boost inverter: why external tip33 and Rsense resistor get heated?

[hassanmd]

i am using TL497A for inverting Power supply from 12 to -18. all the circuit is like on datasheet. but the Sense resisitor and Transistor get heated at load and power down the voltage to -15 volt. without load nothing is heated and voltages are full.

i think the base current ,determined by the resistor network from Vcc may cause it. but ihave tested with diferent Ib. but no use. Or PCB lay out can be the problem?? can any one help.
i have attached the datasheet.

 

[Prototyp_V1.0]

Heat will depend of value of Rcl and how much load you have on output. I'll guess you have either of these or a combination.

 

[hassanmd]

Heat will depend of value of Rcl and how much load you have on output. I'll guess you have either of these or a combination.

do u Rcl means? Rsense? and load current is only 90 mili amps. crcuit is exactly like datasheet for inverter 12 to -18v with external transsitor. today i remove the Rsense and the circuit works much better. but didnt understand. before tihis transsitor or Rsense get heated and suddenly powerdowned.