sc183c Semtech Corporation, sc183c Datasheet - Page 14

• Manufacturer Part Number: sc183c
• Description: 2.5mhz, 2a Synchronous Step-down Regulator
• Manufacturer: Semtech Corporation

© 2009 Semtech Corp.
Applications Information (continued)
Stage
0
Stage
6
A
J
F
Stage
SC4633 Soft Start
M
1
Stage
Stage
I
Stage
5
6
SC4633 Over Current Protection
7
G
B
Stage
9
K
Stage
Figure 3 — Typical Diagram of Current Limit Protection
H
2
E
Figure 2 — Typical Diagram of Soft Start Operation
Stage
8
L
Stage
Stage
C
3
4
D
Conditions
Conditions
Stages
Stages
G
A
B
C
D
E
F
H
K
M
0
1
2
3
4
5
6
6
7
8
9
J
L
I
4
Chip is OFF.
Peak current limit at 20% level
PWM "ON" when inductor current of 0A
PWM "OFF" when inductor current hits peak current limit
Stage duration of 200us
Peak current limit at 25% level
PWM "ON" when inductor current of 0A
PWM "OFF" when inductor current hits peak current limit
Stage duration of 200us
Peak current limit at 40% level
PWM "ON" when inductor current of 500mA
PWM "OFF" when inductor current hits peak current limit
Stage duration of 200us
Peak current limit at 100% level
PWM "ON" when inductor current of 500mA
PWM "OFF" when inductor current hits peak current limit
Stage duration of 200us
Peak current limit at 100% level
Switch to close-loop PWM operation.
Soft Start ends.
Normal PWM operation
Overload protection is enabled
AVIN=PVIN > UVLO Threshold
.and. One or more CTL pin is high.
.and. Internal reference is ready.
End of stage 1 .and. Vout<86% target
End of stage 2 .and. Vout<86% target
End of stage 3 .and. Vout<86% target
End of stage 4 .and. Vout<86% target
Vout>86% target
Vout>86% target
Vout>86% target
End of soft start time of 800us
Soft Start ends.
Normal PWM operation
Overload protection is enabled
Cycle by cycle peak current limit
OCP protection is actived
foldback peak current limit to around 600mA
PWM "ON" when inductor current of 0A
PWM "OFF" when inductor current hits peak current limit of 600mA
Normal PWM operation
Switch peak current limit to 100% level
Inductor current hits peak current limit
Peak current limit for 16 consecutive cycles
Vout  100% target
Inductor current doesn't hit peak current limit
Operation description
Operation description
Operation description
Operation description
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SC183C