SC283 SEMTECH [Semtech Corporation], SC283 Datasheet - Page 13

• Manufacturer Part Number: SC283
• Description: Dual Channel 2.5MHz, 1.8A Synchronous Step-Down Regulator
• Manufacturer: SEMTECH [Semtech Corporation]

Applications Information (continued)
and 3b show the maximum allowable load current based
upon the limit of maximum loss for V
respectively. The curves are drawn for high duty-cycle
operation. If the operating duty-cycle is lower, the loss is
lower allowing higher load current.
Protection Features
The SC283 provides the following protection features:
Current Limit and Protection
The internal PMOS power device in the switching stage
is protected by a current limit feature. If the inductor
current is above the PMOS current limit for 16 consecutive
cycles, the part enters foldback current limit mode and
the output current is limited to the current limit holding
current (I
this condition, the output voltage will be the product
of I
holding current will decrease when the output voltage
increases. The load presented must fall below the current
limit holding current for the part to exit foldback current
limit mode. Figure 4 shows how the typical current limit
holding current varies with output voltage. The SC283 is
capable of sustaining an indefinite short circuit without
damage and will resume normal operation when the fault
is removed. The foldback current limit mode is disabled
during soft-start. Current limit functionality is shown in
Figure 6.
© 2010 Semtech Corp.
Figure 2 — Maximum allowable loss for each channel
•
•
•
•
CL_HOLD
for a maximum junction temperature of 125°C
Current Limit
Over-Voltage Protection
Soft-Start Operation
Thermal Shutdown
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
CL_HOLD
and the load resistance. The current limit
T
A
= 85° C
) of a few hundred milliampere. Under
T
A
= 55° C
SC283 Maximum Loss for T
Loss of Channel A (W)
T
A
= 25° C
IN
J
=125° C
=3.3V and V
IN
=5.0V,
13
channel for a maximum junction temperature of 125°C
Figure 3 — Maximum allowable Load Current for each
Figure 4 — Typical Current Limit Holding Current
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
300
250
200
150
100
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
50
0
1.0
V
V
V
V
IN
OUT
IN
OUT
= 5.0V
= 3.3V
SC283 Maximum Load Current for T
= 3.3V
SC283 Maximum Load Current for T
= 2.5V
Current Limit Holding Current over Vout
(b) V
(a) V
1.5
V
IN
IN
Load Current of Channel A (A)
IN
Load Current of Channel A (A)
= 3.3V
= 3.3V, V
= 5.0V, V
T
T
A
Output Voltage (V)
T
A
= 85° C
2.0
= 85° C
A
V
= 70° C
IN
= 3.6V
OUT
OUT
=2.5V
=3.3V
2.5
T
A
= 60° C
V
www.semtech.com
IN
J
J
=125° C
=125° C
= 5.0V
T
3.0
A
T
= 25° C
T
A
A
SC283
 47° C
 42° C
3.5