Fairchild RC5050, RC5051 Evaluation Summary, Case Temperature, Iload = 13.9A, Device Description

AN50 APPLICATION NOTE

Input Ripple and Power on Input Rush Current

Iload = 9.9A	Input Ripple	Refer to Attach-
	Voltage = 15mV	ment G for Scope
		Picture

Note:

Excellent input ripple voltage. Input ripple voltage is recom- mended to be less than 5% of the output voltage.

Component Case Temperature

Power on Input Rush Current was not measured on the moth- erboard because we did not want to cut the 5V trace and insert a current probe in series with the supply. However, with the input filter design, the Input Rush Current is well within specification.

		Case Temperature	Case Temperature	Case Temperature
		Iload = 9.9A	Iload = 12.4A	Iload = 13.9A
Device	Description	(°C)	(°C)	(°C)
Q3A	MOSFET	57	63	66.3
	K1388
Q3B	MOSFET	58	64	66.6
	K1388
L1	Inductor,	53	56	61.2
	Unknown
Q2	Schottky Diode	66	70	87
	2048CT
IC	Raytheon’s RC5050	52	54	58
Cin	Input Cap. 1000∝F	38.2	36.8	39
Cout	Output Cap.	35	34.8	38.2
	1500∝F

Note:

The values for case temperatures are within guidelines. That is, case temperatures for all components should be below 105°C @25°C Ambient.

Evaluation Summary

The on-board DC-DC converter is fully functional. It has excellent load regulation, transient response, and input volt- age ripple.

Attachment A Attachment B

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