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August 08, 2012 |DATA SHEET | 3.4

13

IR3899 

9A Highly Integrated SupIRBuck

Single‐Input Voltage, Synchronous Buck Regulator  

PD‐97661

THERMAL DERATING CURVES 

Measurement done on Evaluation board of IRDC3899.PCB is 4 layer board with 2 oz Copper, FR4 material, size 2.23"x2" 

 

PVin = 12V, Vout=1.2V, Vcc = Internal LDO (6.4V), Fs = 600kHz 

8

8.5

9

9.5

10

10.5

25

30

35

40

45

50

55

60

65

70

75

80

85

Tamb(ºC)

0 LFM

200 LFM

Lout-0.51uH,0.29mΩ(Vitec 59PR9876N)

 

PVin = 12V, Vout=3.3V, Vcc = Internal LDO (6.4V), Fs = 600kHz 

6

6.5

7

7.5

8

8.5

9

9.5

10

10.5

25

30

35

40

45

50

55

60

65

70

75

80

85

Tamb(ºC)

0 LFM

200 LFM

Lout-1.2uH,2.9mΩ(Delta MPL105-1R2)

 

Note: International Rectifier Corporation specifies current rating of SupIRBuck devices conservatively. The continuous current

load capability might be higher than the rating of the device if input voltage is 12V typical and switching frequency is below 750

kHz.The above derating curves are generated at 12V input ,600kHz with 0-200LFM air flow and ambient temperature up to

85°C.Detailed thermal derating information can be found in the Application Note AN-1174 “Thermal Derating of DC-DC

Convertors using IR3899/98/97”. However, the maximum current is limited by the internal current limit and designers need to

consider enough guard bands between load current and minimum current limit to guarantee that the device does not trip at

steady state condition.