Page 197 - Troubleshooting Analog Circuits

184 14. Real Circuits and Real Problems

'MOUNTED ON STAVER HEATSINK No. V5-1.
Q1= BD344
Q2 = 2N5023
L1- AOTURNS NO. 22 WIRE ON FERROXCUBE No. K300502 TOROID CORE.
Figure 14.9. LM3524 Switching Regulator.

Table 14.9 Troubleshooting LM3524 Switching Regulators, SIMPLIFIED
Indication of Trouble Possible Cause Solution
Something overheats. Frequency too high? Measure F at pin 7.
Bad D1 rectifier? Check D 1.
Bad transistors? Check transistors.
Bad capacitor? Check capacitor.
Bad LM3524? Check LM3524.
Clock frequency bad. Bad capacitor? Check Ct at pin 7.
Bad resistor? Check Rt at pin 6.
Bad loop stability. Bad R-C damper? Check R-C at pin 9.
Bad C6? Swap a good cap.
Bad inductor? Check L1.
Bad current limit. Bad R,,,? Check R,,,, at pins 4.5.
Output voltage tolerance Bad resistors? Check R1,2,4,5.
is bad. Bad reference? Check V at pins 16.2, 1.
Transistor overheats. Resistors bad? Check R8.9, 10.
Bad inductor? Check L1.
Nothing works. Solder shorts? Look for solder shorts.
Something bad. Check everything.
Can't drive rated load. Bad transistor? Check Q1, Q2. Swap in
good transistors.
Bad input voltage? Check Vi,, with scope.
Bad 3524? Study all data, swap in
a known good part.
etc.. etc.. etc.. etc.. etc.. etc. . .