. The IC starts switching operation again when the junction temperature is 135

°C typ ( B ) or lower.

Skip frequency function

LV5028TT contains the skip frequency function for reduction of the peak value of conduction noise. This function

changes the frequency as follows.

Switching frequency is changed as follows.

…×0.9 → ×1.1 →

×1.05 →

×1 →

×0.95 →

×0.9 →

×1.1 …

(45kHz)

(55kHz)

(52.5kHz)

(50kHz)

(47.5kHz)

(45kHz)

(55kHz)

It’s repeated by this loop.

VIN

voltage

Operation start

OVP reset

OVP

Time

Time

9V typ

7.3V typ

27V typ

on

C

A

B

on

off

Outputstage

Time

Time

TSD (design target)

165

°C

135

°C

A

B

on

on

off

Outputstage

Tj

(Junction tmperature)

UVLO unlocked

VIN

OUT

45k

45k

50k

55k

52.5k

47.5k

Skip frequency function