S3843
6. Open Loop Test
V
REF
2N2222
4.7K
100K
1 COMP
ERROR
1K
AMP
ADJUST
4.7K
I
SENSE
ADJUST
2 V in
3 I
SENSE
4 R
T
/C
T
V
REF
5
V cc 6
OUTPUT 7
8
0.1uF
0.1uF
1K/1W
OUTPUT
R
T
V cc
High peak currents associated with capacitive leads necessitate careful grounding techniques. Timing and bypass
capacitors should be connected close to Pin5 in a single point ground. The transistor and 5
㏀
potentiometer are
used to sample the oscillator waveform and apply an adjustable ramp to Pin3.
S3843
GND
GROUND
7. Slope Compensation
V
0.1u F
RE F
A fraction of the oscillator ramp can be resistively
R
T
8
summed with the current sense signal to provide
slope compensation for converters requiring duty
cycle over 50%. Note that capacitor C, forms a
R
1
R
2
I
SEN SE
R
T
/C
T
4
C
T
filter with R
2
to suppress the leading edge switch
spikes.
I
SEN SE
3
C
R
SEN SE
KSI-8007-001
6
AUK [ AUK CORP ]
