8

7

6

1

2

R*

8

7

6

1

2

a) EXTERNAL npn SWITCH

b) EXTERNAL pnp SATURATED SWITCH (see Note A)

MC33063A

MC34063A

www.ti.com

SLLS636L – DECEMBER 2004 – REVISED DECEMBER 2009

A.

If the output switch is driven into hard saturation (non-Darlington configuration) at low switch currents (

≤300 mA) and

high driver currents (

≥30 mA), it may take up to 2 μs to come out of saturation. This condition will shorten the off time

at frequencies

≥30 kHz and is magnified at high temperatures. This condition does not occur with a Darlington

configuration because the output switch cannot saturate. If a non-Darlington configuration is used, the output drive

configuration in Figure 7b is recommended.

Copyright © 2004–2009, Texas Instruments Incorporated

Submit Documentation Feedback

7

Product Folder Link(s): MC33063A MC34063A