ISL6740 INTERSIL [Intersil Corporation], ISL6740 Datasheet - Page 25

• Manufacturer Part Number: ISL6740
• Description: Flexible Double Ended Voltage and Current Mode PWM Controllers
• Manufacturer: INTERSIL [Intersil Corporation]

The gain and phase plots combined with the opto coupler’s
transfer characteristics appear in Figures 24A and 24B:
-135
-180
-45
-90
-10
30
20
10
FIGURE 24A. EA PLUS OPTO COUPLER GAIN
90
45
FIGURE 24B. EA PLUS OPTO COUPLER GAIN
0
0
10
10
100
100
FREQUENCY (Hz)
1•10
1•10
FREQUENCY (Hz)
25
3
3
1•10
1•10
4
4
1•10
1•10
5
5
ISL6740, 1SL6741
1•10
1•10
6
6
Using the control-to-output transfer function combined with
the EA transfer function, the loop gain and phase may be
predicted. The predicted loop gain and phase margin of the
converter appear in Figures 25A and 25B:
-135
225
180
135
FIGURE 25B. PREDICTED LOOP PHASE MARGIN
-45
-90
-10
-20
-30
-40
-50
90
45
50
40
30
20
10
0
0
100
100
FIGURE 25A. PREDICTED LOOP GAIN
1•10
1•10
FREQUENCY (Hz)
FREQUENCY (Hz)
3
3
1•10
1•10
4
4
July 13, 2007
1•10
FN9111.4
1•10
5
5