AN937 Datasheet, PDF (22/29 Pages) STMicroelectronics – The L4971 is a 1.5 A monolithic dc-dc converter

Typical application
AN937
3.6
Compensation network
The complete control loop block diagram is shown in Figure 29. The error amplifier basic
characteristics are:
gm = 2.5mS
Ro = 1.2MΩ
Avo = 60dB
Isource/sink = 300 μA
Figure 27. Output drop (%) vs minimum input voltage
3.5
3
2.5
2
1.5
1
0.5
0
10
15
20
25
30
35
40
45
Vin
Cout = 1 x 150uF
Cout = 2 x 150uF
Cout = 3 x 150uF
Figure 28. Block diagram compensation loop
V_REF
A(s)
Vc/Vct
LC
V_O
+-
α
D97IN697
Cc
gm
Ro
Co
Rc
A_vo=g_m·R_o
D97IN698
L
Cout
Resr
D97IN700
22/29
Doc ID 5655 Rev 15