L4990 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L4990' PDF : 24 Pages View PDF
Figure 40. Protection against overvol-
tage/feedback disconnection (not
latched)
RSTART
VREF
VCC
4
8
DC
L4990
3
12
11
D97IN511A
L4990 - L4990A
Figure 41. Device shutdown on overcurrent
L4990
VREF
4
R1
DIS
14
Ipk max ≅
2.5
RSENSE
• 1- R2
R1
I
Ipk
R2
13
11
12
PGND SGND
ISEN
OPTIONAL
RSENSE
D97IN512A
Figure 42. Constant power in pulse-by-pulse current limitation (flyback discontinuous)
VIN
80 ÷ 400VDC
OUT
10
L4990
13
11
12
PGND SGND
ISEN
RFF
R
Lp
RFF = 5·106
R·Lp
RSENSE
RSENSE
Figure 43. Voltage mode operation.
D97IN513
DC
3
10K
L4990
6
COMP
12
SGND
13
ISEN
D97IN570A
REFERENCES
[1] Efficient active Clamp for Off-line Applications using L4990 and L6380 (N.Tricomi, G. Gattavari,
C. Adragna, PCIM96 - NURBERG).
[2] 25W Off-Line Autoranging Battery Charger with L4990 (AN889)
[3] 300W Secondary Controlled Two-Switch Forward Converter with L4990 (AN890)
[4] SMPS with L4990 for Multisync Monitors (AN891)
[5] High performance VRM using L4990A, for Pentium Pro® processor (AN908).
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