Current Mode PWM Controller
4.7 k
1k
ERROR AMP
ADJUST
4.7k
2N 2222
100 k
5k
ISENSE
ADJUST
RT
SG1842/43
1 COMP
VREF 8
2 VFB
VCC 7
3 ISENSE
OUTPUT 6
4 RTCT
GROUND 5
A
0.1µF 0.1µF 1k
CT
VREF
VCC
OUTPUT
GROUND
Figure 26 · Open Loop Laboratory Fixture
High-peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and
bypass capacitors should be connected to pin 5 in a single point ground.
The transistor and 5kΩ potentiometer are used to sample the oscillator waveform and apply an adjustable
ramp to pin 3.
18